Genetic Engineering and Fish

What is a genetically engineered fish?

Genetically engineered (also called transgenic) fish are those that carry and transmit
one or more copies of a recombinant DNA sequence (i.e., a DNA sequence produced
in a laboratory using in vitro techniques). Because genetic engineering is defined by
the technology that is used to create and transfer the DNA sequence, and not the
source species of the donor DNA, even fish that are engineered with DNA derived
entirely from fish species are considered to be genetically engineered. Currently, no
genetically engineered fish has been approved for food production in the United
States. To date only one company, AquaBounty, has publicly announced that it has
requested FDA approval to market a genetically engineered food animal, a growth-
enhanced Atlantic salmon that is capable of growing 4 to 6 times faster (but not larg-
er) than standard salmon grown under the same conditions.

What are the science-based concerns associated with genetically engineered fish?

The greatest science-based concerns associated with genetically engineered fish are
those related to their inadvertent release or escape. Concerns range from interbreed-
ing with native fish populations to ecosystem effects resulting from heightened com-
petition for food and prey species. There is, in principle, no difference between the
types of concerns associated with the escape of genetically engineered fish and those
related to the escape of fish that differ from native populations in some other way,
such as captively bred populations (Lynch and O’Hely 2001). Ecological risk assess-
ment requires an evaluation of the fitness of the genetically engineered fish relative
to non–genetically engineered fish in the receiving population in order to determine
the probability that the transgene will spread into the native population. Ecological
impacts are the result of the characteristics of the organism, regardless of whether the
organism acquired those characteristics through natural selection, artificial selection,
or genetic engineering. The presence of genetically engineered fish does not a priori
have a negative effect on native populations. If genetically engineered fish are ill-suit-
ed to an environment or are physically unable to survive outside of containment, they
may pose little risk to the native ecosystems. Regulators apply a scientifically derived,
risk-based framework to assess the ecological risks involved with each transgene, spe-
cies, and receiving ecosystem combination on a case-by-case basis. Risks will be quite
specific to the gene, species, and site in question, and simple generalizations concerning
the risks (and benefits) of genetically engineered fish are not scientifically meaningful.

Commercialization of genetically engineered fish will likely depend on the development
of effective containment strategies. If genetically engineered fish are adequately con-
tained, they pose little risk to native populations. The NRC recommended the simulta-
neous use of multiple containment strategies for genetically engineered fish (National
Research Council 2004). Physical containment is an obvious first line of defense to pre-
vent the escape of genetically engineered fish. Examples of such measures may include
building facilities on land or in locations removed from native populations, or ensuring
that water chemistry (temperature, pH, salinity, and concentrations of certain chemi-
cals) is lethal to one or more life stages of the genetically engineered fish, such as treat-
ing effluent water to prevent the release of viable gametes or fry. Biological containment
or bioconfinement approaches such as sterilization are also being developed.