**4. Harvesting**

Limpets and topshells are collected by hand, in the intertidal zone by the local population (traditional harvesting) and in the subtidal zone by snorkelers executing several dives per day (commercial harvesting), from 1 to 6 m deep (x ̅= 1.74 ± 1.31). The harvesting fleet operates preferentially on the northern coast of Madeira and Desertas Islands (**Figure 2**), the least accessible zones, while traditional harvesters collect limpets from all around the island preferably in areas with easy access and milder sea conditions.

The harvest of limpets in the archipelago of Madeira is operated from April to November for limpets and all year round for topshells mostly by small vessels (<10 m). Between 1990 and 2017, the number of vessels operating on the harvesting of gastropods was reduced from 17 (1990) to 9 (2017) (**Figure 3**). The observed reduction in the number of vessels and licenses results from the implementation of regulation, which among other management measures included the gradual reduction in the number of fishing licenses and vessels in order to reduce the harvesting pressure on limpet stocks.

The majority of the fishing vessels have less than 10 m length (78%), and the remaining ranges between 10 and 12 m (11%) and between 12 and 18 m (11%). This artisanal fleet includes vessels of low tonnage (0.74–17.28 gross tonnage) and capacity between 11 and 136 KW, usually operating in nearby areas reachable in a short time.

Limpet harvest is deeply rooted in the local community and particularly on coastal fishing communities representing an additional revenue source for many families, thus contributing to the local economy. The number of snorkelers per fishing vessel, between 2008 and 2017, varied between two and eight depending on the vessel size (x ̅=4.9 ± 1.29). The number of professional harvesters registered per vessel and nonprofessional harvesters (15 kg/person/day) decreased over the study period following the management measures implemented (**Figure 4**).

A remarkable proportion of the Madeiran fishing fleet focuses solely on the harvesting of gastropods; nevertheless due to the implementation of a closed season, some fishing fleets operate with two or three métiers. In 2017, 56% of the fishing fleet operated exclusively in the harvesting of gastropods; 33% operated with 3 métiers and 11% with 2 métiers (**Figure 5**). The complementary métiers were essentially directed to the capture of tuna fish and demersal fish.

**153**

**Figure 3.**

*Madeira.*

**4.1 Species and yields**

**Figure 4.**

*and 2018.*

In the archipelago of Madeira, limpets are mostly harvested by scuba diving in a mixed exploitation of *P. aspera* and *P. candei* with relevant commercial importance [13, 14] for the involved population. This activity represented approximately 1.5% of the total of the fisheries and 2% of the total of the economic value (€) in 2017, reaching an average value of 4 € per Kg [3]. In 2011, this activity represented *ca.* 5% of the total economic value (€) of the fisheries which landed in the archipelago of Madeira.

*Number of professional and nonprofessional harvesters registered in the archipelago of Madeira between 2016* 

*Artisanal Harvest of Shellfish in the Northeastern Atlantic: The Example of Limpet…*

*Number of fishing vessels operating in the harvesting of limpets from 1990 to 2017 in the archipelago of* 

*DOI: http://dx.doi.org/10.5772/intechopen.85728*

*Artisanal Harvest of Shellfish in the Northeastern Atlantic: The Example of Limpet… DOI: http://dx.doi.org/10.5772/intechopen.85728*

*Invertebrates - Ecophysiology and Management*

Limpets and topshells are collected by hand, in the intertidal zone by the local population (traditional harvesting) and in the subtidal zone by snorkelers executing several dives per day (commercial harvesting), from 1 to 6 m deep (x ̅= 1.74 ± 1.31). The harvesting fleet operates preferentially on the northern coast of Madeira and Desertas Islands (**Figure 2**), the least accessible zones, while traditional harvesters collect limpets from all around the island preferably in areas with easy access and

The harvest of limpets in the archipelago of Madeira is operated from April to November for limpets and all year round for topshells mostly by small vessels (<10 m). Between 1990 and 2017, the number of vessels operating on the harvesting of gastropods was reduced from 17 (1990) to 9 (2017) (**Figure 3**). The observed reduction in the number of vessels and licenses results from the implementation of regulation, which among other management measures included the gradual reduction in the number of fishing licenses and vessels in order to reduce the harvesting

The majority of the fishing vessels have less than 10 m length (78%), and the remaining ranges between 10 and 12 m (11%) and between 12 and 18 m (11%). This artisanal fleet includes vessels of low tonnage (0.74–17.28 gross tonnage) and capacity between 11 and 136 KW, usually operating in nearby areas reachable in a

Limpet harvest is deeply rooted in the local community and particularly on coastal fishing communities representing an additional revenue source for many families, thus contributing to the local economy. The number of snorkelers per fishing vessel, between 2008 and 2017, varied between two and eight depending on the vessel size (x ̅=4.9 ± 1.29). The number of professional harvesters registered per vessel and nonprofessional harvesters (15 kg/person/day) decreased over the study

A remarkable proportion of the Madeiran fishing fleet focuses solely on the harvesting of gastropods; nevertheless due to the implementation of a closed season, some fishing fleets operate with two or three métiers. In 2017, 56% of the fishing fleet operated exclusively in the harvesting of gastropods; 33% operated with 3 métiers and 11% with 2 métiers (**Figure 5**). The complementary métiers were

period following the management measures implemented (**Figure 4**).

essentially directed to the capture of tuna fish and demersal fish.

*Proportion of harvesting events of limpets per zone based on data from logbooks.*

**4. Harvesting**

milder sea conditions.

pressure on limpet stocks.

short time.

**152**

**Figure 2.**

*Number of fishing vessels operating in the harvesting of limpets from 1990 to 2017 in the archipelago of Madeira.*

**Figure 4.**

*Number of professional and nonprofessional harvesters registered in the archipelago of Madeira between 2016 and 2018.*

#### **4.1 Species and yields**

In the archipelago of Madeira, limpets are mostly harvested by scuba diving in a mixed exploitation of *P. aspera* and *P. candei* with relevant commercial importance [13, 14] for the involved population. This activity represented approximately 1.5% of the total of the fisheries and 2% of the total of the economic value (€) in 2017, reaching an average value of 4 € per Kg [3]. In 2011, this activity represented *ca.* 5% of the total economic value (€) of the fisheries which landed in the archipelago of Madeira.

**Figure 5.**

*Proportion of métiers operated by the fishing vessels involved in the harvesting of gastropods in the archipelago of Madeira.*

#### **Figure 6.**

*Representation of landings (tonnes) and economic value (1000 euros) of limpets from 1990 to 2017 in the archipelago of Madeira.*

The commercial landings in weight of limpets harvest varied from *ca.* 5 tonnes in 1990 to *ca.* 111 tonnes in 2017 (**Figure 6**). The maximum value landed was 150 tonnes in 2015 yielding a first auction sale value of 0.7 M€. The decrease in landings in 2016 and 2017 is related to the increase of the closed season from 3 to 4 months, reducing the harvesting activity in 1 month which was reflected in the annual landing values. Data from 1990 to 2006 needs to be analyzed carefully since limpet harvesting was not regulated and landing obligation was not mandatory.

The limpets landed in Madeira are for internal consumption and, to a minor extent, for exportation, mainly to the archipelago of Azores. However, data on the exportations of limpets are not available and as such are not possible to determine accurately.

**155**

**Figure 7.**

*Artisanal Harvest of Shellfish in the Northeastern Atlantic: The Example of Limpet…*

kg is still very attractive for the professionals involved in this activity.

The average annual value of limpets per kg landed in the archipelago of Madeira fluctuated considerably, from 1990 to 2017, increasing from 1.80 € in 1990 to 3.65 € in 2017 (x ̅=3.33 ± 1.25 €). For this period the average annual price varied from 1.21 € in 1990 to 5.90 € in 2008 (**Figure 7**). Since 2008, the value per kg decreased due to the increase in landings and the demand for this resource. Even so, the value per

The harvesting effort, represented by the number of days employed in the harvest of limpets, decreased from 1448 days in 2008 to 655 days in 2017. However, in general the reduction in fishing effort contrary to what would be expected led to an increase in the landings (*ca.* 98 tonnes in 2008 to *ca.* 111 tonnes in 2017). From 2013 to 2017, the oscillations on the landings were related to different sea conditions among years, e.g., in 2015 the milder sea conditions resulted in more 361 days at the sea. The increase verified in the landings seems to result from the management measures implemented in 2006 (**Figure 8**). In fact, if the management measures implemented were successful, then it is expected that the exploited stocks have greater biomass, not only in density but also larger individuals are supposedly more abundant which in return means that lower effort returns similar

The highest proportion of landings of limpets, for the considered time period,

In the archipelago of Madeira, landings of limpet commercially harvested, between 1990 and 2017, occurred in 10 ports, namely, Funchal, Câmara de Lobos, Calheta, Madalena do Mar, Paúl do Mar, Porto Moniz, Santa Cruz, Machico, Caniçal, and Porto Santo. The total landings per port in tonnes are represented in **Figure 10**. During this period, Porto Moniz, Funchal, Caniçal, and Paúl do Mar were the most important ports representing approximately 96% of the limpets landed in 1990 and 100% of the limpets landed in 2017.

*Average annual price of the limpets landed in the archipelago of Madeira from 1990 to 2017.*

occurred from May to August, corresponding to the months with better sea conditions in the archipelago of Madeira (**Figure 9**). The comparison between monthly landings before and after the implementation of the closed season showed that the highest proportion of landings remained identical between the two periods, except for the months of the closed season, when limpet harvesting

*DOI: http://dx.doi.org/10.5772/intechopen.85728*

or superior yields.

is not allowed.

*Artisanal Harvest of Shellfish in the Northeastern Atlantic: The Example of Limpet… DOI: http://dx.doi.org/10.5772/intechopen.85728*

The average annual value of limpets per kg landed in the archipelago of Madeira fluctuated considerably, from 1990 to 2017, increasing from 1.80 € in 1990 to 3.65 € in 2017 (x ̅=3.33 ± 1.25 €). For this period the average annual price varied from 1.21 € in 1990 to 5.90 € in 2008 (**Figure 7**). Since 2008, the value per kg decreased due to the increase in landings and the demand for this resource. Even so, the value per kg is still very attractive for the professionals involved in this activity.

The harvesting effort, represented by the number of days employed in the harvest of limpets, decreased from 1448 days in 2008 to 655 days in 2017. However, in general the reduction in fishing effort contrary to what would be expected led to an increase in the landings (*ca.* 98 tonnes in 2008 to *ca.* 111 tonnes in 2017). From 2013 to 2017, the oscillations on the landings were related to different sea conditions among years, e.g., in 2015 the milder sea conditions resulted in more 361 days at the sea. The increase verified in the landings seems to result from the management measures implemented in 2006 (**Figure 8**). In fact, if the management measures implemented were successful, then it is expected that the exploited stocks have greater biomass, not only in density but also larger individuals are supposedly more abundant which in return means that lower effort returns similar or superior yields.

The highest proportion of landings of limpets, for the considered time period, occurred from May to August, corresponding to the months with better sea conditions in the archipelago of Madeira (**Figure 9**). The comparison between monthly landings before and after the implementation of the closed season showed that the highest proportion of landings remained identical between the two periods, except for the months of the closed season, when limpet harvesting is not allowed.

In the archipelago of Madeira, landings of limpet commercially harvested, between 1990 and 2017, occurred in 10 ports, namely, Funchal, Câmara de Lobos, Calheta, Madalena do Mar, Paúl do Mar, Porto Moniz, Santa Cruz, Machico, Caniçal, and Porto Santo. The total landings per port in tonnes are represented in **Figure 10**. During this period, Porto Moniz, Funchal, Caniçal, and Paúl do Mar were the most important ports representing approximately 96% of the limpets landed in 1990 and 100% of the limpets landed in 2017.

**Figure 7.** *Average annual price of the limpets landed in the archipelago of Madeira from 1990 to 2017.*

*Invertebrates - Ecophysiology and Management*

**154**

**Figure 6.**

*archipelago of Madeira.*

**Figure 5.**

*of Madeira.*

The commercial landings in weight of limpets harvest varied from *ca.* 5 tonnes in 1990 to *ca.* 111 tonnes in 2017 (**Figure 6**). The maximum value landed was 150 tonnes in 2015 yielding a first auction sale value of 0.7 M€. The decrease in landings in 2016 and 2017 is related to the increase of the closed season from 3 to 4 months, reducing the harvesting activity in 1 month which was reflected in the annual landing values. Data from 1990 to 2006 needs to be analyzed carefully since limpet

*Representation of landings (tonnes) and economic value (1000 euros) of limpets from 1990 to 2017 in the* 

*Proportion of métiers operated by the fishing vessels involved in the harvesting of gastropods in the archipelago* 

The limpets landed in Madeira are for internal consumption and, to a minor extent, for exportation, mainly to the archipelago of Azores. However, data on the exportations of limpets are not available and as such are not possible to determine accurately.

harvesting was not regulated and landing obligation was not mandatory.

**Figure 8.** *Landings and harvesting effort from 2008 to 2017 in the harvesting of limpets in the archipelago of Madeira.*

Porto Moniz showed the highest annual limpet landings with 1.9 tonnes in 1990 and 76 tonnes in 2017, representing approximately 69% of the total landings of limpets in 2017 (**Figure 11**). Six fishing vessels landed *ca.* 96 tonnes representing

**Figure 9.**

*Proportion of landings of limpets per month before (1990–2007) and after (2008–2017) the implementation of management measures in the archipelago of Madeira.*

**157**

**Figure 11.**

**Figure 10.**

increasing in importance over the years.

*Landings of limpets per year considering the landing port.*

*Artisanal Harvest of Shellfish in the Northeastern Atlantic: The Example of Limpet…*

86% of the total of limpets landed in 2017. Since 2014, landings of commercially harvested limpets occur only in four ports (Porto Moniz, Caniçal, Paúl do Mar, and Funchal), mainly due to the proximity of the ports to the harvesting zones. The commercial landings of limpets (in weight) in the archipelago of Madeira increased from 12% in 1990 to 96% of the total of molluscs landed in this region (**Figure 12**). Since 1998, limpets represent >90% of the landed molluscs in weight,

The economic importance of limpets in the fisheries sector of the archipelago

of Madeira gradually increased over the years. In 1990, limpets represented

*DOI: http://dx.doi.org/10.5772/intechopen.85728*

*Total landings of limpets per port between 1990 and 2017.*

*Artisanal Harvest of Shellfish in the Northeastern Atlantic: The Example of Limpet… DOI: http://dx.doi.org/10.5772/intechopen.85728*

**Figure 10.** *Total landings of limpets per port between 1990 and 2017.*

#### **Figure 11.**

*Invertebrates - Ecophysiology and Management*

Porto Moniz showed the highest annual limpet landings with 1.9 tonnes in 1990 and 76 tonnes in 2017, representing approximately 69% of the total landings of limpets in 2017 (**Figure 11**). Six fishing vessels landed *ca.* 96 tonnes representing

*Landings and harvesting effort from 2008 to 2017 in the harvesting of limpets in the archipelago of Madeira.*

*Proportion of landings of limpets per month before (1990–2007) and after (2008–2017) the implementation of* 

**156**

**Figure 9.**

**Figure 8.**

*management measures in the archipelago of Madeira.*

*Landings of limpets per year considering the landing port.*

86% of the total of limpets landed in 2017. Since 2014, landings of commercially harvested limpets occur only in four ports (Porto Moniz, Caniçal, Paúl do Mar, and Funchal), mainly due to the proximity of the ports to the harvesting zones.

The commercial landings of limpets (in weight) in the archipelago of Madeira increased from 12% in 1990 to 96% of the total of molluscs landed in this region (**Figure 12**). Since 1998, limpets represent >90% of the landed molluscs in weight, increasing in importance over the years.

The economic importance of limpets in the fisheries sector of the archipelago of Madeira gradually increased over the years. In 1990, limpets represented

#### **Figure 12.**

*Landings of limpets and the landings of the total molluscs per year, between 1990 and 2017 in the archipelago of Madeira.*

approximately 26% of the total economic value landed for molluscs and in 2017 approximately 96%. Since 1991, limpets represent the majority of the landed value for molluscs. From 1998 to 2017, this resource represents over 90% of the landings of molluscs (**Figure 13**).

The traditional harvesting of limpets carried out by the local populations is not represented in the landings since current harvesting regulation does not require first auction sale for this activity (<3 kg/day/person), thus making it difficult to quantify the real impact of the traditional harvest on the exploited populations. Also, illegal harvest is not considered on the total of landings. Nonetheless, it is

#### **Figure 13.**

*Economic value of the landings of limpets and the economic value of the landings of the other molluscs per year, between 1990 and 2017 in the archipelago of Madeira.*

**159**

**Figure 14.**

*Artisanal Harvest of Shellfish in the Northeastern Atlantic: The Example of Limpet…*

known that commercial harvest occurs preferentially on certain locations (north coast of Madeira Island and around the Desertas), and, for these regions at least there is a better understanding of the harvesting effort on the exploited stocks. The topshell (*P. sauciatus*) harvest in the archipelago of Madeira is carried out unregulated and without auction obligation, and as such, the landings of this species are residual, being impossible to estimate the real harvesting effort exerted on this species [2]. The landings varied from *ca.* 3 kg (2015) to *ca.* 230 kg (1993) between 1991 and 2017, yielding annual landed values between 14 and 520 € (**Figure 14**). Usually this species is sold directly to the markets at very high prices,

Specific stock assessments for limpets in the archipelago of Madeira begun in the mid-2000s and were the basis for regulation of shellfish harvest in the region [11]. Nevertheless, due to the increasing interest in these molluscs, preliminary monitoring of limpet populations began in 1996. More recently, studies on the biology and stock assessment of *P. candei* and *P. aspera* were accomplished by Henriques et al.

The stocks of *P. candei* and *P. aspera* were found to be underexploited but with exploitation occurring near their maximum sustainable yield in the archipelago of Madeira. However, limpets' specific life traits, like slow growth rates and long life-span, make these molluscs extremely vulnerable to overexploitation, and as such continuous monitoring of the stocks and the enforcement of the existing harvest regulations must be accomplished if future overexploitation is to be avoided [13, 14]. Surveillance and enforcement of the closed season are also particularly important to avoid poaching and safeguard the reproduction of these species. Specifically, for *P. aspera* since this species is a protandrous hermaphrodite, and thus especially vulnerable to size selective harvest, since after reaching sexual maturation a percentage of males shifts to females, thus the removal of larger individuals will target primarily females leading to a decreased

*Landings and economic value of topshells from 1990 to 2017 in the archipelago of Madeira.*

*DOI: http://dx.doi.org/10.5772/intechopen.85728*

reaching prices, i.e., between 15 and 20 € per kg.

**4.2 Stock status**

[13] and Sousa et al. [14].

reproductive success.

*Artisanal Harvest of Shellfish in the Northeastern Atlantic: The Example of Limpet… DOI: http://dx.doi.org/10.5772/intechopen.85728*

known that commercial harvest occurs preferentially on certain locations (north coast of Madeira Island and around the Desertas), and, for these regions at least there is a better understanding of the harvesting effort on the exploited stocks.

The topshell (*P. sauciatus*) harvest in the archipelago of Madeira is carried out unregulated and without auction obligation, and as such, the landings of this species are residual, being impossible to estimate the real harvesting effort exerted on this species [2]. The landings varied from *ca.* 3 kg (2015) to *ca.* 230 kg (1993) between 1991 and 2017, yielding annual landed values between 14 and 520 € (**Figure 14**). Usually this species is sold directly to the markets at very high prices, reaching prices, i.e., between 15 and 20 € per kg.

#### **4.2 Stock status**

*Invertebrates - Ecophysiology and Management*

**158**

**Figure 13.**

of molluscs (**Figure 13**).

**Figure 12.**

*Madeira.*

*between 1990 and 2017 in the archipelago of Madeira.*

*Economic value of the landings of limpets and the economic value of the landings of the other molluscs per year,* 

approximately 26% of the total economic value landed for molluscs and in 2017 approximately 96%. Since 1991, limpets represent the majority of the landed value for molluscs. From 1998 to 2017, this resource represents over 90% of the landings

*Landings of limpets and the landings of the total molluscs per year, between 1990 and 2017 in the archipelago of* 

The traditional harvesting of limpets carried out by the local populations is not represented in the landings since current harvesting regulation does not require first auction sale for this activity (<3 kg/day/person), thus making it difficult to quantify the real impact of the traditional harvest on the exploited populations. Also, illegal harvest is not considered on the total of landings. Nonetheless, it is

Specific stock assessments for limpets in the archipelago of Madeira begun in the mid-2000s and were the basis for regulation of shellfish harvest in the region [11]. Nevertheless, due to the increasing interest in these molluscs, preliminary monitoring of limpet populations began in 1996. More recently, studies on the biology and stock assessment of *P. candei* and *P. aspera* were accomplished by Henriques et al. [13] and Sousa et al. [14].

The stocks of *P. candei* and *P. aspera* were found to be underexploited but with exploitation occurring near their maximum sustainable yield in the archipelago of Madeira. However, limpets' specific life traits, like slow growth rates and long life-span, make these molluscs extremely vulnerable to overexploitation, and as such continuous monitoring of the stocks and the enforcement of the existing harvest regulations must be accomplished if future overexploitation is to be avoided [13, 14]. Surveillance and enforcement of the closed season are also particularly important to avoid poaching and safeguard the reproduction of these species. Specifically, for *P. aspera* since this species is a protandrous hermaphrodite, and thus especially vulnerable to size selective harvest, since after reaching sexual maturation a percentage of males shifts to females, thus the removal of larger individuals will target primarily females leading to a decreased reproductive success.

**Figure 14.** *Landings and economic value of topshells from 1990 to 2017 in the archipelago of Madeira.*

Presently, some concerns persist regarding the management of the commercial exploitation of these two species in the region, namely, the lack of knowledge on the genetic connectivity between populations. In this sense, studies in this field are ongoing to establish proper conservation strategies considering connectivity or isolation of the populations. Another important concern relates to illegal poaching in the closed season and in MPAs and new conservation policies raising public awareness using innovative approaches involving not only decisionmakers but also the local communities which will be pivotal for the conservation of these species [12].

The first approach to assess the status of the stock of the topshell *P. sauciatus* in the archipelago of Madeira was held in 2018 although this species has been exploited since the fifteenth century. The stock of *P. sauciatus* seems to be moderately exploited in the region but vulnerable to the harvest of small specimens. Conservation measures on harvesting regulation, considering the biological and ecological specificities of this species in this region, are required to preserve the stock in the medium and long terms, and efforts in implementing it are currently underway.

## **5. Effects of management measures in limpet populations**

The implementation of limpet harvest management measures in the archipelago of Madeira was of paramount importance due to the life history traits of these species allied to their economic importance that results in a high harvesting pressure on these resources.

The continuous monitoring of the limpet populations over time allowed the regulators to readjust harvesting regulation in Madeira, namely, the closed season period that initially lasted from November to January and presently ranges from December to March, to protect more effectively the breeding period of limpet species. This continuous monitoring clearly maximizes the returns that can be achieved through the regulation of this activity; since the responses of exploited stocks to harvest are continually changing, regulation has to adapt to these changes in order to promote its sustainability. The reduction of the number of harvesting licenses, the prohibition to capture immature individuals (<40 mm shell length), and the catch limits have also contributed to the increase of the mean size of the specimens, to the recovery of the size composition and to the increase of the abundance of the limpets' populations, in the archipelago of Madeira [3].

Conservation measures prompted an overall improvement of the exploited stocks on both exploited limpet species in Madeira. Comparative studies on the effectiveness of the implemented management measures demonstrated that the stocks of *P. aspera* and *P. candei* are slightly recovering since regulatory measures entered into force. The harvesting regulation was conducted to an increase in limpets mean shell length and to a more balanced size structure of the populations and a dominance of reproductive individuals. This effect was more noticeable in *P. aspera* populations due to the greater exploitation pressure exerted on this species [3].

The implemented management measures and the current levels of enforcement in the archipelago of Madeira showed positive results contrarily to those in the archipelago of Azores and the Canaries where management and enforcement were insufficient to protect the exploited limpet populations [15, 16].

The management measures led to an increase of 14% in proportion of reproductive individuals and to an increase in the size and age of first maturity for both species. A shift from a biased sex ratio before harvesting regulation to a balanced sex ratio after regulation occurred for *P. aspera* (R.S., pers. obs.).

Marine protected areas also contributed to the protection of limpet populations in the archipelago of Madeira. The increase of size-at-first maturity, shell size,

**161**

*Artisanal Harvest of Shellfish in the Northeastern Atlantic: The Example of Limpet…*

required to confirm this possible positive effect of MPAs on limpet stocks.

balanced size composition, and capture per unit effort (CPUE) is evident in MPAs when compared to exploited populations. Also in the oldest and well-enforced MPAs, a high representation of large adults and more balanced populations for both limpet species (R.S., per. Obs.) was found. In fact, MPAs play a pivotal role in the recovery of the exploited stocks of limpets in the archipelago of Madeira, considering their potential to promote replenishment and recruitment in nearby coastal areas where limpets are or have been heavily exploited. However, further studies are

The harvesting of limpets in the archipelago of Madeira is protected by legislation that provides the basis for a sustainable exploitation. However, it is still very common for violations to the current management policies and regulations which are punishable with the application of penalties when detected by the local authorities to occur. The two major weaknesses in this regard are the lack of compliance by the fishermen, which is mostly due to the lack of knowledge about the importance of the implemented management measures, and the poor enforcement by the regional authorities. A greater effort in the enforcement of regulations is required to ensure compliance of the fishing communities and an increase of the surveillance by the authorities to discourage illegal harvesting of these molluscs. Concerning topshells it is crucial to establish management measures on the harvesting of this resource to promote a sustainable exploitation in a medium and

The ecological role that these key resources play in the coastal ecosystem and the importance of their survival not only from a conservational perspective but also economical needs to clearly transmitted to the fishermen and the general public, stakeholders, and authorities. This can be achieved through a proximity approach promoting training and involvement of all interested parties in the management and protection of these species. Promoting the awareness and advice to consumers in order to reduce illegal harvesting. Also, by instilling entrepreneurial spirit in fishermen by complementing their fishing activity with tourism through vessel trips and dives, adding value to these resources and increasing the

The implementation of obligatory species-specific landings for limpets is urgent to more accurately quantify the landings of each species and monitor the exploited

The authors are grateful to the Fisheries Research Service (DSI) of the Regional Directorate of Fisheries of the Autonomous Region of Madeira for providing the information used in this work. The first author (RS) was supported by a grant from ARDITI OOM/2016/010 (M1420-01-0145-FEDER-000001-Observatório Oceânico da Madeira-OOM) and the second author (JV) by a grant from FCT (SFRH/BSAB/143056/2018). The present study has been also supported by the

The encouragement of aquaculture investments and post-harvest facilities will reduce fishing pressure on exploited gastropods in the archipelago of Madeira and open the possibility of stock replenishment by reintroduction of cultured individuals to their natural habitat. This would also positively contribute to the socioeconomic development of the region, not only through production but also through job creation.

stocks, since they are landed together as a mixed exploitation.

*DOI: http://dx.doi.org/10.5772/intechopen.85728*

**6. Conclusions**

long term.

fishermen income.

**Acknowledgements**

*Artisanal Harvest of Shellfish in the Northeastern Atlantic: The Example of Limpet… DOI: http://dx.doi.org/10.5772/intechopen.85728*

balanced size composition, and capture per unit effort (CPUE) is evident in MPAs when compared to exploited populations. Also in the oldest and well-enforced MPAs, a high representation of large adults and more balanced populations for both limpet species (R.S., per. Obs.) was found. In fact, MPAs play a pivotal role in the recovery of the exploited stocks of limpets in the archipelago of Madeira, considering their potential to promote replenishment and recruitment in nearby coastal areas where limpets are or have been heavily exploited. However, further studies are required to confirm this possible positive effect of MPAs on limpet stocks.

## **6. Conclusions**

*Invertebrates - Ecophysiology and Management*

Presently, some concerns persist regarding the management of the commercial exploitation of these two species in the region, namely, the lack of knowledge on the genetic connectivity between populations. In this sense, studies in this field are ongoing to establish proper conservation strategies considering connectivity or isolation of the populations. Another important concern relates to illegal poaching in the closed season and in MPAs and new conservation policies raising public awareness using innovative approaches involving not only decisionmakers but also the local communities which will be pivotal for the conservation of these species [12]. The first approach to assess the status of the stock of the topshell *P. sauciatus* in the archipelago of Madeira was held in 2018 although this species has been exploited since the fifteenth century. The stock of *P. sauciatus* seems to be moderately exploited in the region but vulnerable to the harvest of small specimens. Conservation measures on harvesting regulation, considering the biological and ecological specificities of this species in this region, are required to preserve the stock in the medium and

The implementation of limpet harvest management measures in the archipelago of Madeira was of paramount importance due to the life history traits of these species allied to their economic importance that results in a high harvesting pressure on

The continuous monitoring of the limpet populations over time allowed the regulators to readjust harvesting regulation in Madeira, namely, the closed season period that initially lasted from November to January and presently ranges from December to March, to protect more effectively the breeding period of limpet species. This continuous monitoring clearly maximizes the returns that can be achieved through the regulation of this activity; since the responses of exploited stocks to harvest are continually changing, regulation has to adapt to these changes in order to promote its sustainability. The reduction of the number of harvesting licenses, the prohibition to capture immature individuals (<40 mm shell length), and the catch limits have also contributed to the increase of the mean size of the specimens, to the recovery of the size composition and to the increase of the abundance of the

Conservation measures prompted an overall improvement of the exploited stocks on both exploited limpet species in Madeira. Comparative studies on the effectiveness of the implemented management measures demonstrated that the stocks of *P. aspera* and *P. candei* are slightly recovering since regulatory measures entered into force. The harvesting regulation was conducted to an increase in limpets mean shell length and to a more balanced size structure of the populations and a dominance of reproductive individuals. This effect was more noticeable in *P. aspera* populations due to the greater

The implemented management measures and the current levels of enforcement

The management measures led to an increase of 14% in proportion of reproduc-

Marine protected areas also contributed to the protection of limpet populations

in the archipelago of Madeira showed positive results contrarily to those in the archipelago of Azores and the Canaries where management and enforcement were

tive individuals and to an increase in the size and age of first maturity for both species. A shift from a biased sex ratio before harvesting regulation to a balanced

in the archipelago of Madeira. The increase of size-at-first maturity, shell size,

insufficient to protect the exploited limpet populations [15, 16].

sex ratio after regulation occurred for *P. aspera* (R.S., pers. obs.).

long terms, and efforts in implementing it are currently underway.

**5. Effects of management measures in limpet populations**

limpets' populations, in the archipelago of Madeira [3].

exploitation pressure exerted on this species [3].

**160**

these resources.

The harvesting of limpets in the archipelago of Madeira is protected by legislation that provides the basis for a sustainable exploitation. However, it is still very common for violations to the current management policies and regulations which are punishable with the application of penalties when detected by the local authorities to occur. The two major weaknesses in this regard are the lack of compliance by the fishermen, which is mostly due to the lack of knowledge about the importance of the implemented management measures, and the poor enforcement by the regional authorities. A greater effort in the enforcement of regulations is required to ensure compliance of the fishing communities and an increase of the surveillance by the authorities to discourage illegal harvesting of these molluscs. Concerning topshells it is crucial to establish management measures on the harvesting of this resource to promote a sustainable exploitation in a medium and long term.

The ecological role that these key resources play in the coastal ecosystem and the importance of their survival not only from a conservational perspective but also economical needs to clearly transmitted to the fishermen and the general public, stakeholders, and authorities. This can be achieved through a proximity approach promoting training and involvement of all interested parties in the management and protection of these species. Promoting the awareness and advice to consumers in order to reduce illegal harvesting. Also, by instilling entrepreneurial spirit in fishermen by complementing their fishing activity with tourism through vessel trips and dives, adding value to these resources and increasing the fishermen income.

The implementation of obligatory species-specific landings for limpets is urgent to more accurately quantify the landings of each species and monitor the exploited stocks, since they are landed together as a mixed exploitation.

The encouragement of aquaculture investments and post-harvest facilities will reduce fishing pressure on exploited gastropods in the archipelago of Madeira and open the possibility of stock replenishment by reintroduction of cultured individuals to their natural habitat. This would also positively contribute to the socioeconomic development of the region, not only through production but also through job creation.

#### **Acknowledgements**

The authors are grateful to the Fisheries Research Service (DSI) of the Regional Directorate of Fisheries of the Autonomous Region of Madeira for providing the information used in this work. The first author (RS) was supported by a grant from ARDITI OOM/2016/010 (M1420-01-0145-FEDER-000001-Observatório Oceânico da Madeira-OOM) and the second author (JV) by a grant from FCT (SFRH/BSAB/143056/2018). The present study has been also supported by the

UE European Regional Development Fund in the framework of the Projects MARISCOMAC (MAC/2.3d/097), MACAROFOOD (MAC/2.3d/015), the Regional Government of Madeira, and FCT through the strategic project UID/ MAR/04292/2019 granted to MARE.
