**Impact of Shrimp Farming on Mangrove Forest and Other Coastal Wetlands: The Case of Mexico**

César Alejandro Berlanga-Robles1, Arturo Ruiz-Luna1 and Rafael Hernández-Guzmán2 *1Centro de Investigación en Alimentación y Desarrollo A. C.,* 

*Unidad Regional Mazatlán 2Posgrado en Ciencias del Mar y Limnología, UNAM Mexico* 

#### **1. Introduction**

16 Aquaculture and the Environment - A Shared Destiny

Zárate Ovando, M. B. (2007). Ecología y conservación de las aves acuáticas del complejo

G., Serviere-Zaragoza E., Riosmena-Rodriguez R., I Sánchez-

Paz, Mexico.

Master of Science Thesis. Cibnor S.C. La Paz. México. 110 pp. Hernández-Carmona

lagunar Bahía Magdalena-Almejas, B. C. S., México. Ph.D Thesis. CIBNOR, S. C., La

Since the middle of the twentieth century, the shrimp farming industry has shown steady growth along the tropical and subtropical coasts of the world. The world's cultivated shrimp production in 1950 was 1325 tons, amounting just 0.3% of the total production for these crustaceans, which were mainly extracted from coastal and estuarine environments. Thirty years later, by 1982, the global shrimp production surpassed one million tons. By 2009, shrimp production grew to nearly 3.5 million tons valued at approximately 14.6 billion dollars, amounting to 34% of the world's shrimp production, including marine and estuarine catches (Fig. 1) (FAO, 2011).

This escalation has seen intense debate regarding the economic, social and, particularly, environmental impacts produced by this activity. There is special concern for wetland losses, increased organic loading in coastal waters, the introduction of exotic species and the dispersal of harmful diseases (Boyd and Clay, 1998; Primavera, 2006).

The most controversial impact of shrimp farming is related to habitat loss. One of the main concerns is the deforestation of mangrove, a coastal vegetation type recognized as a highly productive shelter habitat for many commercial aquatic species. It has been estimated that between 1.0 and 1.5 million hectares of the world's coasts are covered by some type of shrimp farming (extensive, semi-intensive or intensive systems), and between 20 and 40% of this area is blamed as a cause of mangrove loss (Primavera, 2006). Thailand is considered to be an extreme example of this problem, as mangrove cover in this country was halved from 1960 to 1996. Approximately 200,000 ha of mangroves were deforested, with a third of the area being transformed into shrimp farming ponds (Aksornkoae & Tokrisna, 2004).

Although shrimp farming impacts have been widely documented and discussed, there is little evidence on the real mangrove deforestation rates at regional or national scales due to this activity. Thus, some of the global estimates on mangrove deforestation for shrimp pond construction are imprecise projections based on very local studies or generalizations of extreme cases such as Thailand.

Impact of Shrimp Farming on Mangrove Forest and Other Coastal Wetlands: The Case of Mexico 19

per kg, with feed and seed prices as the major constraints for investors (Ponce-Palafox et al., 2011). However, farmed shrimp production has grown from 0.05% to 40% of the total national production for this crustacean (FAO, 2011), and Mexico is currently positioned among the ten largest producers of farmed shrimp in the world (Fig. 1) (Conapesca, 2009;

At the country level, shrimp aquaculture is practiced in almost all 17 coastal states. Even in inland locations, there are some initiatives to cultivate the same species used in marine aquaculture but adapted to freshwater environments. Although shrimp aquaculture is widespread nationally, the Gulf of California region is the most highly concentrated region of activity, with the states of Sonora, Sinaloa and Nayarit representing more than 95% of the total shrimp pond extent and production in Mexico. By contrast, Jalisco, Michoacán, Oaxaca, Chiapas and Tabasco together amount to less than 1% (Fig. 2) because physiographic or

Some species of the genera *Litopenaeus* and *Farfantepenaeus* have been used for commercial purposes, but the white shrimp *L. vannamei* is currently the most common species in culture. This species is grown in one (8-9 months) or two cycles (3-4 months each) a year, obtaining a final weight between 10 to 25 g in the first case and 7 to 11 g in the second. Even when the use of wild postlarvae (PL) is allowed in Mexico, with permission granted for extraction, this activity is sustained by PL production controlled in 33 laboratories that produce in average of approximately 76 million PL per year. The last reliable record of aquaculture in Mexico (CONAPESCA, 2010) states a total output of approximately 72 900 ha as of 2008 (Figure 1). In almost all cases, the shrimp farms use semi-intensive production systems, which, aside from the certified larvae, require substantial amounts of fertilizers to increase natural productivity and complementary feed to maintain stocking densities from 6 to 30

With this system, and considering the figures on total shrimp pond area and production, the average yield from 2000 to 2008 was 1260 kg ha-1 (Fig. 1), although it was lower from 2000 to 2003, when sanitary problems associated with viral diseases occurred, increasing later to approximately 1750 kg ha-1, a level that has been maintained since 2006 (CONAPESCA, 2009; 2010). In agreement with Ponce-Palafox et al. (2011), the top three producer states in Mexico obtained average yields of 800 (Nayarit), 900 (Sinaloa) and 3200 (Sonora) kg ha-1 per crop.

**2. Methods: Land use changes associated with shrimp farming in Mexico** 

and Sonora in the Gulf of California and Tamaulipas in the Gulf of Mexico (Figure 2).

To analyze the land use changes caused by shrimp farming in Mexico and to estimate rates of coastal wetland loss induced by this activity, we performed a change detection analysis in three steps following a procedure similar to that proposed by Berlanga-Robles et al. (2011). Because shrimp farming in Mexico is concentrated around the northern states, particularly the east coast of the Gulf of California, to make this study representative, four states that account for 97% of this activity in extent and production were chosen for the analysis: Nayarit, Sinaloa

First, the shrimp farms of the four states selected were geographically located with a database provided by the National Commission for Fisheries and Aquaculture (CONAPESCA).

economic factors have inhibited the development of this activity.

2010).

postlarvae per area (PL/m2).

**2.1 Shrimp farm location and inventory** 

Fig. 1. Shrimp farming indicators: A) World shrimp production (1984-2009). B) Main producing countries (2005-2009). C) Mexican shrimp farming production (1984-2009). D) Extent and annual yield in Mexico (2000-2008).

The objective of the present study was analyze the land use changes caused by shrimp farming in the coastal landscape of Mexico, one of the main producers worldwide, using remote sensing (RS) and geographic information system (GIS) tools within a landscape change framework to contribute to a better understanding of the impacts of shrimp farming on coastal wetlands. The results were then compared with others obtained at different latitudes to gain a more precise knowledge of the responsibility of shrimp farming on mangrove deforestation and other environmental impacts.

#### **1.1 Shrimp farming in Mexico**

Shrimp farming has its origin in the late nineteenth century, but it was not until the 1960s and early 1970s that it became a commercial activity (Kungvankij et al., 1986). Mexico followed a similar trend, starting shrimp production in the early 1970s with the operation of an experimental farm to the northwest. However, legal issues related to land tenure complicated this development, particularly for private investments, until the middle 1980s, when laws changed, allowing the expansion of commercial farms, mainly in the same region.

Thereafter, like the rest of the world, shrimp farming in Mexico displayed rapid evolution, growing from 35 t of shrimp production in 1985 to 125,778 t in 2009 (Fig. 1). Profits also increased, from \$ 175,000 to 405 million dollars, respectively. The net income by farms in northwest Mexico (semi-intensive systems) has been estimated between US\$1.2 and US\$2.9

Fig. 1. Shrimp farming indicators: A) World shrimp production (1984-2009). B) Main producing countries (2005-2009). C) Mexican shrimp farming production (1984-2009). D)

The objective of the present study was analyze the land use changes caused by shrimp farming in the coastal landscape of Mexico, one of the main producers worldwide, using remote sensing (RS) and geographic information system (GIS) tools within a landscape change framework to contribute to a better understanding of the impacts of shrimp farming on coastal wetlands. The results were then compared with others obtained at different latitudes to gain a more precise knowledge of the responsibility of shrimp farming on

Shrimp farming has its origin in the late nineteenth century, but it was not until the 1960s and early 1970s that it became a commercial activity (Kungvankij et al., 1986). Mexico followed a similar trend, starting shrimp production in the early 1970s with the operation of an experimental farm to the northwest. However, legal issues related to land tenure complicated this development, particularly for private investments, until the middle 1980s, when laws changed, allowing the expansion of commercial farms, mainly in the same

Thereafter, like the rest of the world, shrimp farming in Mexico displayed rapid evolution, growing from 35 t of shrimp production in 1985 to 125,778 t in 2009 (Fig. 1). Profits also increased, from \$ 175,000 to 405 million dollars, respectively. The net income by farms in northwest Mexico (semi-intensive systems) has been estimated between US\$1.2 and US\$2.9

Extent and annual yield in Mexico (2000-2008).

**1.1 Shrimp farming in Mexico** 

region.

mangrove deforestation and other environmental impacts.

per kg, with feed and seed prices as the major constraints for investors (Ponce-Palafox et al., 2011). However, farmed shrimp production has grown from 0.05% to 40% of the total national production for this crustacean (FAO, 2011), and Mexico is currently positioned among the ten largest producers of farmed shrimp in the world (Fig. 1) (Conapesca, 2009; 2010).

At the country level, shrimp aquaculture is practiced in almost all 17 coastal states. Even in inland locations, there are some initiatives to cultivate the same species used in marine aquaculture but adapted to freshwater environments. Although shrimp aquaculture is widespread nationally, the Gulf of California region is the most highly concentrated region of activity, with the states of Sonora, Sinaloa and Nayarit representing more than 95% of the total shrimp pond extent and production in Mexico. By contrast, Jalisco, Michoacán, Oaxaca, Chiapas and Tabasco together amount to less than 1% (Fig. 2) because physiographic or economic factors have inhibited the development of this activity.

Some species of the genera *Litopenaeus* and *Farfantepenaeus* have been used for commercial purposes, but the white shrimp *L. vannamei* is currently the most common species in culture. This species is grown in one (8-9 months) or two cycles (3-4 months each) a year, obtaining a final weight between 10 to 25 g in the first case and 7 to 11 g in the second. Even when the use of wild postlarvae (PL) is allowed in Mexico, with permission granted for extraction, this activity is sustained by PL production controlled in 33 laboratories that produce in average of approximately 76 million PL per year. The last reliable record of aquaculture in Mexico (CONAPESCA, 2010) states a total output of approximately 72 900 ha as of 2008 (Figure 1). In almost all cases, the shrimp farms use semi-intensive production systems, which, aside from the certified larvae, require substantial amounts of fertilizers to increase natural productivity and complementary feed to maintain stocking densities from 6 to 30 postlarvae per area (PL/m2).

With this system, and considering the figures on total shrimp pond area and production, the average yield from 2000 to 2008 was 1260 kg ha-1 (Fig. 1), although it was lower from 2000 to 2003, when sanitary problems associated with viral diseases occurred, increasing later to approximately 1750 kg ha-1, a level that has been maintained since 2006 (CONAPESCA, 2009; 2010). In agreement with Ponce-Palafox et al. (2011), the top three producer states in Mexico obtained average yields of 800 (Nayarit), 900 (Sinaloa) and 3200 (Sonora) kg ha-1 per crop.

#### **2. Methods: Land use changes associated with shrimp farming in Mexico**

To analyze the land use changes caused by shrimp farming in Mexico and to estimate rates of coastal wetland loss induced by this activity, we performed a change detection analysis in three steps following a procedure similar to that proposed by Berlanga-Robles et al. (2011). Because shrimp farming in Mexico is concentrated around the northern states, particularly the east coast of the Gulf of California, to make this study representative, four states that account for 97% of this activity in extent and production were chosen for the analysis: Nayarit, Sinaloa and Sonora in the Gulf of California and Tamaulipas in the Gulf of Mexico (Figure 2).

#### **2.1 Shrimp farm location and inventory**

First, the shrimp farms of the four states selected were geographically located with a database provided by the National Commission for Fisheries and Aquaculture (CONAPESCA).

Impact of Shrimp Farming on Mangrove Forest and Other Coastal Wetlands: The Case of Mexico 21

Fig. 3. Technical process to detect and assess landscape changes produced by shrimp ponds

construction based on satellite imagery analysis and ancillary data.

Fig. 2. Shrimp farming in Mexico. The bar graph shows the proportion of pond area by state and the bar graph shows production by state from 2004 to 2008.

This database was updated and corrected by visual interpretation of the Quickbird and GeoEye imagery available on Google Earth (2002 to 2011) as well as false-color composites from Landsat TM (2010 and 2011) and SPOT panchromatic (2010) imagery with a 30 and 2.5 m pixel size (Figure 3).

When the polygons in the four states were completed, a 500 m buffer zone was created around them using geographic information system (GIS) tools. The farms' area and their buffer zones were then used to mask the Landsat TM images used in the next step so that the area outside of them formed a background without spectral information.

Fig. 2. Shrimp farming in Mexico. The bar graph shows the proportion of pond area by state

This database was updated and corrected by visual interpretation of the Quickbird and GeoEye imagery available on Google Earth (2002 to 2011) as well as false-color composites from Landsat TM (2010 and 2011) and SPOT panchromatic (2010) imagery with a 30 and 2.5

When the polygons in the four states were completed, a 500 m buffer zone was created around them using geographic information system (GIS) tools. The farms' area and their buffer zones were then used to mask the Landsat TM images used in the next step so that

the area outside of them formed a background without spectral information.

and the bar graph shows production by state from 2004 to 2008.

m pixel size (Figure 3).

Fig. 3. Technical process to detect and assess landscape changes produced by shrimp ponds construction based on satellite imagery analysis and ancillary data.

Impact of Shrimp Farming on Mangrove Forest and Other Coastal Wetlands: The Case of Mexico 23

Subsidiary cover Nayarit Sinaloa Sonora Tamaulipas TOTAL Aquatic surfaces 103 (2) 1918 (5) 268 (1) 24 (1) 2313 (3) Mangrove 392 (8) 689 (2) 85 (<1) 0 1166 (1) Saltmarsh 1726 (35) 23225 (56) 10779 (33) 48 (6) 35778 (45) Terrestrial covers 2507 (50) 12215 (30) 21133 (64) 929 (93) 36784 (46) Shrimp farming\* 238 (2) 3090 (2) 642 (2) 0 3970 (5)

extent (ha) 4966 41137 32907 1001 80011

projects. It is important to highlight that shrimp aquaculture started prior to 1986, the date of the first Landsat image included in this analysis, which explains why 5% of the shrimp aquaculture use was unchaged in land use . It means that approximately 4000 ha of shrimp

As most of the changes happened in the Gulf of California region, it is important to have look at Tamaulipas, the only representative of shrimp aquaculture in the Gulf of Mexico. No mangrove deforestation was associated with shrimp ponds, and the main subsidiary cover was terrestrial cover, amounting to 93% of the total area used for shrimp pond installation. Based on the 1973 estimates for mangrove distribution proposed by Ruiz-Luna et al. (2010) for the Gulf of California region, the change detection analysis output some differences with the previous analysis, showing a slight reduction of the assessed mangrove loss for Nayarit and Sonora (Table 2). The mangrove change at Nayarit was 77 ha less, as evaluated with the 1973 map with respect to the 1986 map. The changes in Sonora were similar in both studies; even so, the reduction is 14 ha more with the 1986 map than that estimated with the 1973 map. The differences in both cases are approximately 15-20%. By contrast, the mangrove loss estimated for Sinaloa increased by approximately 40% when the 1973 map was analyzed, agreeing with a technical report published by Ruiz-Luna et al. (2005). Even so, the technical differences in both Landsat devices (MSS and TM) make an underestimation of the 1973 mangrove area possible due the low resolution of the Landsat MSS imagery (60 m) used to produce these maps, as noted by Ruiz-Luna et al. (2010). Thus, the differences among Nayarit and Sonora could be reduced, but in the case of Sinaloa, it could increase.

> Land covers (1973) State Mangrove Others covers Total

Nayarit 315 (6) 4651 (94) 4966 Sinaloa 956 (2) 40181 (98) 41376 Sonora 71 (<1) 32836 (>99) 32907

Table 2. Change detection matrix for land cover change from mangrove (1973) to shrimp

farms (2010). Area in hectares and relative proportion (%) in parenthesis.

ponds had been constructed by 1986 on undetermined covers.

Table 1. Land use changes produced by shrimp farming in four states of Mexico. Area in hectares and corresponding proportion (%) in parenthesis. \*Some farms were built before 1986, the initial time for this study (t1), consequently, figures in this row represent no

State

Total shrimp farm

change after this date.

Shrimp farms (2010)

#### **2.2 Landscape characterization**

In the second step, performed by analysts different than those whose updated and prepared the shrimp farm polygons, the coastal landscape of four selected states before the advent of shrimp farming were characterized by means of thematic maps generated by the classification of Landsat TM images from 1986 to 1999, downloaded from the USGS Global Visualization Viewer portal (http://glovis.usgs.gov/). The imagery covering the shrimp farming area in the states of the Gulf of California comprises 14 Landsat TM images among paths 30 to 37 and rows 39 to 45. The area of Tamaulipas was covered with three images recorded in path 26 among rows 41 and 43. All the spectral bands except thermal infrared were used.

The images underwent unsupervised classification using a K-means clustering technique (Richards & Jia, 1999). A 16 spectral cluster map was produced first, which was subsequently associated with natural covers represented by three coastal wetland types (aquatic surfaces, saltmarsh and mangroves), while other natural vegetation (dry forest, thorn scrub forest) and vegetation of anthropic origin (agriculture, settlements, lineal infrastructure) were integrated into a fourth category: terrestrial covers (Fig. 3). Landsat TM images recorded earlier than 1986 were not available, so in some cases the maps also include a fifth land cover category corresponding to the shrimp farms present since that time.

#### **2.3 Change detection analysis**

In the third step, the changes produced by shrimp farming in the Mexican coastal landscapes were assessed by overlaying the buffered shrimp farm polygons (t2) on the 1986- 1999 thematic maps (t1) following a post-classificatory analysis scheme (Mas, 1999, Berlanga-Robles et al. 2010; Berlanga-Robles & Ruiz-Luna, 2011), which outputs a matrix for change detection, identifying trends and the extent of variations on every cover presumably produced by shrimp farming (Fig. 3). Considering just the Gulf of California region, a similar analysis was performed only on mangroves, using a dataset produced with 1973 Landsat MSS images (60 m pixel size) developed in earlier studies (Ruiz-Luna et al., 2010).

#### **3. Results**

Based on the photo-interpretation process with Google Earth and ancillary data, a total of 273 polygons were identified, representing isolated farms or systems with more than one farm amounting to a total of approximately 80,000 ha. All structures identified as shrimp farms were included, even if the system was empty or out of operation. Sinaloa state has the largest area allocated for this industry, amounting to 51% of the estimated area, followed by Sonora, Nayarit and Tamaulipas, with 41, 6 and 1%, respectively (Table 1).

Regarding the transformations due to aquaculture, the main subsidiaries were those that integrate anthropic and vegetation cover other than that identifiable as wetland, namely, terrestrial coverage, with 46%, and saltmarsh, with 45%. Approximately 3% of the ponds were built on the shallow coastal lagoons and estuaries (water surface), and mangrove was the least modified cover (1%). The change in mangrove cover is estimated to be more than 1150 ha, mainly in Sinaloa (≈ 700 ha) and Nayarit (≈ 400), the states with the largest mangrove cover in the Mexican Pacific, which account for approximately 70,000 ha each (Ruiz-Luna et al., 2010). These states are also first in the execution of shrimp aquaculture

In the second step, performed by analysts different than those whose updated and prepared the shrimp farm polygons, the coastal landscape of four selected states before the advent of shrimp farming were characterized by means of thematic maps generated by the classification of Landsat TM images from 1986 to 1999, downloaded from the USGS Global Visualization Viewer portal (http://glovis.usgs.gov/). The imagery covering the shrimp farming area in the states of the Gulf of California comprises 14 Landsat TM images among paths 30 to 37 and rows 39 to 45. The area of Tamaulipas was covered with three images recorded in path 26 among rows 41 and 43. All the spectral bands except thermal infrared

The images underwent unsupervised classification using a K-means clustering technique (Richards & Jia, 1999). A 16 spectral cluster map was produced first, which was subsequently associated with natural covers represented by three coastal wetland types (aquatic surfaces, saltmarsh and mangroves), while other natural vegetation (dry forest, thorn scrub forest) and vegetation of anthropic origin (agriculture, settlements, lineal infrastructure) were integrated into a fourth category: terrestrial covers (Fig. 3). Landsat TM images recorded earlier than 1986 were not available, so in some cases the maps also include a fifth land cover category corresponding to the shrimp farms present since that time.

In the third step, the changes produced by shrimp farming in the Mexican coastal landscapes were assessed by overlaying the buffered shrimp farm polygons (t2) on the 1986- 1999 thematic maps (t1) following a post-classificatory analysis scheme (Mas, 1999, Berlanga-Robles et al. 2010; Berlanga-Robles & Ruiz-Luna, 2011), which outputs a matrix for change detection, identifying trends and the extent of variations on every cover presumably produced by shrimp farming (Fig. 3). Considering just the Gulf of California region, a similar analysis was performed only on mangroves, using a dataset produced with 1973 Landsat MSS images (60 m pixel size) developed in earlier studies (Ruiz-Luna et al., 2010).

Based on the photo-interpretation process with Google Earth and ancillary data, a total of 273 polygons were identified, representing isolated farms or systems with more than one farm amounting to a total of approximately 80,000 ha. All structures identified as shrimp farms were included, even if the system was empty or out of operation. Sinaloa state has the largest area allocated for this industry, amounting to 51% of the estimated area, followed by

Regarding the transformations due to aquaculture, the main subsidiaries were those that integrate anthropic and vegetation cover other than that identifiable as wetland, namely, terrestrial coverage, with 46%, and saltmarsh, with 45%. Approximately 3% of the ponds were built on the shallow coastal lagoons and estuaries (water surface), and mangrove was the least modified cover (1%). The change in mangrove cover is estimated to be more than 1150 ha, mainly in Sinaloa (≈ 700 ha) and Nayarit (≈ 400), the states with the largest mangrove cover in the Mexican Pacific, which account for approximately 70,000 ha each (Ruiz-Luna et al., 2010). These states are also first in the execution of shrimp aquaculture

Sonora, Nayarit and Tamaulipas, with 41, 6 and 1%, respectively (Table 1).

**2.2 Landscape characterization** 

**2.3 Change detection analysis** 

were used.

**3. Results** 


Table 1. Land use changes produced by shrimp farming in four states of Mexico. Area in hectares and corresponding proportion (%) in parenthesis. \*Some farms were built before 1986, the initial time for this study (t1), consequently, figures in this row represent no change after this date.

projects. It is important to highlight that shrimp aquaculture started prior to 1986, the date of the first Landsat image included in this analysis, which explains why 5% of the shrimp aquaculture use was unchaged in land use . It means that approximately 4000 ha of shrimp ponds had been constructed by 1986 on undetermined covers.

As most of the changes happened in the Gulf of California region, it is important to have look at Tamaulipas, the only representative of shrimp aquaculture in the Gulf of Mexico. No mangrove deforestation was associated with shrimp ponds, and the main subsidiary cover was terrestrial cover, amounting to 93% of the total area used for shrimp pond installation.

Based on the 1973 estimates for mangrove distribution proposed by Ruiz-Luna et al. (2010) for the Gulf of California region, the change detection analysis output some differences with the previous analysis, showing a slight reduction of the assessed mangrove loss for Nayarit and Sonora (Table 2). The mangrove change at Nayarit was 77 ha less, as evaluated with the 1973 map with respect to the 1986 map. The changes in Sonora were similar in both studies; even so, the reduction is 14 ha more with the 1986 map than that estimated with the 1973 map. The differences in both cases are approximately 15-20%. By contrast, the mangrove loss estimated for Sinaloa increased by approximately 40% when the 1973 map was analyzed, agreeing with a technical report published by Ruiz-Luna et al. (2005). Even so, the technical differences in both Landsat devices (MSS and TM) make an underestimation of the 1973 mangrove area possible due the low resolution of the Landsat MSS imagery (60 m) used to produce these maps, as noted by Ruiz-Luna et al. (2010). Thus, the differences among Nayarit and Sonora could be reduced, but in the case of Sinaloa, it could increase.


Table 2. Change detection matrix for land cover change from mangrove (1973) to shrimp farms (2010). Area in hectares and relative proportion (%) in parenthesis.

Impact of Shrimp Farming on Mangrove Forest and Other Coastal Wetlands: The Case of Mexico 25

Bangladesh (1952-1988)1 7500 978 6522 6522 6522 100 100 Thailand (1961-1996)2 367900 167582 200318 80000 66998 84 33

(1986-1992)3 1250 390 860 1490 790 53 92 Philippines (1997)a 4 29500017 25000017 45000 6940 3470 50 8 Ecuador (1969-1999)5 362700 149557 213143 10000 48649 49 23

Ecuador (1966-1982)6 4693 3294 1399 2331 931 40 67

(1986-1992)3 750 320 430 938 364 39 85

Honduras (1973-1992)7 30697 23937 6760 11515 4307 37 64 Indonesia (1997) a 4 420000017 315000017 1050000 20000 5320 27 1 Thailand (1997) a 4 28000017 24410017 35900 47755 9933 21 28

(1977-2005)8 19480 18610 870 4650 820 18 94 Taiwan (1997)a 4 -- -- -- 1407 173 12.3 --

2001)9 7644 7353 521 1900 230 12 44

Nam (1968-2003)10 19507 47614 14746 59684 5643 10 38

1997)11 910 710 200 170 10 6 5 India (1989-1999)12 46700017 44820017 18800 130000 6500 5 35

Mexico (1973-2000)13 89182 75042 14140 3208 102 3 1

2003)14 75364 84912 --b 46882 790 2 --

(1984-1999)15 7558 7217 341 3192 23 1 7

2005)16 21983 21873 110 9949 26 <1 24

t1 and t2, initial and final mangrove area in every period study. A Loss, differences in mangrove cover (ha) in the study period. B Ponds, area (ha) occupied by shrimp ponds. C Conv., conversion from mangrove to shrimp ponds (area in ha). %1, proportion of ponds built on mangrove = (C/B)100. %2, proportion of mangrove loss caused by shrimp farming = (C/A)100. a Only considering intensive

shrimp farms. b Authors found a positive change in Sinaloa's mangrove cover. Sources: 1Hossain (2001); 2Aksornkoae and Tokrisna (2004); 3Bélard et al. (2006); 4Kongkeo (1997); 5Bravo (2003); 6Terchunian et al.

(1986); 7Dewalt et al. (1996); 8 Sudhaka-Reddy & Roy (2008); 9Berlanga-Robles & Ruiz-Luna (2006); 10Binh et al. (2005); 11Ruiz-Luna & Berlanga-Robles (2003); 12Hein (2002); 13Berlanga-Robles & Ruiz-Luna (2007); 14De la Fuente & Carrera (2005); 15Alonso-Pérez (2003); 16Berlanga-Robles et al. (2005); 17FAO

Table 4. Changes in mangrove cover related to shrimp farming in Asia and America.

Mangrove area (ha) A B C

t1 t2 Loss Ponds Conv %1 %2

Country/Region (period)

Chakaria Sunderban,

Tien Hai, Viet Nam

Machala-Pto. Bolivar,

Giao Thuy, Viet Nam

Godovari delta, India

San Blas, Mexico (1973-

CaiNuoc district, Viet

Mazatlan, Mexico (1973-

Marismas Nacionales,

Sinaloa, Mexico (1992-

Ceuta Lagoon, Mexico

North of Sinaloa (1986-

(2007).

Golfo de Fonseca,

Mexican laws protect mangrove forests (Federal Wildlife Law 2000, NOM-022-SEMARNAT-2003, NOM-059-SEMARNAT-2010). These laws declare all mangrove species endangered, and they forbid changes on this cover while prohibiting adjacent economic activities (with some exemptions). Therefore, we defined a 100-m buffer zone around the shrimp farm polygons to assess the impact on mangroves within this fringe restricted by law. Using this criterion, the impacted area is almost twice the preceding figure, and Sinaloa was again the most unsafe area. The results of this analysis are shown in Table 3.


Table 3. Shrimp farms adjacent to mangrove forests in some Mexican states and mangrove extent (ha) inside the 100 m fringe banned by law for any economic activity. Estimations are based on a 100 m buffer created around the shrimp farm polygons and overlaid on mangrove thematic maps.

Even when a farm's design excluded the polygon from the mangrove cover, the shrimp farms were sometimes constructed in the vicinity of mangroves, thus transgressing some environmental regulations. From our results, close to 60% of the total analyzed shrimp farms were in proximity with mangroves, almost doubling the lost area estimated here for this vegetation if the 100 m fringe is considered. Sinaloa and Nayarit, both with the largest mangrove coverage, were the states with the highest interaction between polygons and the forbidden perimeter, affecting more than 80% of the farms in the case of Nayarit.

#### **4. Mexican shrimp farming in the international context**

Comparing the observed conditions of Mexican shrimp farming with other producing countries worldwide highlights the fact that most of the declarations about mangrove deforestation by shrimp farming are not properly documented. Documents with data and descriptions of the technical process to assess mangrove deforestation are limited and, in some cases, only generalize observed trends. From the available information, it was possible to analyze some cases from Asia and America, including six cases in Mexico (Table 4).

At first sight, the situation of the Mexican states can be roughly compared with that from other countries. In some regions of India, Bangladesh and Vietnam, though not necessarily at the country level, shrimp ponds are practically the only cause of deforestation, with rates between 85 and 100%, even when those ponds generally represent a small to medium fraction (17.6 to 53%) of the activity (Table 4).

Shrimp farming growth in Latin America also had negative effects on mangrove cover, particularly in Ecuador and Honduras (Gulf of Fonseca), with a decline in total mangrove cover of approximately 27% and 22% between 1969-1995 and 1973-1992, respectively (DeWalt et al., 1996; Tobey et al., 1998). These references agree with the present analysis,


Mexican laws protect mangrove forests (Federal Wildlife Law 2000, NOM-022-SEMARNAT-2003, NOM-059-SEMARNAT-2010). These laws declare all mangrove species endangered, and they forbid changes on this cover while prohibiting adjacent economic activities (with some exemptions). Therefore, we defined a 100-m buffer zone around the shrimp farm polygons to assess the impact on mangroves within this fringe restricted by law. Using this criterion, the impacted area is almost twice the preceding figure, and Sinaloa was again the

Nayarit 43 81.4 426 Sinaloa 163 68.7 1635 Sonora 45 26.7 113 Tamaulipas 22 4.5 2 Total 273 58.6 2176

Table 3. Shrimp farms adjacent to mangrove forests in some Mexican states and mangrove extent (ha) inside the 100 m fringe banned by law for any economic activity. Estimations are

Even when a farm's design excluded the polygon from the mangrove cover, the shrimp farms were sometimes constructed in the vicinity of mangroves, thus transgressing some environmental regulations. From our results, close to 60% of the total analyzed shrimp farms were in proximity with mangroves, almost doubling the lost area estimated here for this vegetation if the 100 m fringe is considered. Sinaloa and Nayarit, both with the largest mangrove coverage, were the states with the highest interaction between polygons and the

Comparing the observed conditions of Mexican shrimp farming with other producing countries worldwide highlights the fact that most of the declarations about mangrove deforestation by shrimp farming are not properly documented. Documents with data and descriptions of the technical process to assess mangrove deforestation are limited and, in some cases, only generalize observed trends. From the available information, it was possible to analyze some cases from Asia and America, including six cases in Mexico (Table 4).

At first sight, the situation of the Mexican states can be roughly compared with that from other countries. In some regions of India, Bangladesh and Vietnam, though not necessarily at the country level, shrimp ponds are practically the only cause of deforestation, with rates between 85 and 100%, even when those ponds generally represent a small to medium

Shrimp farming growth in Latin America also had negative effects on mangrove cover, particularly in Ecuador and Honduras (Gulf of Fonseca), with a decline in total mangrove cover of approximately 27% and 22% between 1969-1995 and 1973-1992, respectively (DeWalt et al., 1996; Tobey et al., 1998). These references agree with the present analysis,

based on a 100 m buffer created around the shrimp farm polygons and overlaid on

forbidden perimeter, affecting more than 80% of the farms in the case of Nayarit.

**4. Mexican shrimp farming in the international context** 

fraction (17.6 to 53%) of the activity (Table 4).

polygons % of farms adjacent Mangrove in 100 m

zone

most unsafe area. The results of this analysis are shown in Table 3.

State Shrimp farm

mangrove thematic maps.


t1 and t2, initial and final mangrove area in every period study. A Loss, differences in mangrove cover (ha) in the study period. B Ponds, area (ha) occupied by shrimp ponds. C Conv., conversion from mangrove to shrimp ponds (area in ha). %1, proportion of ponds built on mangrove = (C/B)100. %2, proportion of mangrove loss caused by shrimp farming = (C/A)100. a Only considering intensive shrimp farms. b Authors found a positive change in Sinaloa's mangrove cover. Sources: 1Hossain (2001); 2Aksornkoae and Tokrisna (2004); 3Bélard et al. (2006); 4Kongkeo (1997); 5Bravo (2003); 6Terchunian et al. (1986); 7Dewalt et al. (1996); 8 Sudhaka-Reddy & Roy (2008); 9Berlanga-Robles & Ruiz-Luna (2006); 10Binh et al. (2005); 11Ruiz-Luna & Berlanga-Robles (2003); 12Hein (2002); 13Berlanga-Robles & Ruiz-Luna (2007); 14De la Fuente & Carrera (2005); 15Alonso-Pérez (2003); 16Berlanga-Robles et al. (2005); 17FAO (2007).

Table 4. Changes in mangrove cover related to shrimp farming in Asia and America.

Impact of Shrimp Farming on Mangrove Forest and Other Coastal Wetlands: The Case of Mexico 27

We must emphasize that, even with the largest mangrove extent and the best developed area being located in the Yucatan Peninsula (Campeche, Yucatan, Quintana Roo and Chiapas states), which accounts for approximately 60% of the mangrove forests in Mexico (Acosta et al., 2009), the shrimp farming in this area represents less than 1% of the total extent and production of Mexico (CONAPESCA, 2010). For this reason, neither of the abovementioned states were included in the analysis. The four states analyzed here currently amount to 97% of the area dedicated to shrimp farming (CONAPESCA, 2010),

The present findings indicate that Mexico has approximately 82 500 ha dedicated to shrimp production, though not all of this area is necessarily in operation. From these areas, between 1.5% and 1.7% could be constructed on mangrove cover, removing approximately 1300 ha, which is equivalent to less than 1.0% of the 770 000 ha of mangrove reported by the Mexican National Commission for the Knowledge and Use of Biodiversity (Acosta et al., 2009). These results greatly contrast with other tropical and subtropical countries, where shrimp farming has been responsible for of most of the mangrove deforestation (Bangladesh, Ecuador) or an important part of it (Honduras, India, Thailand). However, although shrimp farming could not be considered a risk to Mexican mangrove cover, it has been established on other important coastal wetlands rarely mentioned in literature (estuaries, lagoon, saltmarsh).

The worldwide estimation of mangrove deforestation caused by shrimp farming is difficult because not all producing countries have reliable data at the national level. The analysis of the literature shows that in many instances, nationwide or global estimates are based on local or regional case studies or are extrapolated from foreign conditions, such as those from Thailand and Ecuador, or even Indonesia, where mangrove loss has been severe though

In agreement with FAO (2007), the global mangrove cover declined from approximately 19 million ha in 1980 to almost 16 million ha in 2000, while the shrimp pond area was 1.25 million ha in 1998 (Rönnbäck, 2002). Considering the extreme case of all the shrimp ponds constructed on mangroves areas, this activity could be responsible for 41% of mangrove loss. As observed here, in approximately 70% of the cases, the shrimp farming accounted for less than 50% of deforestation, and within this 70%, the half has contributed with less than 30% of mangrove decline. Considering both scenarios, shrimp farming could be directly

The Mexican case could be a result of a postponed development of the industry, with a delay of approximately 10 to 15 years in respect to other countries due to legal constraints. After this late beginning, the industry grew rapidly even while acknowledging environmental problems and is now among the ten top producers, second to Latin America, which is after Ecuador. Consequently, shrimp farming has been responsible for mangrove deforestation but not at the same level observed in the former shrimp producers. Regrettably, the risk has been transferred to other coastal wetlands, as 46% of the ponds have been built on saltmarshes. This land cover is more suitable for shrimp pond construction farms because of soil characteristics and topography. In addition, these wetlands are cheap in economic terms, as they are considered unproductive, and they are barely protected by Mexican laws. Studies on saltmarsh loss show that 12% of this cover in Nayarit and Sinaloa was lost because of 25 000 ha of ponds (Berlanga-Robles et al., 2011). Even more, the impact of shrimp farming on the coastal landscapes goes beyond the direct

responsible for 20.8 to 12.5% of the mangrove loss between 1980 and 2000.

which is enough to document the impact of this activity on mangrove cover.

mostly independent of shrimp farming activity.

which reveals that Ecuador's mangrove loss and conversion was close to 90% of approximately 54000 ha at the nation level and 67% at the regional level (Machala-Puerto Bolivar), where mangrove loss was estimated at approximately 1400 ha. Honduras in the early 1970s accounted for more than 11500 ha of shrimp ponds in the Gulf of Fonseca, approximately 65% of which were constructed on mangrove sites.

In Mexico, the highest conversion ratio from mangrove to shrimp ponds has been recorded for San Blas, at Nayarit state, and northern Sinaloa, with 44.1% and 23.6%, respectively, amounting to a total of approximately 260 converted hectares. In relative terms, these numbers represent 12.1% and 0.3% of the total pond area constructed by region, respectively, at approximately 12 000 ha in total. Other studies in Mexico on mangrove conversion attributable to shrimp farming show output ratios less than 7% of lost mangrove cover. It is also remarkable that two independent works conducted in Sinaloa state found an increase in the mangrove cover, and, with some differences, they even found that the mangrove area occupied by shrimp farm developments represents between 1.7 and 2.2% of a pond surface estimated above 40 000 ha (De la Fuente & Carrera, 2005; Ruiz-Luna et al., 2005).

#### **5. Discussion**

Intense debate about the environmental impacts caused by shrimp farming has been engaged in Mexico since the beginning of this activity, particularly by environmentalists, regarding the denunciation of the environmental risks associated with shrimp farming development. Considering the international background of this issue and bearing in mind the importance of the environmental services offered by mangroves and the possible impact caused by land cover changes, the general opinion is that Mexico could confront environmental risks similar to Indonesia, Philippines, Thailand and Ecuador, where extensive deforestation of mangrove forests is associated with the construction of shrimp ponds.

This perception has been maintained and consistently declared even though there are few studies documenting changes in mangrove at a national extent or the possible causes of mangrove deforestation when it is proved. It is common that some differences in mangrove cover estimations obtained by the extrapolation of local values or using different inputs and evaluation techniques would be misinterpreted as deforestation (Ruiz-Luna et al. 2008).

Thus, the studies conducted by Hernández-Cornejo & Ruiz-Luna (2000), Alonso-Pérez et al. (2003), De la Fuente & Carrera (2005), Ruiz-Luna et al. (2005), Berlanga-Robles & Ruiz-Luna (2007), and Berlanga-Robles et al. (2011), among others, have attempted to verify the extent and intensity of the impact of shrimp farming in Mexico.

Most of the above papers mainly describe the conditions observed in Sinaloa and Nayarit, in northwest Mexico. This paper is the first attempt to document changes at a nationwide level based on our own and other authors findings obtained with remote sensing techniques, analyzing very high spatial resolution satellite imagery (Landsat, Spot, QickBird, GeoEye) and updating the existing information up to 2010. The main restriction imposed to these studies is the lack of reference data to validate the accuracy of the earlier dates' estimates. Even so, the similitude among the results from independent analyses give confidence to the general trends followed by shrimp farm growth and its impact on mangrove forests in Mexico, making a comparison possible with analogous developments elsewhere.

which reveals that Ecuador's mangrove loss and conversion was close to 90% of approximately 54000 ha at the nation level and 67% at the regional level (Machala-Puerto Bolivar), where mangrove loss was estimated at approximately 1400 ha. Honduras in the early 1970s accounted for more than 11500 ha of shrimp ponds in the Gulf of Fonseca,

In Mexico, the highest conversion ratio from mangrove to shrimp ponds has been recorded for San Blas, at Nayarit state, and northern Sinaloa, with 44.1% and 23.6%, respectively, amounting to a total of approximately 260 converted hectares. In relative terms, these numbers represent 12.1% and 0.3% of the total pond area constructed by region, respectively, at approximately 12 000 ha in total. Other studies in Mexico on mangrove conversion attributable to shrimp farming show output ratios less than 7% of lost mangrove cover. It is also remarkable that two independent works conducted in Sinaloa state found an increase in the mangrove cover, and, with some differences, they even found that the mangrove area occupied by shrimp farm developments represents between 1.7 and 2.2% of a pond surface

Intense debate about the environmental impacts caused by shrimp farming has been engaged in Mexico since the beginning of this activity, particularly by environmentalists, regarding the denunciation of the environmental risks associated with shrimp farming development. Considering the international background of this issue and bearing in mind the importance of the environmental services offered by mangroves and the possible impact caused by land cover changes, the general opinion is that Mexico could confront environmental risks similar to Indonesia, Philippines, Thailand and Ecuador, where extensive deforestation of mangrove forests is associated with the construction of shrimp

This perception has been maintained and consistently declared even though there are few studies documenting changes in mangrove at a national extent or the possible causes of mangrove deforestation when it is proved. It is common that some differences in mangrove cover estimations obtained by the extrapolation of local values or using different inputs and evaluation techniques would be misinterpreted as deforestation (Ruiz-Luna et al. 2008).

Thus, the studies conducted by Hernández-Cornejo & Ruiz-Luna (2000), Alonso-Pérez et al. (2003), De la Fuente & Carrera (2005), Ruiz-Luna et al. (2005), Berlanga-Robles & Ruiz-Luna (2007), and Berlanga-Robles et al. (2011), among others, have attempted to verify the extent

Most of the above papers mainly describe the conditions observed in Sinaloa and Nayarit, in northwest Mexico. This paper is the first attempt to document changes at a nationwide level based on our own and other authors findings obtained with remote sensing techniques, analyzing very high spatial resolution satellite imagery (Landsat, Spot, QickBird, GeoEye) and updating the existing information up to 2010. The main restriction imposed to these studies is the lack of reference data to validate the accuracy of the earlier dates' estimates. Even so, the similitude among the results from independent analyses give confidence to the general trends followed by shrimp farm growth and its impact on mangrove forests in

Mexico, making a comparison possible with analogous developments elsewhere.

and intensity of the impact of shrimp farming in Mexico.

approximately 65% of which were constructed on mangrove sites.

**5. Discussion** 

ponds.

estimated above 40 000 ha (De la Fuente & Carrera, 2005; Ruiz-Luna et al., 2005).

We must emphasize that, even with the largest mangrove extent and the best developed area being located in the Yucatan Peninsula (Campeche, Yucatan, Quintana Roo and Chiapas states), which accounts for approximately 60% of the mangrove forests in Mexico (Acosta et al., 2009), the shrimp farming in this area represents less than 1% of the total extent and production of Mexico (CONAPESCA, 2010). For this reason, neither of the abovementioned states were included in the analysis. The four states analyzed here currently amount to 97% of the area dedicated to shrimp farming (CONAPESCA, 2010), which is enough to document the impact of this activity on mangrove cover.

The present findings indicate that Mexico has approximately 82 500 ha dedicated to shrimp production, though not all of this area is necessarily in operation. From these areas, between 1.5% and 1.7% could be constructed on mangrove cover, removing approximately 1300 ha, which is equivalent to less than 1.0% of the 770 000 ha of mangrove reported by the Mexican National Commission for the Knowledge and Use of Biodiversity (Acosta et al., 2009). These results greatly contrast with other tropical and subtropical countries, where shrimp farming has been responsible for of most of the mangrove deforestation (Bangladesh, Ecuador) or an important part of it (Honduras, India, Thailand). However, although shrimp farming could not be considered a risk to Mexican mangrove cover, it has been established on other important coastal wetlands rarely mentioned in literature (estuaries, lagoon, saltmarsh).

The worldwide estimation of mangrove deforestation caused by shrimp farming is difficult because not all producing countries have reliable data at the national level. The analysis of the literature shows that in many instances, nationwide or global estimates are based on local or regional case studies or are extrapolated from foreign conditions, such as those from Thailand and Ecuador, or even Indonesia, where mangrove loss has been severe though mostly independent of shrimp farming activity.

In agreement with FAO (2007), the global mangrove cover declined from approximately 19 million ha in 1980 to almost 16 million ha in 2000, while the shrimp pond area was 1.25 million ha in 1998 (Rönnbäck, 2002). Considering the extreme case of all the shrimp ponds constructed on mangroves areas, this activity could be responsible for 41% of mangrove loss. As observed here, in approximately 70% of the cases, the shrimp farming accounted for less than 50% of deforestation, and within this 70%, the half has contributed with less than 30% of mangrove decline. Considering both scenarios, shrimp farming could be directly responsible for 20.8 to 12.5% of the mangrove loss between 1980 and 2000.

The Mexican case could be a result of a postponed development of the industry, with a delay of approximately 10 to 15 years in respect to other countries due to legal constraints. After this late beginning, the industry grew rapidly even while acknowledging environmental problems and is now among the ten top producers, second to Latin America, which is after Ecuador. Consequently, shrimp farming has been responsible for mangrove deforestation but not at the same level observed in the former shrimp producers. Regrettably, the risk has been transferred to other coastal wetlands, as 46% of the ponds have been built on saltmarshes. This land cover is more suitable for shrimp pond construction farms because of soil characteristics and topography. In addition, these wetlands are cheap in economic terms, as they are considered unproductive, and they are barely protected by Mexican laws. Studies on saltmarsh loss show that 12% of this cover in Nayarit and Sinaloa was lost because of 25 000 ha of ponds (Berlanga-Robles et al., 2011). Even more, the impact of shrimp farming on the coastal landscapes goes beyond the direct

Impact of Shrimp Farming on Mangrove Forest and Other Coastal Wetlands: The Case of Mexico 29

Berlanga-Robles C.A. & Ruiz-Luna, A. (2006) Assessment of landscape changes and their

Berlanga-Robles C.A. & Ruiz-Luna, A. (2007) Análisis de las tendencias de cambio del

Berlanga-Robles, García-Campos, R.R., López-Blanco J. & Ruiz-Luna, A. (2010) Patrones de

Berlanga-Robles, C.A., Ruiz-Luna A. Bocco G. & Vekerdy Z. (2011). Spatial analysis of the

Binh T.N.K.D., Vromant, N., Hung, N.T., Hens, L. & Boon E.K., 2005. Land cover changes

Boyd, C.E. & Clay, J.W. (1998). Shrimp aquaculture and the environment. Scientific

Bravo, E. (2003) La industria camaronera en Ecuador, Globalización y Agricultura. Jornadas

CONAPESCA (2009) Anuario Estadístico de Acuacultura y Pesca Edición 2007. Comisión

CONAPESCA (2010) Anuario Estadístico de Acuacultura y Pesca Edición 2008. Comisión

De la Fuente L.G. & Carrera, G.E. (2005) Cambio de Usos del Suelo en la Zona Costera del

DeWalt, B., P. Vergne, P. & Hardin, M. (1996). Shrimp aquaculture development and the

FAO, (2007). The World's Mangroves 1980-2005, FAO Forestry Paper 153, ISBN

Hernández-Cornejo R. & Ruiz-Luna, A. (2000) Development of shrimp farming in the

issues, and perspectives. Ocean & Coastal Management, 43, 597-607. Hossain, MdS., Lin, C.K, Hussain & M.Z. (2001) Goodbye Chakaria Sunderban: The oldest mangrove forest. The Society of Wetland Scientists Bulletin, 18, 3, pp. 19-22. Kongkeo, H. (1997) Comparison of intensive shrimp farming systems in Indonesia, Philippines, Taiwan and Thailand. Aquaculture Research 28, pp 789-796. Kungvankij, P., Chua, T.E., Pudadera, B.J. Jr., Corre, K.G., Borlongan, E., Alava, Tiro, L.B. Jr.,

Management. FAO Training Series No. 2, http://www.fao.org

environment: People, mangroves and fisheries in the Gulf of Fonseca. World

coastal zone of southern Sinaloa (Mexico): operating characteristics, environmental

Potestas, I.O. & Talean, G.A. (1986). Shrimp Culture: Pond Design, Operation and

Mas, J.F. (1999) Monitoring land-cover changes: a comparison of change detection techniques. International Journal of Remote Sensing, 20(1), pp. 139-152.

imagery analysis. Ciencias Marinas, 32, 3, pp. 523-538.

2000). Investigaciones Geográficas, 72, pp. 7-22.

Development and Sustainability, 7, pp. 519-536.

para la Soberanía Alimentaria, Barcelona, 2003 june.

Estado de Sinaloa, Ducks Unlimited de México, México.

FAO, (2011). Global Aquaculture Production 1950-2009, accessed 22-07-11,

Nacional de Acuacultura y Pesca, Mexico.

Nacional de Acuacultura y Pesca, Mexico.

Development, 24, 7, pp. 1193-12098.

9789251058565, Rome.

http://www.fao.org

Mexico. Ocean & Coastal Management, 54, pp. 535-543.

1, pp. 29-46.

American, 278, 58-65.

effects on the San Blas estuarine system, Nayarit (Mexico), through Landsat

bosque de mangle del sistema lagunar Teacapán-Agua Brava, México. Una aproximación con el uso de imágenes de satélite Landsat. Universidad y ciencia, 23,

cambio de coberturas y usos del suelo en la región costa norte de Nayarit (1973-

impact of shrimp culture on the coastal wetlands on the Northern coast of Sinaloa,

between 1968 and 2003 in Cai Nuoc Ca Mau Peninsula, VietNam. Environment

loss of wetlands because the ponds themselves and mostly the linear infrastructure necessary for the operation of farms, such as canals and roads, have a strong impact on the connectivity of coastal landscapes, fragmenting saltmarsh habitat, modifying the water flows and sediment supplies in the intertidal zone, and threatening the overall stability of coastal wetlands (Berlanga-Robles et al., 2011).

In conclusion, the shrimp aquaculture in Mexico is not the main cause of mangrove deforestation, as has happened with other countries. Even so, the industry is far from sustainable because almost half of the pond area has resulted in the direct removal of other natural wetlands. Also, the entire associated infrastructure interrupts local and regional ecological process by fragmentation of the intertidal zone (Berlanga-Robles et al., 2011). Finally, even when those farms do not have contact with the mangrove cover, a significant proportion of them were built near mangrove patches, particularly in Sinaloa and Nayarit, infringing upon legal rules and threatening the 100 m fringe established by Mexican law. To move toward real sustainability, some areas must be restored in agreement with laws. Future developments must require an ecologic and economic reevaluation of coastal wetlands prior to operation to avoid new impacts and to provide the systems with the essential connectivity among wetlands and other wetlands, maintaining the water and sediment flows in the intertidal zone.

#### **6. Acknowledgment**

The authors acknowledge the National Commission for Fisheries and Aquaculture-Mexico (CONAPESCA) for provided us his database with the shrimp farms polygons. Landsat images used in this study were provided by U. S. Geological Survey Resources Observation and science Center (USGS-EROS).

#### **7. References**


loss of wetlands because the ponds themselves and mostly the linear infrastructure necessary for the operation of farms, such as canals and roads, have a strong impact on the connectivity of coastal landscapes, fragmenting saltmarsh habitat, modifying the water flows and sediment supplies in the intertidal zone, and threatening the overall stability of

In conclusion, the shrimp aquaculture in Mexico is not the main cause of mangrove deforestation, as has happened with other countries. Even so, the industry is far from sustainable because almost half of the pond area has resulted in the direct removal of other natural wetlands. Also, the entire associated infrastructure interrupts local and regional ecological process by fragmentation of the intertidal zone (Berlanga-Robles et al., 2011). Finally, even when those farms do not have contact with the mangrove cover, a significant proportion of them were built near mangrove patches, particularly in Sinaloa and Nayarit, infringing upon legal rules and threatening the 100 m fringe established by Mexican law. To move toward real sustainability, some areas must be restored in agreement with laws. Future developments must require an ecologic and economic reevaluation of coastal wetlands prior to operation to avoid new impacts and to provide the systems with the essential connectivity among wetlands and other wetlands, maintaining the water and

The authors acknowledge the National Commission for Fisheries and Aquaculture-Mexico (CONAPESCA) for provided us his database with the shrimp farms polygons. Landsat images used in this study were provided by U. S. Geological Survey Resources Observation

Acosta-Velázquez, J., Rodríguez-Zuñiga, T., Reyes-Díaz-Gallegos, J., Cerdeira-Estrada, S.,

Aksornkoae S. & Tokrisna, R. (2004). Overview of shrimp farming and mangrove loss in

Bélard, M., Goïta, K., Bonn, F. & Pham, T.T.H. (2006) Assessment of land-cover changes

farming. Environmental Management 29, 3, pp. 349-359.

Sathirathai, S., pp. 37-51, Edward Elgar, ISBN 1843766019, Great Britain. Alonso-Pérez, F., Ruiz-Luna, A., Turner, J., Berlanga-Robles, C.A. & Mitchelson-Jacob, M.G.

Troche-Souza, C., Cruz, I., Ressl, R. & Jiménez, R. (2009) Assessing a nationwide spatial distribution of mangrove forest for Mexico: an analysis with high resolution images. *33rd International Symposium on Remote Sensing of Environment*, Stressa,

Thailand, In: *Shrimp Farming and Mangrove Loss in Thailand*, Barbier, E.B.

(2003) Land cover changes in the Ceuta coastal lagoon system, Sinaloa, Mexico: assessing the effect of the establishment of shrimp aquaculture. *Ocean & Coastal* 

related to shrimp aquaculture using remote sensing data: a case study in the Gian Thuy Distric, Vietnam. *International Journal of Remote Sensing*, 27, pp. 1491-1510. Hein, L. (2002). Toward improved environmental and social management of Indian shrimp

coastal wetlands (Berlanga-Robles et al., 2011).

sediment flows in the intertidal zone.

and science Center (USGS-EROS).

Italy, 2009 may.

*Management*, 46, pp. 583-600.

**6. Acknowledgment** 

**7. References** 


**3** 

*Philippines* 

**Mangrove Revegetation Potentials of** 

*1Br. Alfred Shields FSC Marine Station, De La Salle University, Manila*

Maricar S. Samson1,2 and Rene N. Rollon3

*2School of Environmental Science and Management,* 

*3Institute of Environmental Science and Meteorology,* 

*University of the Philippines Los Baños* 

*University of the Philippines Diliman* 

**Brackish-Water Pond Areas in the Philippines** 

The Philippines is one of the countries with the most number of true – mangrove species (about 42 species, 18 families, **Table 1**) (Primavera, 2004; Spalding et al 2010; Polidoro et al 2010). However Philippine mangrove forests suffered greatly from anthropogenic activities, i.e. cutting for firewood and charcoal, siltation caused by upland deforestation, and conversion of mangrove areas to shrimp ponds, fishponds and salt ponds (Primavera 1991, 1995, 2000; Field, 1998; FAO, 2003, 2007). From 1918 (~450,000) to 1998 (112,400), mangrove cover declined by more than 75% (**Figure 1**). In 2007, the remaining mangrove areas in the Philippines was estimated at 289,350 hectares (DENR-NAMRIA 2007), a value which is 61% (176,950) higher than 1998 estimate. However, most of these are estimates based on satellite

The typical historical zonation of mangrove species in the Philippines follows that described by Duke et al in 1998 for mangroves found along Daintee River in Australia. Species with pneumatophores are commonly found at the low-intertidal; prop- and knee roots species are in the mid-intertidal; and buttress or plank root species are at the high intertidal area (**Figure 2a**). However due to the aforementioned large scale conversion to aquaculture

Of the total mangrove areas that were deforested, sixty-eight percent were converted to brackish-water ponds (Primavera, 1995, 2000). One of the legal instrument of operation of brackish-water ponds in the Philippines is the Fishpond Lease Agreement (FLA) that is being granted by the Philippine Bureau of Fisheries and Aquatic Resources (BFAR) under the Department of Agriculture (DA). In 2007, there were 59,923 hectares of potential brackish-water ponds with FLA belonging to 4,386 registered operators (BFAR, n.d.). However, the license agreement of almost 65% (39,152 ha) of these brackish-water ponds with FLA are already expired and as of the list posted in December 2010 had not been renewed. **Table 2** presents the details of the top 10 provinces in terms of the area with

ponds, the mangrove communities at the middle zone were diminished (**Figure 2b**).

**1. Introduction** 

images that need to be validated on field.

expired FLA licenses in the Philippines.


Maricar S. Samson1,2 and Rene N. Rollon3

*1Br. Alfred Shields FSC Marine Station, De La Salle University, Manila 2School of Environmental Science and Management, University of the Philippines Los Baños 3Institute of Environmental Science and Meteorology, University of the Philippines Diliman Philippines* 

#### **1. Introduction**

30 Aquaculture and the Environment - A Shared Destiny

Ponce-Palafox JT, Ruiz-Luna A, Castillo-Vargasmachuca S, García-Ulloa M & Arredondo-

Primavera, J.H. (2006). Overcoming the impacts of aquaculture on the coastal zone. Ocean &

Richards J.A., Jia, X. (1999) Remote Sensing Digital Image Analysis, Springer, ISBN

Rönnbäck, P. (2002) Environmentally Sustainable Shrimp Aquaculture, Swedish Society for

Ruiz-Luna, A. & Berlanga-Robles, C.A. (2003) Land use, land cover changes and coastal

Ruiz-Luna A., Acosta-Velázquez, J., Monzalvo-Santos, I.K. & Berlanga-Robles, C.A. (2005)

Ruiz-Luna, A. Acosta-Velázquez J. & Berlanga-Robles, C.A. (2008). On the reliability of the

Ruiz-Luna, A., Cervantes E.A., & Berlanga-Robles C.A. (2010) Assessing distribution

Sudhaka-Reddy, C. & Roy A. (2008). Assessment of three decade vegetation dynamics in

Terchunian, A., Klemas, V., Segovia, A., Alvarez, A. Vasconez, B. & Guerrero, L., (1986)

Tobey, J., Clay J. & Vergne, P. (1998) Maintaining Balance: The Economic, Environmental,

Research Journal of Environmental Sciences, 2, 2, pp. 108-115.

Environmental management, 10, 3, pp. 345-350.

lagoon surface reduction associated with urban growth in northwest Mexico.

*Evaluación de la cobertura de manglar, estructura forestal y determinación del impacto potencial por el establecimiento de granjas camaronícolas*, Instituto Sinaloense de

data of the extent of mangroves: A case study in Mexico. Ocean & Coastal

patterns, extent, and current Condition of northwest Mexico mangroves Wetlands,

mangroves of Godavari Delta, India using multi-temporal satellites data and SIG.

Mangrove mapping in Ecuador: the Impact of shrimp pond construction.

and Social Impacts of Shrimp farming in Latin America, Coastal Management Report #2202, Coastal Resources Center at the University of Rhode Island,

Nature Conservation, http://www.naturskyddsforeningen.se

Management, 54, pp. 507-513

3540648607, Berlin.

Coastal Management, 49, pp. 531-545.

Landscape Ecology, 18, pp. 159-171.

Acuacultura (ISA-Sinaloa), México.

Management, 51, pp. 342-351.

30, pp. 717-723.

http://crc.uri.edu

Figueroa J.L. (2011). Technical, economics and environmental analysis of semiintensive shrimp (Litopenaeus vannamei) farming in Sonora, Sinaloa and Nayarit states, at the east coast of the Gulf of California, México. Ocean & Coastal

> The Philippines is one of the countries with the most number of true – mangrove species (about 42 species, 18 families, **Table 1**) (Primavera, 2004; Spalding et al 2010; Polidoro et al 2010). However Philippine mangrove forests suffered greatly from anthropogenic activities, i.e. cutting for firewood and charcoal, siltation caused by upland deforestation, and conversion of mangrove areas to shrimp ponds, fishponds and salt ponds (Primavera 1991, 1995, 2000; Field, 1998; FAO, 2003, 2007). From 1918 (~450,000) to 1998 (112,400), mangrove cover declined by more than 75% (**Figure 1**). In 2007, the remaining mangrove areas in the Philippines was estimated at 289,350 hectares (DENR-NAMRIA 2007), a value which is 61% (176,950) higher than 1998 estimate. However, most of these are estimates based on satellite images that need to be validated on field.

> The typical historical zonation of mangrove species in the Philippines follows that described by Duke et al in 1998 for mangroves found along Daintee River in Australia. Species with pneumatophores are commonly found at the low-intertidal; prop- and knee roots species are in the mid-intertidal; and buttress or plank root species are at the high intertidal area (**Figure 2a**). However due to the aforementioned large scale conversion to aquaculture ponds, the mangrove communities at the middle zone were diminished (**Figure 2b**).

> Of the total mangrove areas that were deforested, sixty-eight percent were converted to brackish-water ponds (Primavera, 1995, 2000). One of the legal instrument of operation of brackish-water ponds in the Philippines is the Fishpond Lease Agreement (FLA) that is being granted by the Philippine Bureau of Fisheries and Aquatic Resources (BFAR) under the Department of Agriculture (DA). In 2007, there were 59,923 hectares of potential brackish-water ponds with FLA belonging to 4,386 registered operators (BFAR, n.d.). However, the license agreement of almost 65% (39,152 ha) of these brackish-water ponds with FLA are already expired and as of the list posted in December 2010 had not been renewed. **Table 2** presents the details of the top 10 provinces in terms of the area with expired FLA licenses in the Philippines.

Fig. 1. Estimated extent of mangrove areas in the Philippines from 1918 (around 450,000

Table 2. Top 10 provinces in terms of the area with expired FLA licenses in the Philippines. It has long been noted by various authors that most of the brackish-water ponds in the Philippines are either idle, abandoned, underutilized and in an unproductive state (Primavera and Agbayani 1997; Primavera 2000; Yap 2007; Samson and Rollon 2008; Primavera et al, 2012). There had been efforts to promote the reversion of these ponds to mangrove areas however the implementing rules and regulations had been unclear, if not nonexistent. In most cases, holders of FLA certificates are unwilling to yield the pond area for mangrove restoration (Yap, 2007; Samson and Rollon 2008). These underutilized ponds

hectares) to 2007 (around 289,350 hectares).


Table 1. List of true mangrove species in the Philippines (Spalding et al, 20101; Polidoro et al, 20102).

**FAMILY1 SPECIES1,2**

*Acanthus ilicifolius*

*Avicennia marina Avicennia officinalis Avicennia rumphiana*

*Camptostemon schultzii*

*Lumnitzera racemosa*

*Xylocarpus moluccensis*

*Acrostichum speciosum*

*Bruguiera exaristata Bruguiera gymnorhiza Bruguiera hainesii Bruguiera parviflora Bruguiera sexangula Ceriops decandra Ceriops tagal Kandelia obovata Rhizophora apiculata Rhizophora mucronata Rhizophora stylosa Rhizophora x lamarckii*

*Sonneratia caseolaris Sonneratia ovata Sonneratia x gulngai*

*Aegiceras floridum*

ACANTHACEAE *Acanthus ebracteatus*

BIGNONIACEAE *Dolichandrone spathacea* BOMBACACEAE *Camptostemon philippinense*

CAESALPINIACEAE *Cynometra iripa* COMBRETACEAE *Lumnitzera littorea*

EBENACEAE *Excoecaria agallocha* LYTHRACEAE *Pemphis acidula* MELIACEAE *Xylocarpus granatum*

MYRSINACEAE *Aegiceras corniculatum*

MYRTACEAE *Osbornia octodonta* PLUMBAGINACEAE *Aegialitis annulata* PTERIDACEAE *Acrostichum aureum*

RHIZOPHORACEAE *Bruguiera cylindrica*

RUBIACEAE *Scyphiphora hydrophylacea*

Table 1. List of true mangrove species in the Philippines (Spalding et al, 20101; Polidoro et al,

SONNERATIACEAE *Sonneratia alba*

STERCULIACEAE *Heritiera littoralis*

20102).

ARECACEAE *Nypa fruticans* AVICENNIACEAE *Avicennia alba*

Fig. 1. Estimated extent of mangrove areas in the Philippines from 1918 (around 450,000 hectares) to 2007 (around 289,350 hectares).


Table 2. Top 10 provinces in terms of the area with expired FLA licenses in the Philippines.

It has long been noted by various authors that most of the brackish-water ponds in the Philippines are either idle, abandoned, underutilized and in an unproductive state (Primavera and Agbayani 1997; Primavera 2000; Yap 2007; Samson and Rollon 2008; Primavera et al, 2012). There had been efforts to promote the reversion of these ponds to mangrove areas however the implementing rules and regulations had been unclear, if not nonexistent. In most cases, holders of FLA certificates are unwilling to yield the pond area for mangrove restoration (Yap, 2007; Samson and Rollon 2008). These underutilized ponds

perpetuates the loss of goods and services that mangrove areas could provide. The continued abandonment of these areas increases the vulnerability of coastal communities to the ancillary impacts of climate change such as increase in sea level (Alongi, 2002; Gilman et al, 2006; Gilman, 2008), tsunami (Alongi 2008; Dahdouh-Guebas, 2005; Vermaat & Thampanya, 2006), wave impact due to increased typhoon strength and frequency and

If massive loss of mangrove areas in the Philippines could be attributed to aquaculture development, logically therefore, restoration of idle and underproductive brackish-water ponds at least to its ecologically productive state, should be the focus of management efforts (Primavera, 2006; Samson & Rollon, 2008; Primavera & Esteban, 2008; Primavera et al, 2012). This option will greatly enhance the ecological success of current efforts by 1) promoting healthy growth patterns of planted species, and 2) stop the afforestation of adjacent habitats (i.e. seagrass bed and mudflat area, **Plate 1**). These practices are widespread in the Philippines where the growth of species in afforested sites performed dismally as compared to those planted in natural mangrove forests (Samson and Rollon, 2008; **Figure 3**). Though the revegetation of idle and unproductive ponds may present a multitude of ecological, political and institutional challenges (Primavera, 2000; Samson and Rollon, 2008) to become feasible, conscious effort to move towards this objective must be prioritized. **Table 3** lists some factors that needs to be considered before deciding the reversion of idle or disused

Plate 1. Some examples of the well-meaning planting initiatives but may be less successful in

terms of ecological restoration in Talibon, Bohol, Philippines where mangroves were

coastal erosion (UNEP-WCMC, 2006; Primavera et al 2012).

ponds to mangrove areas.

planted on seagrass and mudflat areas.

Fig. 2. Illustration of the a) historical and b) present condition and c) best management options for the mangroves and brackish-water pond areas in the Philippines.

a) **a)** 

**b)** 

Fig. 2. Illustration of the a) historical and b) present condition and c) best management

options for the mangroves and brackish-water pond areas in the Philippines.

perpetuates the loss of goods and services that mangrove areas could provide. The continued abandonment of these areas increases the vulnerability of coastal communities to the ancillary impacts of climate change such as increase in sea level (Alongi, 2002; Gilman et al, 2006; Gilman, 2008), tsunami (Alongi 2008; Dahdouh-Guebas, 2005; Vermaat & Thampanya, 2006), wave impact due to increased typhoon strength and frequency and coastal erosion (UNEP-WCMC, 2006; Primavera et al 2012).

If massive loss of mangrove areas in the Philippines could be attributed to aquaculture development, logically therefore, restoration of idle and underproductive brackish-water ponds at least to its ecologically productive state, should be the focus of management efforts (Primavera, 2006; Samson & Rollon, 2008; Primavera & Esteban, 2008; Primavera et al, 2012). This option will greatly enhance the ecological success of current efforts by 1) promoting healthy growth patterns of planted species, and 2) stop the afforestation of adjacent habitats (i.e. seagrass bed and mudflat area, **Plate 1**). These practices are widespread in the Philippines where the growth of species in afforested sites performed dismally as compared to those planted in natural mangrove forests (Samson and Rollon, 2008; **Figure 3**). Though the revegetation of idle and unproductive ponds may present a multitude of ecological, political and institutional challenges (Primavera, 2000; Samson and Rollon, 2008) to become feasible, conscious effort to move towards this objective must be prioritized. **Table 3** lists some factors that needs to be considered before deciding the reversion of idle or disused ponds to mangrove areas.

Plate 1. Some examples of the well-meaning planting initiatives but may be less successful in terms of ecological restoration in Talibon, Bohol, Philippines where mangroves were planted on seagrass and mudflat areas.

Poor productivity level due to high acidity and poor shrimp survival

Further degradation of the ecosystem – i.e. acidification, soil erosion – if some rehabilitation activity is not undertaken (Stevenson et al 1999) Arrest surface erosion and subsidence and compaction of soil profile within and in the adjacent environment (Burbridge and Hellin, 2002)

Availability of water borne seedlings and propagules from neighboring

Possibility of occurrence of natural process of secondary succession (Lewis

 **CONSIDERATIONS**  Ecological If farm was constructed in an inappropriate site such that:

Frequently hit by typhoons (Stevenson et al 1999)

Tidal hydrology can still be restored (Lewis 2005)

Social Willingness and cooperation of stakeholders (Stevenson et al 1999)

Economic Non – sustainable and unproductive pond operation (Stevenson et al 1999)

revegetation efforts (Stevenson et al 1999; Primavera 2000)

Table 3. Factors to consider before deciding the reversion of idle or underproductive ponds

The issues surrounding the decline of mangrove areas in the Philippines and the proliferation of idle and underutilized brackish-water ponds in terms of area covered are inextricably linked and may be addressed in a more integrated and adaptive approach (**Figure 4**). **Figure 2c** illustrates what may be the best management options for mangroves and brackish-water ponds in the Philippines. As cited by Primavera and Esteban (2008), Saenger et al (1986) recommended the 4:1 mangrove to pond ratio to sustain the ecological function of the mangrove ecosystem. However this recommendation poses a great challenge to the Philippine government as the basic information on the present state of ownership and

If degradation not arrested, repair may become progressively more expensive and difficult – rehabilitation costs would be balanced by costs

Provide additional protection from strong waves; if infrastructures for protection against strong waves and typhoons are more costly than

Maintenance of mangrove greenbelt as required by law – Fishery Reform

mangrove communities (Lewis 2005)

avoided (Stevenson et al 1999)

Code (Primavera, 1995)

operation of these brackish-water ponds are lacking.

Existing comprehensive land – use plan

Farm density is already too high

There is insufficient water supply Too much rainfall; Unsuitable soils

Occurrence of diseases

(Stevenson et al 1999)

2005)

Institutional Expired FLAs

to mangrove areas.

Fig. 3. A comparison of the internodal growth patterns of *Rhizophora stylosa* planted in different mangrove planting sites in Talibon, Bohol, Philippines: a) Cataban Island and b) Barangay San Francisco.

Inside mangrove forest

3.34 + 0.76

**a)** 

1.70 + 0.47

On seagrass bed

AM J J A SOND J FMAM J J A SOND J FMAM J J A SOND J JMMAM J J A SOND J FMAM J J A SOND J FMAM J J A SOND J FMAM J J A SOND J FMAM J J A SOND J FMAM J J A SOOND J FMAM J J A SON

**Approximate time, April 2001 to December 2010**

Old plantation On mudflat

3.42 + 0.89 2.31 + 0.52

**b)** 

Fig. 3. A comparison of the internodal growth patterns of *Rhizophora stylosa* planted in different mangrove planting sites in Talibon, Bohol, Philippines: a) Cataban Island and b)

MAM J J A SOND J FMAM J J A SOND J FMAM J J A SOND J FMAM J J A SOND J FMAM J J A SOND J FMAM J J A SON

**Approximate time, March 2005 to November 2010**

Barangay San Francisco.

0

1

2

3

4

**Internodal length, cm**

5

6

7

**0**

**1**

**2**

**3**

**4**

**Internodal length, cm**

**5**

**6**

**7**

**8**


Table 3. Factors to consider before deciding the reversion of idle or underproductive ponds to mangrove areas.

The issues surrounding the decline of mangrove areas in the Philippines and the proliferation of idle and underutilized brackish-water ponds in terms of area covered are inextricably linked and may be addressed in a more integrated and adaptive approach (**Figure 4**). **Figure 2c** illustrates what may be the best management options for mangroves and brackish-water ponds in the Philippines. As cited by Primavera and Esteban (2008), Saenger et al (1986) recommended the 4:1 mangrove to pond ratio to sustain the ecological function of the mangrove ecosystem. However this recommendation poses a great challenge to the Philippine government as the basic information on the present state of ownership and operation of these brackish-water ponds are lacking.

Table 4. Estimated mangrove extent, brackish-water pond area and mangrove to pond ratio

Table 5. The estimated brackish-water pond area, ponds with and not covered by FLA as of 2010 in the top 10 provinces with the largest hectarage of brackish-water ponds in the

 **(ha) (ha, 2010)**  Batangas Calatagan 299.43 111.21 Lian 78.64 6.60 Quezon Calauag 533.76 479.75 Sorsogon Sorsogon City 318.81 137.06 Prieto Diaz 463.48 299.40 Iloilo Iloilo City 871.92 2.54 Former Zamboanga del Sur Aurora 3,955.86 524.53 Kabasalan 992.82 588.33 Table 6. Mangrove extent, brackish-water pond and FLA areas in selected sites of the

**PROVINCE MUNICIPALITY POND AREA FLA AREA** 

in the top 10 provinces with the largest hectarage of brackish-water ponds in the

Philippines.

Philippines.

Philippines.

Fig. 4. DPSIR model on the state of mangrove forests and brackish-water ponds in the Philippines.

#### **2. Mangrove-pond ratio of selected aquaculture production centers in the Philippines**

As presented in the previous section, brackish-water ponds now occupy a large part of the natural mangrove areas in the Philippines. In the provinces with the largest area of brackishwater ponds in the Philippines, mangrove loss is more than 75% of the natural forest. The mangrove-pond ratio in these areas ranges from 1:2 to 1:1,586 (**Table 4**). However 44 to 99% percent of these brackish-water pond areas are not covered by FLA (**Table 5). Figure 5** presents the potential mangrove extent and hectarage of brackish-water pond area, with or without FLA in selected sites of the country. On the average, around 50% of the historical mangrove areas in these selected sites were converted to brackish-water ponds with Iloilo City having the highest percentage of converted area (90%). However, as in the situation in many provinces around the country, not all of the brackish-water ponds have FLAs, on the average only 40% are under the 25-years lease agreement with the government (**Table 6**). Worse, only 60% of these FLAs are still active. What could have happened to the other mangrove areas that were converted to brackish-water ponds? One possible answer to this is that the other areas have land titles or undocumented as in the case of the 72 has (92%) of ponds in Lian, Batangas.

38 Aquaculture and the Environment - A Shared Destiny

PRESSURE

STATE

• Idle and underutilized brackish-water ponds • Titled and undocumented ponds

34

• > 50% denuded mangrove areas • 93,785 ha of mangrove still categorized as alienable and disposable • Afforested mudflat and seagrass beds

• Absence of an efficient and effective national program on mangrove and brackishwater pond management • Continued exploitation for wood products • Ineffective enforcement

DRIVING FORCE • Aquaculture production • Coastal developments • Human settlements

IMPACT

• Loss of mangroves ecological and economic goods and services • Low production from aquaculture ponds

Fig. 4. DPSIR model on the state of mangrove forests and brackish-water ponds in the

**2. Mangrove-pond ratio of selected aquaculture production centers in the** 

As presented in the previous section, brackish-water ponds now occupy a large part of the natural mangrove areas in the Philippines. In the provinces with the largest area of brackishwater ponds in the Philippines, mangrove loss is more than 75% of the natural forest. The mangrove-pond ratio in these areas ranges from 1:2 to 1:1,586 (**Table 4**). However 44 to 99% percent of these brackish-water pond areas are not covered by FLA (**Table 5). Figure 5** presents the potential mangrove extent and hectarage of brackish-water pond area, with or without FLA in selected sites of the country. On the average, around 50% of the historical mangrove areas in these selected sites were converted to brackish-water ponds with Iloilo City having the highest percentage of converted area (90%). However, as in the situation in many provinces around the country, not all of the brackish-water ponds have FLAs, on the average only 40% are under the 25-years lease agreement with the government (**Table 6**). Worse, only 60% of these FLAs are still active. What could have happened to the other mangrove areas that were converted to brackish-water ponds? One possible answer to this is that the other areas have land titles or undocumented as in the case of the 72 has (92%) of

Philippines.

RESPONSE • Mapping and

A and D • Conduct of bioeconomic assessment of present mangrove and brackish-water pond areas • Drafting of national mangrove and brackish-water management plan with institutionalized monitoring and incentive system • Climate-smart

inventory of mangrove and brackish-water pond areas • Reclassification of mangrove areas under

reforestation activities • Optimize fish yield and reduce pond size to as small as possible • Aquasilviculture

**Philippines** 

ponds in Lian, Batangas.


Table 4. Estimated mangrove extent, brackish-water pond area and mangrove to pond ratio in the top 10 provinces with the largest hectarage of brackish-water ponds in the Philippines.


Table 5. The estimated brackish-water pond area, ponds with and not covered by FLA as of 2010 in the top 10 provinces with the largest hectarage of brackish-water ponds in the Philippines.


Table 6. Mangrove extent, brackish-water pond and FLA areas in selected sites of the Philippines.

The contribution of the aquaculture sector is still the highest (from 38 to 49%) in terms of the volume of production in the last decade (**Figure 6**). Almost fifty percent of the total fisheries production in 2010 comes from this sector. Brackish-water pond aquaculture is still the subsector with the highest percentage of production in terms of volume (**Figure 7**). However

Fig. 6. Percent contribution of the different sectors of fisheries production in the Philippines

Commercial Fisheries Municipal Fisheries Aquaculture

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

Fig. 7. Percent contribution of the different subsectors of aquaculture production in the

Brackishwater pond Freshwater fishpond

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

Seaweed culture Other culture type and environment

**3. Pond area-fish yield in the past decade** 

from 2001 to 2010.

0%

10%

20%

30%

**Percent contribution of the different sectors** 

40%

50%

60%

Philippines from 2001 to 2010.

0%

10%

20%

30%

40%

**Percent contribution of major subsectors**

50%

60%

70%

80%

Fig. 5. Digitized Google Earth images of potential mangrove (green) and brackish-water ponds areas (dark yellow) in selected sites of the Philippines, a) Calatagan and b) Lian, Batangas, c) Calauag, Quezon, d) Sorsogon City, e) Prieto Diaz, Sorsogon, f) Iloilo City, g) Aurora, Zamboanga del Sur, and h) Kabasalan, Zamboanga Sibugay.

#### **3. Pond area-fish yield in the past decade**

40 Aquaculture and the Environment - A Shared Destiny

**a b**

**c d**

**e f** 

**g h**

Fig. 5. Digitized Google Earth images of potential mangrove (green) and brackish-water ponds areas (dark yellow) in selected sites of the Philippines, a) Calatagan and b) Lian, Batangas, c) Calauag, Quezon, d) Sorsogon City, e) Prieto Diaz, Sorsogon, f) Iloilo City, g)

Aurora, Zamboanga del Sur, and h) Kabasalan, Zamboanga Sibugay.

The contribution of the aquaculture sector is still the highest (from 38 to 49%) in terms of the volume of production in the last decade (**Figure 6**). Almost fifty percent of the total fisheries production in 2010 comes from this sector. Brackish-water pond aquaculture is still the subsector with the highest percentage of production in terms of volume (**Figure 7**). However

Fig. 6. Percent contribution of the different sectors of fisheries production in the Philippines from 2001 to 2010.

Fig. 7. Percent contribution of the different subsectors of aquaculture production in the Philippines from 2001 to 2010.

The present paper is an attempt to extend the options presented by Samson and Rollon (2008) to include brackish-water ponds covered by land titles and those that are

**PONDS WITH LEGAL INSTRUMENTS PONDS WITHOUT** 

1. Aquasilviculture (Primavera, 2000) 2. Optimize fish yield and reduce pond size to as small as possible (Samson and Rollon, 2008); revert unutilized areas to mangrove forest

Table 8. List of management options for brackish-water ponds with and without legal

**4.1 For ponds with active FLAs and the overall fish yield is optimal, apply semi-**

**intensive aquaculture (modified from Samson and Rollon, 2008)** 

A total of six rational management strategies are being proposed for the utilization of brackish-water ponds in the Philippines. The options are specific for the current state of

For ponds with existing FLA, the most rational objective of management will be semiintensive aquaculture production to optimize the use of leased areas (Janssen and Padilla, 1999). In 2007, there were around 59, 923 hectares of potential brackish-water ponds listed in the website of the Bureau of Fisheries and Aquatic Resources. However, a closer look at the list revealed that only 44% of these have active FLAs, the rest of the lease are expired. This option may be of importance to the provinces of Quezon, Zamboanga del Sur, Iloilo, Occidental Mindoro, Negros Occidental, Samar, Masbate, Bohol, Zamboanga City and Capiz where brackish-water pond areas with FLAs are relatively extensive. Applying this intervention may yield a net income of US\$680 million (at US\$1 = Php 42.61) conservatively

**EXISTING LEGAL INSTRUMENT OF OWNERSHIP** 

1. If pond existence is necessary based on bioeconomic analysis, reapply FLA and optimize fish yield (Samson and Rollon,

2. Revert to mangrove

revegetation b. Assisted planting

2008).

areas: a. Natural

undocumented (**Table 8**).

1. For ponds with active FLAs and the overall fish yield is optimal, apply semi-intensive aquaculture. (modified from Samson and Rollon, 2008). 2. Optimize fish yield and reduce pond size to as small as possible (Samson and Rollon, 2008). Follow the 4:1 mangrove-pond area ratio to maintain ecological health (as cited in Primavera,

2000).

in 10 years.

ownership of the ponds.

With active FLA Titled ponds

instruments (with FLA, land titles) in the Philippines.

a steady decline of production from this sector is apparent from 2001 to 2010 and this may be due to the under productivity of almost 40% of brackish-water ponds in the country. Included in these areas are three of the provinces with the largest hectarage of brackishwater ponds, namely former Zamboanga del Sur, Bulacan and Aklan (**Table 7**).


Table 7. Volume of total aquaculture and brackish-water pond production in the top 10 provinces with the largest hectarage of brackish-water ponds in the Philippines.

In terms of the physical area utilized, brackish-water aquaculture is the biggest sub-sector in Philippine aquaculture (Cruz, 1997), however, its contribution to total fisheries production may not be proportionate with its physical magnitude in terms of area covered (~169,000 ha in 1995, Yap, 2007).

#### **4. Management options for brackish-water pond areas in the Philippines**

Brackish-water ponds in the Philippines may be classified into two: 1) those with valid legal instrument of ownership and operation, 2) those that do not have legal instrument of operation and undocumented. The first classification are of two types, those with FLAs and those with land titles. As presented in the previous section, 40 to 50% of these ponds, are now left idle or underproductive. A number of authors discussed several management strategies to address this problem (Primavera, 2000, 2006; Yap, 2007; Samson and Rollon, 2008; Primavera and Esteban, 2008; Primavera et al, 2012). Samson and Rollon in 2008 proposed a possible decision tree of options for idle and active brackish-water ponds in the Philippines. These options are specifically for those with FLAs.

a steady decline of production from this sector is apparent from 2001 to 2010 and this may be due to the under productivity of almost 40% of brackish-water ponds in the country. Included in these areas are three of the provinces with the largest hectarage of brackish-

water ponds, namely former Zamboanga del Sur, Bulacan and Aklan (**Table 7**).

Table 7. Volume of total aquaculture and brackish-water pond production in the top 10 provinces with the largest hectarage of brackish-water ponds in the Philippines.

**4. Management options for brackish-water pond areas in the Philippines** 

Philippines. These options are specifically for those with FLAs.

in 1995, Yap, 2007).

In terms of the physical area utilized, brackish-water aquaculture is the biggest sub-sector in Philippine aquaculture (Cruz, 1997), however, its contribution to total fisheries production may not be proportionate with its physical magnitude in terms of area covered (~169,000 ha

Brackish-water ponds in the Philippines may be classified into two: 1) those with valid legal instrument of ownership and operation, 2) those that do not have legal instrument of operation and undocumented. The first classification are of two types, those with FLAs and those with land titles. As presented in the previous section, 40 to 50% of these ponds, are now left idle or underproductive. A number of authors discussed several management strategies to address this problem (Primavera, 2000, 2006; Yap, 2007; Samson and Rollon, 2008; Primavera and Esteban, 2008; Primavera et al, 2012). Samson and Rollon in 2008 proposed a possible decision tree of options for idle and active brackish-water ponds in the The present paper is an attempt to extend the options presented by Samson and Rollon (2008) to include brackish-water ponds covered by land titles and those that are undocumented (**Table 8**).


Table 8. List of management options for brackish-water ponds with and without legal instruments (with FLA, land titles) in the Philippines.

A total of six rational management strategies are being proposed for the utilization of brackish-water ponds in the Philippines. The options are specific for the current state of ownership of the ponds.

#### **4.1 For ponds with active FLAs and the overall fish yield is optimal, apply semiintensive aquaculture (modified from Samson and Rollon, 2008)**

For ponds with existing FLA, the most rational objective of management will be semiintensive aquaculture production to optimize the use of leased areas (Janssen and Padilla, 1999). In 2007, there were around 59, 923 hectares of potential brackish-water ponds listed in the website of the Bureau of Fisheries and Aquatic Resources. However, a closer look at the list revealed that only 44% of these have active FLAs, the rest of the lease are expired. This option may be of importance to the provinces of Quezon, Zamboanga del Sur, Iloilo, Occidental Mindoro, Negros Occidental, Samar, Masbate, Bohol, Zamboanga City and Capiz where brackish-water pond areas with FLAs are relatively extensive. Applying this intervention may yield a net income of US\$680 million (at US\$1 = Php 42.61) conservatively in 10 years.

As mentioned earlier, under productivity of the pond may be brought about by the inappropriateness of the site for fish production (Stevenson et al, 1999). Problems such as the lack of supply of water and sedimentation may cause fish production to go down to unsustainable level. If this is the case, the site can be properly assessed for reversion to its original habitat. Natural revegetation will require much less labor and financial output as compared to assisted planting, however, there are cases when the site's modification will not anymore allow the recruitment and settlement of mangrove propagules in the area. As of 2007, there are around 39t hectares of brackish-water ponds with expired FLAs. Revegetating these ponds will greatly increase the percentage of rehabilitation efforts in the Philippines. Provinces with 85 to 100% of expired FLAs are Antique, Maguindanao, Lanao del Norte, Palawan, Basilan, Sulu, Davao Oriental, Sultan Kudarat, Northern Samar and

Primavera in 2000 estimated that there are around 230t hectares of mangroves which had been converted to brackish-water ponds, using this number and subtracting the areas listed with FLA (59, 293), it will give us an estimate of around 74% (170,707 hectares) brackishwater ponds which are titled or undocumented. For these titled ponds, the management strategies will not be straightforward as the utilization of titled ponds rely greatly on its owners. The most rational option for these active title ponds is to sustainably operate the ponds to maximize the production potential of the area. Incentive mechanisms may be institutionalized to encourage titled pond owners to apply the two options most especially if these ponds are idle. These may be in the form of tax incentives and awards for sustainable operation, technical assistance to optimize production, and provision of seedlings for revegetation and others. One of the strategies that may benefit both the pond operators and government will be aqua-silviculture (Melana et al 2000a & b). Aquasilviculture promotes the mix of sustainable pond operation and the revegetation of some parts of the brackishwater ponds (Melana et al 2000a & b). Although this culture practice has been and are being practiced in some parts of the country (i.e. Aklan; Quezon), its ecological and economic

**4.6 For idle titled ponds, fish yield may be optimized but pond size as in option 2 may be reduced to as small as possible and revert unutilized areas to mangrove forest** 

The option of revegetating idle ponds will greatly benefit pond operators and coastal communities as this may bring back mangrove goods and services and may potentially be a supplemental source of livelihood. One of the important mangrove services that the pond operators may consider is coastal protection. In the light of the looming impacts of climate change, mangroves will play a pivotal role in mitigating tsunami, strong waves and coastal erosion (Alongi, 2002, 2008; Dahdouh-Geubas et al, 2005; Gilman, 2006, 2008; Mc Leod &

Proper accounting and management of all brackish-water ponds in the country should be a top priority. A comprehensive and proper accounting of these titled ponds may help the

**4.4 For ponds with expired FLAs and production is suboptimal and not necessary, revert to mangrove areas thru natural revegetation or assisted planting (Samson and** 

**Rollon, 2008)** 

Camarines Sur.

**4.5 For active titled ponds, apply aqua-silviculture** 

benefits are not yet fully realized.

Salm, 2006; UNEP-WCMC, 2006).

#### **4.2 For ponds with active FLAs and the fish yield is not anymore financially sustainable, production needs to be optimized and pond size may be reduced to as small as possible whereby a 4:1 mangrove-pond area ratio may be followed to restore and maintain the ecological health of the system (Primavera, 2000; Samson and Rollon, 2008; Primavera and Esteban, 2008)**

This option particularly addresses brackish-water ponds with FLAs but are not operating sustainably. Technical assistance from concerned agencies (i.e. BFAR) must be sought to optimize the production of these ponds. However, it may also be that the reason for the under productivity of these ponds is that the area may not anymore be suitable for production hence the strategy on reducing the pond size and following the 4:1 mangrovepond area ratio is being put forward (Primavera, 2006). This option on the reversion of some ponds with existing FLA to mangroves will require joint efforts from concerned agencies (i.e. Department of Environment and Natural Resources (DENR), BFAR, Department of Interior and Local Government (DILG)) and the institutionalization of strategies on how the pond operators will be convinced to reforest their underutilized ponds. Strategies may be in the form of incentives like granting of awards for operators with the most environment friendly operations. Another strategy may be is to highlight the importance of these reverted areas in bringing back mangrove goods and services which may become a sustainable source of income in the form of mangrove associated fisheries. The role of these former mangrove areas in mitigating the impacts of climate change such as sea level rise and increased storminess may also convince pond owners to reforest their idle and unproductive ponds. A more political-institutional approach will be to strengthen the monitoring of pond operations such that the 5 years limit for unproductive ponds will be imposed and those ponds will be reverted back to DENR. For the government, specifically BFAR, this is an opportunity to improve its system of monitoring and evaluation of existing FLAs in order to sustainably maximize the potential yield of these leased areas. Conservatively if strategically implemented, this option may yield a net income of US\$657 million in 10 years.

#### **4.3 For ponds with expired FLAs and the pond existence is necessary based on bioeconomic analysis, reapply FLA and optimize fish yield (Samson and Rollon, 2008)**

For brackish-water ponds with expired FLAs, the management strategy will require a balance between the importance of the pond area for fish production and the importance of these areas in restoring its natural ecological health and function (Janssen and Padilla, 1999; Barbier, 2000). The importance of the pond for fish production should not only be assessed in terms of what the operators can gain from it but also if its needed in a broader context of fish production in an area. For example, if an area is a major source of fisheries products and the non-operation of some ponds will cause a disruption on the supply, then production must be sustainably optimized to meet the target volume. This kind of assessment must be included in the procedures being followed by BFAR before renewing the lease agreement of expired FLAs. A more rigorous evaluation of the production efficiency of the pond must be developed to ensure the optimal use of the leased area. Pond operators must be required to submit a regular report of their production, as well as their income during the period when the lease agreement is in effect. This report must first be reviewed by BFAR before granting renewal.

**sustainable, production needs to be optimized and pond size may be reduced to as small as possible whereby a 4:1 mangrove-pond area ratio may be followed to restore and maintain the ecological health of the system (Primavera, 2000; Samson and** 

This option particularly addresses brackish-water ponds with FLAs but are not operating sustainably. Technical assistance from concerned agencies (i.e. BFAR) must be sought to optimize the production of these ponds. However, it may also be that the reason for the under productivity of these ponds is that the area may not anymore be suitable for production hence the strategy on reducing the pond size and following the 4:1 mangrovepond area ratio is being put forward (Primavera, 2006). This option on the reversion of some ponds with existing FLA to mangroves will require joint efforts from concerned agencies (i.e. Department of Environment and Natural Resources (DENR), BFAR, Department of Interior and Local Government (DILG)) and the institutionalization of strategies on how the pond operators will be convinced to reforest their underutilized ponds. Strategies may be in the form of incentives like granting of awards for operators with the most environment friendly operations. Another strategy may be is to highlight the importance of these reverted areas in bringing back mangrove goods and services which may become a sustainable source of income in the form of mangrove associated fisheries. The role of these former mangrove areas in mitigating the impacts of climate change such as sea level rise and increased storminess may also convince pond owners to reforest their idle and unproductive ponds. A more political-institutional approach will be to strengthen the monitoring of pond operations such that the 5 years limit for unproductive ponds will be imposed and those ponds will be reverted back to DENR. For the government, specifically BFAR, this is an opportunity to improve its system of monitoring and evaluation of existing FLAs in order to sustainably maximize the potential yield of these leased areas. Conservatively if strategically implemented, this

**4.2 For ponds with active FLAs and the fish yield is not anymore financially** 

**Rollon, 2008; Primavera and Esteban, 2008)** 

option may yield a net income of US\$657 million in 10 years.

renewal.

**4.3 For ponds with expired FLAs and the pond existence is necessary based on bioeconomic analysis, reapply FLA and optimize fish yield (Samson and Rollon, 2008)**  For brackish-water ponds with expired FLAs, the management strategy will require a balance between the importance of the pond area for fish production and the importance of these areas in restoring its natural ecological health and function (Janssen and Padilla, 1999; Barbier, 2000). The importance of the pond for fish production should not only be assessed in terms of what the operators can gain from it but also if its needed in a broader context of fish production in an area. For example, if an area is a major source of fisheries products and the non-operation of some ponds will cause a disruption on the supply, then production must be sustainably optimized to meet the target volume. This kind of assessment must be included in the procedures being followed by BFAR before renewing the lease agreement of expired FLAs. A more rigorous evaluation of the production efficiency of the pond must be developed to ensure the optimal use of the leased area. Pond operators must be required to submit a regular report of their production, as well as their income during the period when the lease agreement is in effect. This report must first be reviewed by BFAR before granting

#### **4.4 For ponds with expired FLAs and production is suboptimal and not necessary, revert to mangrove areas thru natural revegetation or assisted planting (Samson and Rollon, 2008)**

As mentioned earlier, under productivity of the pond may be brought about by the inappropriateness of the site for fish production (Stevenson et al, 1999). Problems such as the lack of supply of water and sedimentation may cause fish production to go down to unsustainable level. If this is the case, the site can be properly assessed for reversion to its original habitat. Natural revegetation will require much less labor and financial output as compared to assisted planting, however, there are cases when the site's modification will not anymore allow the recruitment and settlement of mangrove propagules in the area. As of 2007, there are around 39t hectares of brackish-water ponds with expired FLAs. Revegetating these ponds will greatly increase the percentage of rehabilitation efforts in the Philippines. Provinces with 85 to 100% of expired FLAs are Antique, Maguindanao, Lanao del Norte, Palawan, Basilan, Sulu, Davao Oriental, Sultan Kudarat, Northern Samar and Camarines Sur.

#### **4.5 For active titled ponds, apply aqua-silviculture**

Primavera in 2000 estimated that there are around 230t hectares of mangroves which had been converted to brackish-water ponds, using this number and subtracting the areas listed with FLA (59, 293), it will give us an estimate of around 74% (170,707 hectares) brackishwater ponds which are titled or undocumented. For these titled ponds, the management strategies will not be straightforward as the utilization of titled ponds rely greatly on its owners. The most rational option for these active title ponds is to sustainably operate the ponds to maximize the production potential of the area. Incentive mechanisms may be institutionalized to encourage titled pond owners to apply the two options most especially if these ponds are idle. These may be in the form of tax incentives and awards for sustainable operation, technical assistance to optimize production, and provision of seedlings for revegetation and others. One of the strategies that may benefit both the pond operators and government will be aqua-silviculture (Melana et al 2000a & b). Aquasilviculture promotes the mix of sustainable pond operation and the revegetation of some parts of the brackishwater ponds (Melana et al 2000a & b). Although this culture practice has been and are being practiced in some parts of the country (i.e. Aklan; Quezon), its ecological and economic benefits are not yet fully realized.

#### **4.6 For idle titled ponds, fish yield may be optimized but pond size as in option 2 may be reduced to as small as possible and revert unutilized areas to mangrove forest**

The option of revegetating idle ponds will greatly benefit pond operators and coastal communities as this may bring back mangrove goods and services and may potentially be a supplemental source of livelihood. One of the important mangrove services that the pond operators may consider is coastal protection. In the light of the looming impacts of climate change, mangroves will play a pivotal role in mitigating tsunami, strong waves and coastal erosion (Alongi, 2002, 2008; Dahdouh-Geubas et al, 2005; Gilman, 2006, 2008; Mc Leod & Salm, 2006; UNEP-WCMC, 2006).

Proper accounting and management of all brackish-water ponds in the country should be a top priority. A comprehensive and proper accounting of these titled ponds may help the

of sediments (Krauss, 2008). As had been observed in other areas where tidal gates were destroyed, the pond elevation after some time levels with the adjacent mangrove forest, on the average this may take 1 to 2 years. This could then be followed by an observation period of where the seedlings will settle to determine if proper spacing of the seedlings to favor growth will be achieved. Natural recruitment of propagules in the pond site may not be a problem due to the abundance of seedlings near tidal gates as was observed in the study site in Lian, Batangas, (**Figure 9**). Assisted planting may be considered by replanting the propagules in the areas of the pond where elevation is relatively higher. Lewis (2005, 2009) in collaboration with various authors (1997, 2000) discussed in details the necessary steps for successful management and rehabilitation of abandoned or disused brackish-water ponds.

Fig. 9. Abundance of seedlings of *Avicennia marina* and *Rhizophora stylosa* from the seafront

The inverse link between the remaining mangrove areas and existing brackish-water ponds in the Philippines had been well recognized for three decades now. The degraded state of mangrove areas is caused by its continued overexploitation for wood products, unregulated conversion for coastal development, inappropriate planting programs, and more importantly the absence or lack of more efficient and adaptive rehabilitation and conservation strategies. The proliferation of idle and underutilized brackish-water ponds is also an effect of the absence of efficient monitoring and evaluation system for the condition and status of these ponds. Laws and administrative orders for the rehabilitation and protection of mangroves areas as well as the responsible utilization of brackish-water ponds in the Philippines are in place, however, the implementing rules and regulations for these policies seemed to be lacking in coverage and effectivity. At present there are approximately 232,100 ha of brackish-water ponds, however only 59,923 ha have lease agreements from the Bureau of Fisheries and Aquatic Resources. At present, sixty-six percent of these FLAs are already expired. The remaining mangrove areas which were reportedly converted to

area of a mangrove forest to the gate of a brackish-water pond in Lian, Batangas,

Philippines.

**6. Conclusions** 

Philippine government formulate policies that will encourage environmentally sustainable fish production and resolve the fisheries and forestry utilization conflict in our mangrove areas.

Using available literature on the direct and indirect uses of mangroves (White & Cruz-Trinidad, 1998; Samonte-Tan & Armedilla, 2004; Walton, 2006), the TEV of the different options were estimated. Of the six management options that were proposed, the option that involves the reforestation of idle and unproductive ponds and the practice of aquasilviculture may bring about the highest total economic value at US\$ 4.28 billion (at US\$1 = Php 42.61) in 10 years. These two options provide opportunities to sustainably maximize the aquaculture potential and the variety of mangroves goods and services that this ecosystem could offer. In the aquasilviculture option, the economic goods will not only come from fish production from the pond itself but also to the recruitment and settlement of mangrove associated fish and organisms. The ecotourism potential of the system and its coastal protection value may also be restored thereby increasing the total economic value of the system.

#### **5. Topographic/ hydrological conditions of these 'excess' areas in selected areas of the Philippines**

What may pose a problem in the natural revegetation of the target pond site is its mean sea level elevation relative to the mean sea level elevation of the adjacent mangrove area (**Figure 8**). A study site in Lian, Batangas revealed that the pond site is 1 meter lower than that of the adjacent mangrove area. However this may not pose a serious problem for natural revegetation. Perhaps a natural in-filling by erosion should be allowed for some time, and elevation monitored. The first necessary step in the revegetation of the pond will be the opening of the tidal gates to allow for natural in-filling of sediment. This would also allow the recruitment and settlement of propagules however during the first months of revegetation, seedlings may not grow as they may either drown or get buried by inflowing

Fig. 8. Elevation map of the mangrove and pond site relative to mean low tide level at the study site in Lian, Batangas, Philippines.

of sediments (Krauss, 2008). As had been observed in other areas where tidal gates were destroyed, the pond elevation after some time levels with the adjacent mangrove forest, on the average this may take 1 to 2 years. This could then be followed by an observation period of where the seedlings will settle to determine if proper spacing of the seedlings to favor growth will be achieved. Natural recruitment of propagules in the pond site may not be a problem due to the abundance of seedlings near tidal gates as was observed in the study site in Lian, Batangas, (**Figure 9**). Assisted planting may be considered by replanting the propagules in the areas of the pond where elevation is relatively higher. Lewis (2005, 2009) in collaboration with various authors (1997, 2000) discussed in details the necessary steps for successful management and rehabilitation of abandoned or disused brackish-water ponds.

Fig. 9. Abundance of seedlings of *Avicennia marina* and *Rhizophora stylosa* from the seafront area of a mangrove forest to the gate of a brackish-water pond in Lian, Batangas, Philippines.

#### **6. Conclusions**

46 Aquaculture and the Environment - A Shared Destiny

Philippine government formulate policies that will encourage environmentally sustainable fish production and resolve the fisheries and forestry utilization conflict in our mangrove

Using available literature on the direct and indirect uses of mangroves (White & Cruz-Trinidad, 1998; Samonte-Tan & Armedilla, 2004; Walton, 2006), the TEV of the different options were estimated. Of the six management options that were proposed, the option that involves the reforestation of idle and unproductive ponds and the practice of aquasilviculture may bring about the highest total economic value at US\$ 4.28 billion (at US\$1 = Php 42.61) in 10 years. These two options provide opportunities to sustainably maximize the aquaculture potential and the variety of mangroves goods and services that this ecosystem could offer. In the aquasilviculture option, the economic goods will not only come from fish production from the pond itself but also to the recruitment and settlement of mangrove associated fish and organisms. The ecotourism potential of the system and its coastal protection value may also be restored thereby increasing the total economic value of

**5. Topographic/ hydrological conditions of these 'excess' areas in selected** 

Fig. 8. Elevation map of the mangrove and pond site relative to mean low tide level at the

What may pose a problem in the natural revegetation of the target pond site is its mean sea level elevation relative to the mean sea level elevation of the adjacent mangrove area (**Figure 8**). A study site in Lian, Batangas revealed that the pond site is 1 meter lower than that of the adjacent mangrove area. However this may not pose a serious problem for natural revegetation. Perhaps a natural in-filling by erosion should be allowed for some time, and elevation monitored. The first necessary step in the revegetation of the pond will be the opening of the tidal gates to allow for natural in-filling of sediment. This would also allow the recruitment and settlement of propagules however during the first months of revegetation, seedlings may not grow as they may either drown or get buried by inflowing

areas.

the system.

**areas of the Philippines** 

study site in Lian, Batangas, Philippines.

The inverse link between the remaining mangrove areas and existing brackish-water ponds in the Philippines had been well recognized for three decades now. The degraded state of mangrove areas is caused by its continued overexploitation for wood products, unregulated conversion for coastal development, inappropriate planting programs, and more importantly the absence or lack of more efficient and adaptive rehabilitation and conservation strategies. The proliferation of idle and underutilized brackish-water ponds is also an effect of the absence of efficient monitoring and evaluation system for the condition and status of these ponds. Laws and administrative orders for the rehabilitation and protection of mangroves areas as well as the responsible utilization of brackish-water ponds in the Philippines are in place, however, the implementing rules and regulations for these policies seemed to be lacking in coverage and effectivity. At present there are approximately 232,100 ha of brackish-water ponds, however only 59,923 ha have lease agreements from the Bureau of Fisheries and Aquatic Resources. At present, sixty-six percent of these FLAs are already expired. The remaining mangrove areas which were reportedly converted to

Department of Environment and Natural Resources – National Mapping and Resource

Duke, N.C., Ball, M.C. & Ellison, J.C. (1998). Factors influencing biodiversity and distributional gradients in mangroves. *Global Ecology and Biogeography Letters* 7(1): 27-47. Food and Agriculture Organization (FAO). (2003). Status and trends in mangrove area

Field, C.D. (1998). Rehabilitation of mangrove ecosystems: an overview. *Marine Pollution* 

Gilman, E., et al. (2006). Pacific Island Mangroves in a Changing Climate and Rising Sea.

Gilman, E. L. (2008). Threats to mangroves from climate change and adaptation options.

Janssen, R., & Padilla, J.E. (1999). Preservation or Conversion? Valuation and evaluation of a

Krauss, K.W., et al. (2008). Environmental drivers in mangrove establishment and and early development: a review. *Aquatic Botany*, doi: 10.1016/j.aquabot.2007.12.014. Lewis, R.R. III, Erftemeijer, P.L.A., & Sayaka, A. (2000). Mangrove rehabilitation after

Lewis, R. R., & Marshall, M. J. (1997). Principles of successful rehabilitation of shrimp

Lewis, R.R. (2009). Methods and criteria for successful mangrove forest rehabilitation. In:

McLeod,E., & Salm, R.V. (2006). Managing Mangroves for Resilience to Climate Change.

Melana, D.M., Melana, E.E., & Mapalo, A.M. (2000a). Mangrove Management and

Melana, D.M., et al. (2000b). Mangrove Management Handbook. Department of

Polidoro, B.A. et al. (2010). The Loss of Species: Mangrove Extinction Risk and Geographic Areas of Global Concern. *PLoS ONE* 5(4): e10095. doi:10.1371/journal.pone.0010095. Primavera, J.H. (1991). Intensive prawn farming in the Philippines: ecological, social, and

September 15/20, Palacio de Convenciones de La Habana, Cuba, 126pp. Lewis, Roy R. (2005). Ecological engineering for successful management and rehabilitation

FAO. (2007). The world's mangroves, 1980-2005. FAO For. Pap. 153, 77 p.

Programme, Regional Seas Programme, Nairobi, KENYA.

*Aquatic Botany* (2008), doi:10.1016/j.aquabot.2007.12.009

Aquaculture, World Bank and NACA, Bangkok, Thailand.

of mangrove forests. *Ecological Engineering* 24: 403 – 418.

*An Integrated ecosystem approach*. Elsevier, pp 787-800.

Resource Management Project, Cebu, Philippines, 96 p.

economic implications. *Ambio* 20 (1): 28-33.

IUCN, Gland, Switzerland. 64pp.

Thailand.

unpublished.

*Bulletin* 37(8): 383-392.

Information Authority (DENR-NAMRIA). (2007). Regional Mangrove Statistics,

extent worldwide. By Wilkie, M.L. and Fortuna, S. Forest Resources Assessment Working Paper No. 63. Forest Resources Division. FAO, Rome. (Unpublished)

UNEP Regional Seas Reports and Studies No. 179. United Nations Environment

mangrove forest in the Philippines. *Environmental and Resource Economics* 14: 297-331.

shrimp aquaculture: A case study in progress at the Don Sak National Forest Reserve. Southern Thailand. Thematic Review of Coastal Wetlands and

aquaculture ponds back to mangrove forests. Programa/resumes de Marcuba '97,

Perillo, G.E., Wolanski, E., Cahoon, D.R., Brinson, M.M. (Eds), Coastal Wetlands:

Development in the Philippines. Oral presentation at *Mangrove and aquaculture management*, 14 – 16 February, 2000, Kasetsart University Campus, Bangkok,

Environment and Natural Resources, Manila, Philippines through the Coastal

brackish-water ponds are either titled or unaccounted. The appalling state of mangroves and brackish-water ponds in the Philippines results to continued loss of goods and services that these two systems could provide.

The strategies being proposed here aims to rationalize the environmental management of mangroves and brackish-water ponds in the Philippines. These strategies may be divided into three: 1) for brackish-water ponds with valid legal instruments and fish yield is still optimal, a more sustainable way of production must be adopted; 2) for ponds without legal instruments but fish yield is still bio-economically important, production must be sustainably optimized and legalized, and pond size may be reduced to as small as possible to maintain mangrove ecological health; and 3) for ponds with or without legal instrument and production is not anymore necessary, revegetation of the pond is being put forward. Of these options, the reforestation of idle and unproductive ponds and the practice of aquasilviculture may bring about the highest total economic values for these brackish-water ponds. The implementation of these options may not be straightforward and may need a conscious and concerted effort of different government agencies, academe and private institutions for an ecosystem based management approaches. These approaches should include mapping, inventory, status assessment and reprogramming and financing of existing management program.

With its current status, the vulnerability of mangroves to unsustainable anthropogenic activities (i.e. conversion to aquaculture areas, wood cutting, clearing for coastal developments) and the impacts of climate change may continue to degrade this ecosystem. Addressing these impacts may need the urgent rehabilitation of idle and unproductive ponds as these may decrease the level of vulnerability of these mangrove areas and the coastal communities behind them to the ancillary impacts of climate change. In all these, the government should take a proactive role in consolidating and monitoring these efforts to increase its efficiency and effectivity at the national scale as the present issues and problems on mangroves and brackish-water ponds in the Philippines cannot be appropriately addressed at the local scale.

#### **7. References**


http://www.bfar.da.gov.ph/services/CRS\_regulatory\_svcs/listingoffla.htm


brackish-water ponds are either titled or unaccounted. The appalling state of mangroves and brackish-water ponds in the Philippines results to continued loss of goods and services

The strategies being proposed here aims to rationalize the environmental management of mangroves and brackish-water ponds in the Philippines. These strategies may be divided into three: 1) for brackish-water ponds with valid legal instruments and fish yield is still optimal, a more sustainable way of production must be adopted; 2) for ponds without legal instruments but fish yield is still bio-economically important, production must be sustainably optimized and legalized, and pond size may be reduced to as small as possible to maintain mangrove ecological health; and 3) for ponds with or without legal instrument and production is not anymore necessary, revegetation of the pond is being put forward. Of these options, the reforestation of idle and unproductive ponds and the practice of aquasilviculture may bring about the highest total economic values for these brackish-water ponds. The implementation of these options may not be straightforward and may need a conscious and concerted effort of different government agencies, academe and private institutions for an ecosystem based management approaches. These approaches should include mapping, inventory, status assessment and reprogramming and financing of

With its current status, the vulnerability of mangroves to unsustainable anthropogenic activities (i.e. conversion to aquaculture areas, wood cutting, clearing for coastal developments) and the impacts of climate change may continue to degrade this ecosystem. Addressing these impacts may need the urgent rehabilitation of idle and unproductive ponds as these may decrease the level of vulnerability of these mangrove areas and the coastal communities behind them to the ancillary impacts of climate change. In all these, the government should take a proactive role in consolidating and monitoring these efforts to increase its efficiency and effectivity at the national scale as the present issues and problems on mangroves and brackish-water ponds in the Philippines cannot be appropriately

Alongi, D.M. (2002). Present state and future of world's mangrove forests. *Environmental* 

Alongi, D.M. (2008). Mangrove forests: Resilience, protection from tsunamis, and responses

Bureau of Fisheries and Aquatc Resources. (n.d.) List of FLAs duly issued by DA. In: *Bureau* 

Dahdouh-Guebas, F. et al. (2005). How effective were mangroves as a defense against the

to global climate change. *Estuarine, Coastal and Shelf Science* 76, 1-13. Barbier , E.B. (2000). Valuing the environment as input: review of applications to mangrove

*of Fisheries and Aquatic Resources,* June 27, 2011, Available from: http://www.bfar.da.gov.ph/services/CRS\_regulatory\_svcs/listingoffla.htm Cruz, P.S. (1997). Aquaculture Feed and Fertilizer Resource Atlas of the Philippines. *FAO* 

fishery linkages. *Ecological Economics* 35: 47-61.

recent tsunami? *Current Biology* 15 (12): 443-447.

*Fisheries Technical Paper-T366*, 259pp.

that these two systems could provide.

existing management program.

addressed at the local scale.

*Conservation* 29(3): 331-349.

**7. References** 


**4** 

*1Croatia 2,3Italy* 

**Manila Clam (***Tapes philippinarum* 

**of Marano and Grado (Northern** 

**Adams & Reeve, 1852) in the Lagoon** 

**Adriatic Sea, Italy): Socio-Economic** 

Barbara Sladonja1, Nicola Bettoso2, Aurelio Zentilin3, Francesco Tamberlich2 and Alessandro Acquavita2

*3Almar Soc. Coop. Agricola a.r.l., I-33050 Marano Lagunare (UD)* 

*1Institute of Agriculture and Tourism Poreč, Poreč, 2ARPA FVG-Osservatorio Alto Adriatico, Trieste* 

**and Environmental Pathway of a Shell Farm** 

Manila clam is a subtropical to low boreal species of the western Pacific, distributed in temperate areas of Europe. The natural populations are distributed in the Philippines, the South China and China Seas, Yellow Sea, Sea of Japan, the Sea of Okhotsk, and around the Southern Kuril Island (Scarlato, 1981). Its culture was initiated in those areas from the initial

As a species of commercial value, Manila clam has been introduced to several parts of the world, to become permanently established in several areas. The species was accidentally introduced the 1930's to the Pacific coast of North America along Pacific oyster *Crassostrea gigas* seed import (Chew, 1989). The species naturally spread the Pacific coast from California to British Colombia (Magoon & Vining, 1981). Besides public fisheries, hatchery production has facilitated Japanese carpet shell culture along the Pacific coastline. Manila clam was also transferred from Japan to Hawaiian waters early in the 20th century, where wild populations still occur. Overfishing and irregular yields of the native (European) grooved carpet shell, *Ruditapes decussatus*, led to imports of *R. philippinarum* into European

In 1972, the species was introduced into France by a commercial hatchery where they cultivated since the early 1980's (Goulletquer, 1997). The aquaculture development was facilitated by commercial hatcheries and additional imports from the United Kingdom using broodstock from Oregon (USA), resulted with numerous transfers within the European Union borders (Portugal, Italy, Ireland, Spain). Moreover, aquaculture experiments resulted in seed imports into Belgium, Germany, Israel, Tahiti, Tunisia, (Cesari & Pelizzato, 1985;

traditional fishing activities by the collection of wild seeds.

**1. Introduction** 

waters.

Shpigel & Friedman, 1990).

