White Leg Prawn
Escapes and Introductions
Escapees from aquaculture facilities can potentially impact on habitats and species in the receiving waters. may affect the genetics of local populations in its native range via interbreeding and the introduction of disease to wild stocks. Where farmed as a non-native species, escaped vannamei may potentially establish themselves in the wild and compete with native prawn species.
Authorities can ensure that new warm water prawn farms locate in areas where the species farmed is either indigenous or where self-recruiting populations have already established. If neither of these conditions applies then the licence or permit should require evidence that escapees will not establish or farm containment systems will prevent escape.
The contribution of non-native species to the growth of the global aquaculture industry and the economic benefits that it has brought to many countries is large, but minimising escapes of non-native aquaculture species must be a high priority for resource managers, conservationists and the aquaculture industry1.
Although there have been numerous escapes from prawn farms into non-native waters, and this species is regularly caught in the wild around Asia, it is unproven whether breeding populations have established outside its natural range2.
Losses due to escapes also represent a considerable financial loss to a farm, so it is in their interest to prevent escapes as much as possible.
There has been increasing regulation, uptake of Best Management Practices (BMPs), codes of conduct or practices and certification schemes in warm water prawn aquaculture which help in tackling escape issues. To reduce escape risks farms should have trapping devices such as screens and grills on all water inlets, outlets and drainage channels that are suitably sized to match the size of the stock. These screens should be regularly inspected, maintained and such actions recorded. Pond embankments, bunds, and levees should be of adequate height and standard to retain stocks during periods of flood and regularly inspected and maintained. There should be no intentional release of stock from the farm.
Importation and movements of vannamei broodstock or post-larvae should be from trusted and registered sources, disease free and meet all appropriate requirements and guidelines.