Genetic engineering processes are becoming increasingly common
and are being applied to a widening variety of organisms. Genetic
modification involves identifying genes scientists hope will express
the desired traits when introduced into fish. These new genes can
come from other species of animals, plants, bacterium, and even
There are several processes used to insert “new” DNA
into fish, ranging from inserting genetic material directly into
eggs to subjecting fish eggs to electrical pulses, which form pores
and allow foreign DNA to access the eggs. The precise location where
the new genetic material has attached to the original DNA is unknown
and may vary between individual fish so scientists need to check
to ensure the inserted gene is present and determine if it functions
as expected. Once scientists have determined that the genes have
been inserted, the fish are raised like other farmed fish.
Although this discussion is focused on transgenic fish, other transgenic
aquatic organisms, including marine and freshwater plants and shellfish,
are being fast-tracked for commercialization.
Genetic engineering technology is being applied with more frequency.
These increasingly common practices, coupled with a lack of safeguards
and regulations, make state action crucial to protect public and
Risks Associated with Transgenic Fish
Food Safety Issues
Potential human consumption of transgenic fish and shellfish raises
an assortment of food safety concerns.
- Genes inserted to promote disease resistance may cause transgenic
fish to absorb toxic substances (like mercury) at a higher rate(1)
and pass these toxic substances on to consumers.
- Roughly 90 percent of food allergies can be attributed to consumption
of eggs, fish, shellfish, milk, peanuts, soybeans, tree nuts,
and wheat.(2) If proteins used in the
production of transgenic species originate from one of these eight
sources, there may be potential for allergic reactions among consumers.
- The majority of transgenic fish have been inserted with growth
genes.(2) Large doses of growth hormones
may pose health risks if consumed in raw and uncooked foods like
Transgenic fish pose potential threats to natural ecosystems and
native species populations that are not fully understood and remain
insufficiently studied. However, it is known that:
- Fifty percent of all intentionally introduced fish have had
harmful economic or environmental effects(3);
- Sixty-six percent of all unintentionally introduced fish have
had harmful economic or environmental effects(3);
- Millions of farmed fish escape from open water facilities each
year and contaminate native populations(4);
- It is inevitable that transgenic fish will escape from aquaculture
pens or field trial parameters.(3)
Although these statistics reflect impacts from the releases of
non-transgenic fish, the implication is clear – introduction
of foreign species to an ecosystem does not occur without negative
consequences. The environmental risks of releasing transgenic fish
may threaten biodiversity in natural ecosystems and the genetic
integrity of those systems.
Genetic alterations in transgenic fish may give them competitive
advantages over native species.
- By using growth hormone genes, researchers have been able to
increase growth rates 2 to 11 times faster than the normal rate.(5)
Faster development leads to earlier sexual maturity and potentially
more breeding opportunities than their native counterparts.
- If transgenic fish are genetically enabled to breed earlier
and at a faster rate, transgenic genes are more likely to be spread
throughout native populations. This would reduce the genetic diversity
of the native population.
- Research indicates that transgenic fish may reach maturity faster,
but they also die sooner.(6) This “Trojan
gene” scenario could have devastating consequences if transgenic
fish interbreed with native populations. Additionally, if transgenic
genes for rapid growth are correlated with shorter life expectancy,
the overall life expectancy for the entire population may be reduced.(6)
- Transgenic fish may have similar effects on natural ecosystems
as exotic species. An increased growth rate is often accompanied
by a voracious appetite, and transgenic fish may out-compete native
species for resources, destroy plants and sensitive habitat, and/or
alter the food chain in an ecosystem.
For more information on invasive species see SERC’s package
the Spread of Invasive Species.
Dozens of genetically engineered fish and shellfish projects are
currently underway throughout the world. Genetic engineering is
altering the genetics of a variety of species for the purposes of
increasing aquaculture production, medical and other research, cleaning
up water pollutants, and ornamental reasons. Examples of projects
- Inserting genes for increased growth rates and increased resistance
to disease in Rainbow trout, tilapia, catfish, grass carp, mollusks,
and prawns. These genetic modifications are intended to increase
aquaculture productivity for human food consumption.
- Inserting human clotting genes into Tilapia for possible pharmaceutical
- Inserting the “anti-freeze” gene into goldfish for
research purposes and to add consumer appeal as household pets.
- Algae are being genetically engineered for use as a bioremediation
tool. Genetic modification is increasing the algae’s ability
to absorb higher levels of toxic heavy metals.(5)
For a list of various aquatic transgenic species projects, visit
Initiative on Food and Biotechnology.
States Can Lead the Way
Although there are no federal regulations for transgenic fish,
states can protect the health of their citizens and environment.
Many states have existing policies in place that could be modified
to regulate transgenic fish:
- Fifteen states have adopted regulations concerning uncontained
uses of transgenic fish and other transgenic marine organisms.(2)
- California requires permits for genetically engineered species.
One year after its enactment, the state had issued fourteen permits,
mostly to universities and research institutes.(7)
- Five states have specifically defined genetically engineered
organisms as exotic species.(3)
- The Chesapeake Bay Program – a partnership consisting
of five states, the District of Columbia, and the Environmental
Protection Agency – defines genetically engineered organisms
as exotic species.
- The National Institute of Health created research guidelines
for genetic engineering. Some states (and some townships within
states) adapted their statutes to control genetic research within
- States could include permit requirements for transgenic fish
within existing aquaculture regulations.
- States could include permit requirements for transgenic fish
within their Coastal Management Plan.
(1) “Future Fish: Issues in Science and Regulation of Transgenic
Fish.” Washington, D.C.: Pew Initiative on Food and Biotechnology,
January 2003. 9 February 2005 <http://pewagbiotech.org/research/fish/>.
(2) Hallerman, Eric M. “Genetically Modified Fish and Shellfish:
Food for Thought.” Virginia Issues and
Answers 8.1 (Winter 2002). Virginia Tech Publications &
Outreach Communications. 9 February 2005 <http://www.via.vt.edu/winter02/article2.pdf>.
(3) Stenquist, Susan. “Federal and State Regulations Relevant
to Uncontained Applications of Genetically Engineered Marine Organisms.”
In: Zilinskas, Raymond A. and Peter J. Balint-Kurti, eds. “Genetically
Engineered Marine Organisms: Environmental and Economic Risks and
Benefits.” Amsterdam: Kluwer Academic Publishers, September
(4) Lurie, Karen. “Trojan Gene.” 1 April 2004. ScienCentral
News. 9 February 2005 <http://www.sciencentral.com/articles/view.php3?language=english&type=24119&article_id=
(5) “A Look at the Science: How Transgenic Fish Are Created
and Examples of Current Research.” Washington, D.C.: Pew Initiative
on Food and Biotechnology, January 2003. 9 February 2005 <http://pewagbiotech.org/research/fish/trifold.pdf>.
(6) Muir, W.M. and R.D. Howard. “Fitness Components and Ecological
Risk of Transgenic Release: A Model Using Japanese Medaka (Oryzias
latipes).” American Naturalist
158.1 (July 2001). Virginia Tech, Information Systems for Biotechnology.
9 February 2005 <http://www.isb.vt.edu/nfca/library/Muir_howard_amnat.pdf>.
(7) “State issues 14 permits, rejects one for genetically engineered
species.” Associated Press. 30
August 2004. Contra Costa Times.com. 9 February 2005 <http://www.contracostatimes.com/mld/cctimes/living/science/9534274.htm?1c>.