Implications of the introduction and transfer of non-indigenous marine species with particular reference to Canadian marine aquaculture

A relatively new and emerging field relating to the world's oceans has been the identification of risks associated with the introduction of exotic or non-indigenous species. There are numerous pathways for the introduction, either accidentally or intentionally, of non-indigenous species to marine ecosystems. These pathways include aquaculture activities, ship's ballast water, aquarium trade, and individual release. The relative importance of specific dispersal methods varies both temporally and spatially, but each plays a significant role in the introduction and dispersal of marine species throughout coastal environments. Many studies have focused on the impacts of these invasions but relatively few have analyzed the biological, physical, and socioeconomic impacts of non-indigenous species on aquaculture operations. Therefore, the objective of this report is to analyze case studies that focus on the implications, either positive or negative, of non-indigenous marine species on specific ecosystems and how they affect marine aquaculture, particularly in Canada. -- Aquaculture is a growing industry worldwide and will likely play a significant role in meeting the increasing demand for fish products in the near future. One of the biggest threats to aquaculture industries and local marine habitats is the transmission of diseases, parasites and nuisance organisms. There has also been growing concern about the use of genetically altered organisms in aquaculture operations, such as use of triploids, transgenics or any selectively bred fish and shellfish. Furthermore, exotic species can destroy the habitats of native marine populations as a result of competition, changing predator-prey dynamics, hybridization, colonization and ecological alterations. -- Within Canada there have been a number of studies directed at the impacts of non- indigenous species on aquaculture production. These studies have illustrated that aquaculture businesses in British Columbia have been more affected by accidental or intentional introductions of aquatic species than the east coast. On the Atlantic coast, relatively few species have been introduced as a result of aquaculture activity, but recent studies have illustrated that many non-indigenous species have entered the region through ship's ballast water and have affected many local aquaculture operations. -- Canada has numerous federal and provincial regulations regarding the introduction or transfer of non-indigenous species, either between provinces or internationally. These management principles are often confusing, operating through both levels of government, and fail to adequately address existing and potential introductions. In order for the country to effectively monitor and control non-indigenous species introduction, existing guidelines will need to be more transparent, flexible and incorporate sound scientific advice with aquaculture management and ballast water controls. Furthermore, Canada should develop appropriate baseline information and assessment methods, improve communication, and evaluate the procedures that have been successful in other countries and apply those measures that would be most suitable