Massachusetts Aquaculture White Paper - Genetics and Exotics

Cultured fish commonly represent genetically exogenous populations or crosses between them. In addition, the genetic makeup of cultured populations has frequently been altered as the result of inbreeding, selective breeding, or domestication. Biotechnologies are also now making it possible to genetically manipulate aquatic organisms to promote economic advantages through increased growth rates so that aquaculture food production is more efficient and profitable. For example, researchers at Fisheries and Oceans Canada in West Vancouver have altered the DNA of Pacific Salmon to create fish that are on average, more than 11 times larger than their natural counterparts (Vames 1995). Thus, cultured fish can represent distinct gene pools and their escape or intentional release into the wild could adversely impact natural populations.

For instance, the Division of Fisheries and Wildlife, in partnership with other state and federal agencies and the private sector, have been working for over 20 years to restore Atlantic salmon to southern New England. These fish are now returning in the low hundreds to the Connecticut and Merrimack Rivers. In contrast, the numbers of pen-reared Atlantic salmon in Maine far outnumber wild fish returning to Massachusetts, to all of New England and in the entire North Atlantic combined. With so few salmon returning to the rivers, any "catastrophic event" causing a massive release of pen-reared salmon could result in a significant degree of genetic contamination to those wild stocks. Even a "slow trickle" of pen-reared fish escaping could have a negative impact over time on natural salmon populations.

The escape or release of exotic fish species and other aquatic organisms cultured for food, management or recreation can also have serious ecological consequences for native flora and fauna. Besides the possible genetic implications, impacts resulting from escaped or intentionally released aquatic species may include habitat, trophic, and distributional alterations as well as the introduction of parasites and diseases.

Regulations are important to safeguard wild populations from escaped, released or exotic aquaculture species. The Division of Fisheries and Wildlife's new aquaculture regulations address the issue of exotics in the permitting process. Species permitted to be cultured are based on the type of facility (closed vs. open system), the location of the facility, and the species found in the watershed.

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Published: September 1995