Agriculture and Environment: Shrimp

Environmental Impacts of Production: Nonnative Species

Little is known about the overall impact of the introduction of shrimp species from aquaculture.

For some time, the species Penaeus vannamei from the west coast of Latin America has been farmed along the Caribbean and Atlantic coasts from South Carolina to Brazil and more recently in Asia.


Likewise, shrimp of the species P. monodon from Asia have been transported throughout Asia and brought to Latin America. P. monodon shrimp from Africa have been taken to Asia and the Pacific, and there has been a flow of this same species from Southeast Asia to South Asia and vice versa. Escapes, however, have not yet shown up in wild shrimp catch.

"Genetic pollution"
The introduction of shrimp from different regions, even of the same species, introduces new DNA and the characteristics that have not evolved in situ.

These interactions are probably insignificant within ponds, but when shrimp escape during winter exchange or harvest they could cause genetic pollution that could alter the inbred characteristics, and perhaps the viability, of wild populations.

Spread of diseases
The introduction of disease pathogens from other areas is equally important. Diseases previously found only in China and Taiwan, China have now spread throughout Asia and even into Latin America, where they have caused billions of dollars in damage each year. The impact of disease pathogens on wild stocks is not documented, but anecdotal information suggests that it may be serious.

Drastic reduction in shrimp populations
For example, in 1992-93 when diseases reduced shrimp aquaculture production in China by 60-70%, the production of wild-caught shrimp in that country also declined by 90%. It is not clear whether the disease was transmitted from the wild to the ponds or vice versa, but there does seem to be some direct relationship.

Pathogens can be introduced through the transportation of infected larvae or brood stock that are released without proper quarantine and handling. In addition, diseases have been found to be viable in processed frozen product that is shipped to another region for further processing.

 

Credits

Extracts from "World Agriculture & Environment" by Jason Clay - buy the book online from Island Press

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