**3. Can escapees survive the natural environmental conditions?**

Pacific white shrimp *P. vannamei* is the most economically important species for aquaculture in extensive, semi-intensive, and intensive systems in many parts of the world [46, 47] due to several advantages compared with other cultured shrimps. These are largely associated with the ability to close the life cycle and produce broodstock within the culture ponds, rapid growth rate (at up to 3 g/week),

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*Ecological and Social Impacts of Aquacultural Introduction to Philippines Waters of Pacific…*

 in controlled recirculated tank culture), tolerance of low salinities (0.5–45 ppt) and temperatures (15–33°C), lower protein requirements (20–35%) and therefore production costs, and high survival (50–60%) during larval rearing [29]. However, the question remains if they can survive in the natural environment wherein

It can be assumed that *P. vannamei* escapees can survive the natural environmental conditions based from early reports [23–31, 34, 35]. For instance, a large number were released accidentally from a shrimp farm in Texas in 1991, and the escapees were caught up to 65 miles from the shore [48]. The presence of the shrimp in commercial catches in South Carolina was also reported in 1989 and 1990 [49]. On the other hand, Medina-Reyna [50] reported the growth and emigration of the shrimp in the Mar Muerto Lagoon, which is one of the largest nursing grounds for this species in Mexico. Reports were all related to the ability of the shrimp to tolerate a wide range of salinity. Recently, the study of Chavanich et al. [51] results indicated that *P. vannamei* escapees can likely survive the environmental conditions of the Bangpakong River and its river mouth. A toxicological experiment was conducted to evaluate the physiological limits of larvae and juveniles of *P. vannamei* and *P. monodon* to extreme salinity and pH changes [44]. Results showed that both species can tolerate a wide range of salinity and pH. For both life stages, *P. vannamei* could tolerate a wider range and more extreme changes of salinity and pH than *P. monodon*. The data suggested that both life stages of *P. vannamei* could adapt to estuarine conditions of the Bangpakong River where water quality, especially salinity, can fluctuate dramatically. The shrimp is also capable of migrating to the river mouth; in times the Bangpakong River may approach zero salinity at most sites during the wet season (June to November). This eventually resulted in an increase in abundance and size overtime of the shrimp captured in the river and near the river mouth. More likely, this scenario already existed in Buguey Lagoon in Cagayan since the shrimp has been a part of fishermen catch in the area, and this could be true in other estuaries and rivers in the Philippines wherein the shrimp hatcheries

in pond culture, and even as high as 400/

*DOI: http://dx.doi.org/10.5772/intechopen.91775*

tolerance of high stocking density (150/m2

adverse conditions are present.

and farms are located.

**4. Can escapees establish a natural population?**

According to CABI [52], the species itself is not considered a major threat to biodiversity and does not appear to have formed breeding populations. Briggs et al. [29] added that despite the fact that the species has been widely introduced, a comprehensive study of the literature carried out for this report and the information available from other countries in Asia and in the Americas did not find any evidence of the shrimp becoming established in the wild outside of its range (i.e., it may not become an easily "invasive" species). However, there is a need for further field research, as there was insufficient information available on the natural breed-

Understanding the biology of *P. vannamei* is vital in order to know whether this animal once escape can establish a natural population that is crucial to the environment. However, there is limited information on the biology of this animal and is neglected during the last two decades. According to Dugassa and Gaetan [53], *P. vannamei* lives in tropical marine habitats, and the adults of this species live and spawn in the ocean. However, the larvae and juveniles are usually found in inshore water areas such as coastal estuaries, lagoons, or mangrove areas. The shrimp females grow faster than the male of this species. The matured female weighing 30–45 g can spawn 100,000–250,000 eggs. The shrimp life cycle is very complex, and it

ing habits of the shrimp to make any further assessment of this issue.

m2

### *Ecological and Social Impacts of Aquacultural Introduction to Philippines Waters of Pacific… DOI: http://dx.doi.org/10.5772/intechopen.91775*

tolerance of high stocking density (150/m2 in pond culture, and even as high as 400/ m2 in controlled recirculated tank culture), tolerance of low salinities (0.5–45 ppt) and temperatures (15–33°C), lower protein requirements (20–35%) and therefore production costs, and high survival (50–60%) during larval rearing [29]. However, the question remains if they can survive in the natural environment wherein adverse conditions are present.

It can be assumed that *P. vannamei* escapees can survive the natural environmental conditions based from early reports [23–31, 34, 35]. For instance, a large number were released accidentally from a shrimp farm in Texas in 1991, and the escapees were caught up to 65 miles from the shore [48]. The presence of the shrimp in commercial catches in South Carolina was also reported in 1989 and 1990 [49]. On the other hand, Medina-Reyna [50] reported the growth and emigration of the shrimp in the Mar Muerto Lagoon, which is one of the largest nursing grounds for this species in Mexico. Reports were all related to the ability of the shrimp to tolerate a wide range of salinity. Recently, the study of Chavanich et al. [51] results indicated that *P. vannamei* escapees can likely survive the environmental conditions of the Bangpakong River and its river mouth. A toxicological experiment was conducted to evaluate the physiological limits of larvae and juveniles of *P. vannamei* and *P. monodon* to extreme salinity and pH changes [44]. Results showed that both species can tolerate a wide range of salinity and pH. For both life stages, *P. vannamei* could tolerate a wider range and more extreme changes of salinity and pH than *P. monodon*. The data suggested that both life stages of *P. vannamei* could adapt to estuarine conditions of the Bangpakong River where water quality, especially salinity, can fluctuate dramatically. The shrimp is also capable of migrating to the river mouth; in times the Bangpakong River may approach zero salinity at most sites during the wet season (June to November). This eventually resulted in an increase in abundance and size overtime of the shrimp captured in the river and near the river mouth. More likely, this scenario already existed in Buguey Lagoon in Cagayan since the shrimp has been a part of fishermen catch in the area, and this could be true in other estuaries and rivers in the Philippines wherein the shrimp hatcheries and farms are located.
