Salmons is the most accurate species for genetic engineering because it has a greater consumer demand in the aquaculture industry. Moreover, the percentage of the wild population of normal salmons is pathetically depleting due to environmental pollution, habitat degradation, overfishing, etc. The aquaculture of salmons is in a well-developed manner in almost all temperate countries of the world. Among the salmon species, Atlantic salmon is the most reared species due to its higher production capacity. These species can adapt easily to the culturing conditions and even can adapt to the culturing conditions out of their normal conditions. In the US, genetically engineered Atlantic salmon is the first GE organism that has been approved for human consumption. The genetically modified salmons contribute a lot of benefits to the industry of aquaculture. Through captivity, rather than from the wild salmons, these salmons are able to produce numerously in containments that are closed to land and population. Moreover, culturing salmons in a closed system can reduce the transport cost and helps to improve the supply chain of the fish. Additionally, it also supports the wild salmon species by reducing the pressure of fishing. Overfishing is resulting in the decline of many salmon species, so genetically modified salmons will be very beneficial in those cases and also aquaculture can provide a fresh supply of salmons for the growing population throughout the year.
The GE salmon can grow up to market size within a half time when compared to the normal Atlantic salmon. Farmed salmon takes 30 months to reach an adult size where GE Atlantic salmon takes only 18 months to become an adult. By being an anadromous species, it spends its juvenile phase of the life cycle in freshwater and migrates to the sea for spending the rest of the period of life cycle until spawning. At the time of spawning, the salmons return to the freshwater and spawn on the currents of the shallow cold freshwater. The eggs are released into the river bed by the females and males release sperm over the eggs. Thus, fertilization occurs normally in salmons. The main issue of the normal salmon fish is the decelerated growth, as it can only grow to a size of 20-30 grams in the first year of its life cycle. It can be solved by the introduction of genetically engineered salmon species. But, there exist a chance of escaping GE salmons to the wild population of normal salmons and can become a threat to the native salmons by predation or through competition for food and space. Genetic contamination is another great concern in the case of GE salmons because it is impossible or difficult to eliminate the effects of genetic contamination,
The genetically modified salmons were created from a growth hormone gene from a species of Chinook salmon and a gene promoter from an ocean pout. The transgene from these two species was microinjected to the fertilized eggs of targeted salmon species. The presence of introduced transgene is detected using polymerase chain reaction (PCR) with the use of specific oligonucleotide primers. The newly produces GE salmon possess almost 99.9998% of gene constituent of original Atlantic salmon and only a genome of 2.97 billion bases were found additionally. This shows that the 95 % proteins of growth hormones from Atlantic and
Chinook salmons are identical and the promoter from the ocean pout is the only new element in GE salmon. These promoters were chosen because the genes controlled by these promoters are capable of expressing continuously. In contrast, the promoter for growth hormone in normal salmon is expressed only under certain environmental conditions. With the introduction of this transgene, genetically modified salmon can grow faster than conventional salmons with less amount of feed. The GE salmon only required less amount feed as compared to normal salmon to produce the same size fish.
The GE salmon can indeed grow faster than normal salmons and can bring more productivity and profitability. Even though the genetically improved salmons and the unaltered farmed salmon have the same nutritional difference in comparison with the wild salmon. But some nutritional factors are different in genetically modified salmon which is capable of causing cancers. Despite the sterile salmons, some fertile salmons can also be found after genetic engineering and can cause genetic contamination or genetic pollution among the wild population through escaping. Since the transfer of genetic material from one organism to the
other is not a normal process, some consumers claim that it can cause a lot of unpredictable effects on human health and the ecosystem as it is not a natural process. So, more researches and studies are needed to reduce their impact on the environment and organisms.
- Du, Shao Jun, et al. “Growth enhancement in transgenic Atlantic salmon by the use of an “all fish” chimeric growth hormone gene construct.” Bio/technology 10.2 (1992): 176-181.
- Male, Rune, et al. “Biotechnology in aquaculture, with special reference to transgenic salmon.” Biotechnology and Genetic Engineering Reviews 11.1 (1993): 33-56.
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