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Genetically Engineered Fish: Swimming Against the Tide of
Reason -
vedi:
OGM
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OGM Bocciati
A report written
by Dr. Jan van Aken for Greenpeace International, January 2000
This briefing
examines the development of genetically engineered (GE) fish, which could soon be produced
on a commercial scale.
It concludes that the physical containment of these fish cannot be
guaranteed and any escapes into the environment could have devastating effects on wild
fish populations and biodiversity.
Introduction
Although GE fish for food purposes is not yet on the market, the first products could be
ready for commercialisation by the year 2002 if regulatory approval is
granted. Since the
development of the first GE fish in the early 1990s (1), laboratory researchers and
aquaculture companies have concentrated on genetically engineering fish that would grow
faster and need less feed. Many research groups have successfully introduced growth
hormone genes from human or animal sources into several fish species such as
salmon, carp, trout, medaka and tilapia, causing them to grow several times faster than their natural
counterparts.
Environmental
risks
Genetically
engineering fish is a high risk technology with potentially disastrous consequences if the
GE fish escape into the environment. Fish species used in aquaculture are very similar to
wild fish and may survive and reproduce in the natural environment (2) and readily crossbreed with
their wild relatives.
Whenever a newly introduced gene enhances the mating success of a GE fish while at the
same time decreasing the viability of the offspring, a few GE fish could ultimately cause
the extinction of healthy, wild populations. This has recently been verified by
researchers at the Purdue University in the USA who discovered that even a small number of
growth-enhanced GE fish could eradicate a large population of wild fish (3). Stressing that body size
is an important trait for mating success in many fish species, the researchers used
computer models based on experimental research and revealed that, due to the mating
advantage of growth-enhanced GE fish, the genetically engineered trait will be transferred
to the natural population, but reduced offspring viability means that this "Trojan
gene" will eventually lead to extinction.
There are other scenarios that highlight the global risks associated with the escape of GE
fish into the environment. Since enhancing their growth rate increases their daily feed
requirements, this could have a devastating effect on the natural
environment, especially
as most fish that are currently being engineered - e.g. salmon, trout, carp and tilapia -
are predators. Past experience has shown that introducing large predatory species into new
environments can lead to ecological disasters. In the 1960s, for instance, the Nile perch
was introduced into Lake Victoria in Africa and, within a decade, the local population of
over 400 different smaller fish species declined from 80% to 2% of the lake’s total
fish stocks. Probably 50% of the native species disappeared from Lake Victoria because
they were not able to cope with the new invader exhibiting its insatiable
hunger. Similarly, the release of a growth (and hunger) enhanced salmon or carp into a natural
environment could load a heavy burden on the native fish populations. Such fears have
recently been fuelled by the findings of Canadian researchers who discovered that GE coho
salmon were far more aggressive than natural salmon.(4)
Another trait that is currently being investigated by genetic engineers is tolerance to
cold temperatures. This would enable GE fish to survive in areas from which they were
previously excluded and compete with native species, therefore adding to the existing
global problem in aquatic ecosystems caused by exotic invaders such as zebra mussels in
the Great Lakes.
In view of the
potential for serious harm to arise, research into the possible effects of GE fish
escaping into the environment is urgently needed and extreme caution should be exercised
before considering any commercialisation approvals.
Inadequate safety
measures
Some companies and
researchers that are involved in the production of GE fish claim that the commercial use
of their products would not harm the environment since the fish could be contained in
land-based water tanks. They further argue that the GE fish could be sterilised and thus
be unable to crossbreed with natural populations even if they were to escape into the
environment. However, none of the safety measures that have so far been developed are
adequate to safely contain GE fish and prevent accidental releases.
Any open sea
cultivation will lead to escapes, mistakes will happen, and there will be an economic
incentive to circumvent safety measures.
Landlocked
systems:
Once the
production of GE fish becomes commercialised, it will be impossible to control the
whereabouts of every single individual and assure compliance with appropriate containment
measures. This lesson can be learned from experiences with GE crops, where mistakes have
occurred and unapproved varieties have been illegally planted in several countries (5). Mistakes will also be made
in the case of GE fish with batches being accidentally mixed and GE fish finding their way
into open water. As GE fish are intended for use on a global scale, a reliable containment
regime following commercialisation is just not conceivable.
Furthermore, landlocked systems need specific safety measures to avoid accidental releases
into the environment.
Recently, the Environmental Risk Management Authority in New Zealand
identified flaws in the safety system of the GE salmon tanks of the private company King
Salmon where GE salmon eggs could have come into contact with sperm before escaping into
the environment.(6)
Although there is no evidence that such an escape has yet occurred, this example
highlights the difficulties in designing safety measures which are 100%
effective.
In
addition,
land-based water tanks with appropriate security measures (e.g. water
sterilisation) are
not cost effective and large scale aquaculture in sea pens is much more
economical. Consequently, there will be a strong financial incentive for unscrupulous operators to put
GE fish in sea pens. Experience with traditional aquaculture shows that any cultivation in
the open sea cannot entirely prevent the escape of cultivated fish, however strong the net
pens might be. In 1988, for instance, a storm tore apart the moorings and nets of hundreds
of sea pens along the Norwegian coast, allowing a million farmed salmon to
escape. No
economically viable open sea system could cope with all - sometimes extreme -
environmental conditions.
Sterilisation:
If all GE fish were sterile, those which escaped into the environment could neither
transfer their genes into wild populations nor establish themselves in natural
habitats. However, there are currently no techniques available that are able to guarantee 100%
sterilisation of the target fish. The most common sterilisation technique involves
manipulating the number of chromosome sets. While natural lines have two chromosome sets
(diploid), fish with three chromosome sets (triploid) are sterile. Triploidisation of
fish, e.g. through pressure-shocking fish eggs, is possible but it is not reliable enough
to be used as a containment measure for GE fish since, with the current
procedures, a
certain percentage of the treated fish remains fertile.(7)
In order to be fully effective as a containment measure, sterilisation must ensure that
every single GE fish is, and remains, sterile under all environmental
conditions. A 99%
reliability is not enough since, as the researchers at Purdue University
concluded, even a
single fertile GE fish could be sufficient to destroy a local population under certain
circumstances.
In the late 1980s,
the companies involved in developing GE crops insisted that their products would be safely
contained during field tests and that no contamination of the environment would
occur.
Several years later, when the first GE crops were commercialised, it became evident that
any commercial use would mean unrestricted releases into the environment. It can be
anticipated that the same will be true for GE fish.
Approaching
commercialisation
Although traits
such as cold tolerance, disease resistance and pollution detection are also being
investigated, the majority of research and development work on GE fish is currently
focused on growth enhancement and is being carried out in several countries around the
world (e.g. in the USA (8,9), Canada (10), New Zealand (11), Israel (12), Thailand (13), Taiwan (14), the UK (15) and China (16)).
The race to
commercialise growth enhanced GE fish is currently being led by the Massachusetts-based
US/Canadian company, A/F Protein Inc., which has engineered a growth enhanced Atlantic
salmon containing a growth hormone gene from chinook salmon. This "AquAdvantage
salmon", as it is called, grows 4 to 6 time faster than ordinary salmon and A/F also
claims that it has a higher food conversion ratio and thus needs 25% less feed over the
entire life cycle. (17)
Nearly 100,000 GE
salmon and trout are already swimming in several hundred fibreglass tanks belonging to the
A/F subsidiary, Aqua Bounty Farms, in the Canadian provinces of Prince Edward
Island,
Newfoundland and New Brunswick (18).
The first eggs for
commercial breeding could be available in 2000 and the first transgenic fish could be in
the supermarkets from 2002. A/F Protein is waiting for regulatory approval in the USA,
Canada and Chile (19)
although no formal regulation appears to exist in the two latter countries. It has also
licensed the ‘super salmon’ to fish-breeders in Scotland and New
Zealand.(20) A/F Protein has used the
same technology to design growth enhanced flounder, trout, arctic char and
tilapia. (19)
Other companies
are also involved in the drive to commercialise GE fish and Kent SeaFarms in San Diego,
USA, are working with a $1.8 million grant from the US Department of Commerce to develop
GE fish that grow quicker, require less feed and are more disease resistant. (21) Elsewhere in the world,
King Salmon - the largest salmon producer in New Zealand - is known to be performing
trials with growth enhanced GE salmon that also contains a gene from chinook salmon (22). In Cuba, a biologist
from the Centro de Ingenieria Genetica y Biotecnologia recently told a German newspaper
that they have already produced 30 tons of growth enhanced tilapia and that they are
awaiting approval for commercial use in Cuba.(23)
It remains to be seen how the fish farming community will react to GE fish. According to a
recent news report, the International Salmon Growers Association voted overwhelmingly in
1998 to shun GE fish (19)
and representatives of the US aquaculture community have been somewhat negative. This is
perhaps not surprising since salmon is already in such worldwide overabundance that the
wholesale price has sunk to $2 a pound from $6 in the last ten years.
Greenpeace demands
- Genetic engineering of fish for commercial purposes should be prohibited, as should all
associated research. Once approved for commercial use, GE fish may never be
contained.
- Until this happens, each sovereign nation must take full responsibility for all
research,
development and releases of GE fish. Fish obey no boundaries and any releases into the
environment must necessarily be considered as global releases
- The Biosafety Protocol to the Convention on Biological Diversity should apply to all GE
organisms, including those destined for contained use so that GE fish are subject to
international controls.
- Each sovereign nation which imports GE fish must decide whether containment measures
recommended by exporting nations provide adequate protection for the importing
nation’s biodiversity. This should not be decided by the exporter or exporting
nation.
References:
(1)
Du S
et al. (1992), BioTechnology 10:176-181
(2) News Release,
Minnesota Sea Grant Media Center, Safeguards proposed for genetically altered
fish,
www.seagrantnews.org/news/minnesota.html
(3) Muir WM, Howard RD (1999) Possible ecological
risks of transgenic organism release when transgenes affect mating success: sexual
selection and the Trojan gene hypothesis. PNAS 96:13853-13856
(4) National Post, September 4 1999, pB12:
‘Frankenfish or salmon saviour ?’ by Sarah Schmidt
(5) In 1997, Monsanto mistakenly sold unapproved GE canola (oilseed rape) varieties in
Canada and had to recall some 60,000 bags (enough for sowing 600,000 acres). Some fields
where the unapproved varieties had already been sown had to be ploughed up. (The Western
Producer, April 24 1997: Canola seed recalled because of genetic
contamination; Reuters
newswire April 17, 1997). In 1998, a test batch of Monsanto GE sugar beets was mistakenly
sent to a Dutch refiner and mixed with normal sugar (Reuters newswire Dec. 3, 1998)
(6) The Dominion, Nov. 25, 1999: Concern at genetic salmon egg escape.
(7) Shelton WL, Reproductive manipulation of fishes: ecologically safe assessment of
introductions.US-ARS, Biotechnology Risk Assessment Research Grants, Program Abstract of
Funded Research 1996.
(8)
www.ag.auburn.edu/dept/faa/facil6.html
(9)
http://vm.uconn.edu
(10) Devlin RH et al. (1994) Extraordinary salmon growth. Nature 371:209-210
(11) Dr. Frank Sin at the University of Canterbury,
www.canterbury.ac.nz./publish/research/97/A19.htm
(12) Benzion Cavari at Hebrew University, Jerusalem,
http://ocean.org.il/nio/staff/3.htm
(13) At the Aquatic Resources Research Institute of the Chulalongkorn University,
www.chula.ac.th
(14) At the Division of Cellular and Molecular Zoology of the Academia
Sinica, www.sinica.edu.tw
(15) E.g. by Prof. Norman Maclean of Southampton University, according to
Times, May 26
1997: Gene-modified fish grow three times faster than normal
(16) Wu Chingjiang (1990) at the 3. Int. Symposium on genetics in
aquaculture, Trondheim,
June 20-24 1988 (in: Gjedrem T (ed) 1990, Genetics in Aquaculture III, Aquaculture vol.
85, pp 61-68)
(17)
http://webhost.avint.net/afprotein/bounty.html;
see also: Under the microscope: We can
build super fish, but should we?, by Dan McGovern, May 1999,
www.biotech-info.net/super_fish.html
(18)
http://webhost.avint.net/afprotein/news.html
(19) Christian Science Monitor: Designer fish flounder over legal hurdles.
www.csmonitor.com/durable/1999/03/04/text/p19s1.html
(20) The Vancouver Sun, March 3, 1997
(21) Under the microscope: We can build super fish, but should we?, by Dan
McGovern, May
1999,
www.biotech-info.net/super_fish.html
(22) AFP newswire April 6, 1999: Genetically manipulated salmon exposed in New Zealand
(23) Der Spiegel, July 5 1999, page 188
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