Marine GEOs: Products in the Pipeline

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Hotlink 1 (Marine GEOs: Products in the Pipeline). Genetic engineering expands the range of traits that aquatic organisms can exhibit beyond the limitations of traditional breeding. Genetic engineering can:

• Introduce genes that produce a compound not found in the unmodified species. For example, researchers have introduced genes that lead to secretion of antifreeze protein in goldfish, human clotting factor VII in tilapia, and cecropin, an antimicrobial agent, in catfish.
• Produce greater changes in a trait by introducing genes that alter the season, life stage, body tissues, or level of production of a compound, that is identical or very similar to one in the unmodified species. For example, the accelerated growth of some genetically modified Atlantic salmon and tilapia is driven by a foreign promotor--a DNA sequence that overrides the fish's normal control over the secretion of growth hormone (MacLean and Laight 2000). The introduced promoter derived from the ocean pout, a fish that lives in Arctic waters, directs year-round secretion of antifreeze protein. This promoter makes the genetically modified fish secrete growth hormone in its liver rather than in its pituitary gland, leading to a greater effect of the hormone on muscle growth (Hew et al. 1995; Hew and Fletcher 1996). In salmon, this strong promoter overrides normal controls and directs secretion of growth hormone during the winter when waters are cold, a part of the year when unmodified salmon would produce little or no growth hormone (Devlin et al. 1994).
  
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Hotlink 2 (Marine GEOs: Products in the Pipeline). Many fish and shellfish species have traits that come close to the advantages offered by some crop plants--they produce large numbers of eggs (from tens to millions). This gives researchers more and cheaper opportunities to introduce genes and work out various logistical problems. Another advantage is that the eggs and sperm of most fish and some shellfish are easy to manipulate outside the animal's body. Finally, some fish and shellfish species reach sexual maturity by age 1 or younger, so that biotechnologists can propagate many generations and screen descendants to select best performers.

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Hotlink 3 (Marine GEOs: Products in the Pipeline). Researchers are developing methods to engineer algae (Kloareg et al. 1999, Minocha 1999). A number of possible targets for getting engineered genes into algae include spores involved in reproduction; gametophytes--fine filaments of this reproductive part; tissue explants; and protoplasts--artificially isolated cells that lack a cell wall. A protoplast's lack of a cell wall makes it easier to deliver novel DNA into the its nucleus. Researchers are also advancing methods to regenerate whole adult algae from tissue explants and protoplasts, making it possible to propagate whole genetically engineered algae from these genetically engineered parts.

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Hotlink 4 (Marine GEOs: Products in the Pipeline). Consumer attitudes towards different kinds of marine GEOs have not been adequately assessed. Recent opinion polls suggest that U.S. consumers are nervous about eating genetically engineered salmon (Pew Initiative on Food and Biotechnology 2001). Probably related to this consumer concern, various salmon farming industry associations have stated they are not interested in producing genetically engineered salmon at this time:

B.C. Salmon Farmers Association--Issued March 1, 2000: The Board of Directors, at a meeting on February 24, 2000, voted unanimously to strengthen its policy against the use of transgenic fish in British Columbia. Membership in the BCSFA is contingent upon companies using only naturally bred salmon for food production in their operations. "B.C. salmon farmers are wholly opposed to the use of genetically modified fish in aquaculture--both here in British Columbia and around the world," said BCSFA Executive Director Anne McMullin. "Transgenic fish are not used in commercial production today, and should not be used in the future unless science can prove that they present no danger to human health, wild stocks or the marine environment."

Canadian Aquaculture Industry Alliance--Issued August 6, 2000: reaffirmed its position against the use of transgenic salmon in aquaculture; and Executive Director added, "Our farmers do not and will not support the use of transgenic fish until they can be shown to be safe for the consumers and the environment."

International Salmon Farmers Association--Policy statement adopted at its 23rd General Meeting in 1999: RESOLVED to reconfirm the policy adopted at the Seventeenth General Meeting of the Association: "In accordance with sound environmental practice, the ISFA firmly rejects transgenic salmon production."

Scottish Quality Salmon--Statement published in IntraFish April 18, 2000: [T]he association, which promotes Scottish farmed salmon, says its members remain "totally opposed to the use and marketing of any such products [transgenic salmon]."

Washington Fish Growers Association--Official policy statement of 2000: "Transgenic fish (as defined by actual transfer of genes from one specie to another specie) are not used in commercial production in Washington state today and should not be used here or elsewhere in the future unless they are proven to be healthy and nutritious, safe for human consumption and of minimal risk to the environment. This would mean approval by appropriate state and federal agencies."

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Hotlink 5 (Marine GEOs: Products in the Pipeline). Land-based recirculating systems include a waste-treatment component that treats the wastewater and then returns the treated, clean water to the fish production tanks. Less than 10% of the water is discharged from the facility as well treated effluent, sometimes into constructed ponds where it can be further processed. Recirculating systems that use biological filters to purify water before it is recirculated to fish tanks generate a particulate, organic sludge waste, which is suitable as environmentally sound crop fertilizer. See illustrations below.

B. Cross-sectional sideview of escape barriers in effluent path of recirculating water aquaculture system.

C. Photograph of stainless steel wedgewire screen. The recirculating system shown in figure B above contains two of these screens. The screens act as the final barrier for effluent from fish rearing tanks (see figure A above). There is a 1mm gap between the stainless steel wedgewires (Swiss army knife shown for scale). Effluent from incubators of tanks holding fish smaller than a total length of 2 cm must first pass through a sock filter trap (not shown). Effluent from units holding fish at or above a total length of 2 cm (equivalent to a head diameter of 2mm) goes directly to these wedgewire screens.

Indoor recirculating facility housed in a greenhouse in Louisiana. Photo used with permission of Dr. Jimmy Avery, Mississippi State University.

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