Genetically modified fish (GM) are those fishes whose genetic material is altered through genetic engineering techniques to introduce desired novel traits. The introduced new piece of DNA is known as transgene. Through the introduction of foreign DNA, the fish gains special traits, which makes them superior to the normal ones in having accelerated growth, increased weight, reduced mortality, extreme tolerance to harsh conditions, etc. The DNA/the genetic material used in the genetic engineering process is often spliced from a variety of organisms like mice, bacteria, fish, coral, and even from humans. And the process by which the genetic modifications lead to the evolution of a GM species is brought in through advanced techniques like the microinjection method, electroporation method, etc. Currently, around 35 different species of fishes are being genetically engineered for aquaculture throughout the globe. Among them, the most popular species are trout, catfish, tilapia, flounder, striped bass, and salmon. GM fishes are widely used to produce food, for manufacturing medicines, and many scientific kinds of research.
Advantages of GM Fishes
- Improved Freeze Resistance
Enhanced freeze resistance is one of the major applications of the GM fishes. The resistance can be developed by the insertion of the “anti-freeze gene” from the fishes of the polar region to the normal ones. For eg, Winter flounder are shielded from freezing in ice-laden seawater due to the presence of high concentration of antifreeze proteins(AFP) in their blood. However the Atlantic salmon do not possess any AFP which makes it unfit to survive below -0.7 degree Celsius , affecting the culturing of salmons along the Atlantic coast. Therefore, AFP gene is transferred from flounder to salmon through microinjection for developing the freeze resistance in salmons and they can survive the extreme frigidness.
- Disease Resistant
Through the development of disease-resistant GM fish, the use of antibiotics and vaccines can be reduced to a great extent. The overuse of antibiotics and vaccines contributes to increased antibiotic resistance in pathogens and other side effects to the fish and its consumers.GM fish with disease resistance can find a way to this solve this pressing issue. For instance, the transgenic grass carp have the immunity to fight against Aeromonas hydrophila, which causes hemorrhagic septicemia. And immunity is acquired artificially by mixing the sperm of fish with human lactoferrin (HLF) through electroporation.
- Biomedical Remediation
GM fishes have gained a wider acceptance in the public for the high-value of biomedical applications than food production. Some rare human therapeutic proteins are produced on large scale by using genetically modified fishes as bioreactors. For example, the lines of Tilapia are engineered to produce human clotting factor VII, which is used for liver transplants and injury treatment.
- Improved Growth Rate
When compared to the normal fishes, the genetically modified fishes show a tremendous improvement in growth rate as their growth hormone expressions are modified. The characteristic of the growth rate in GM fishes received the greatest attention since it has a considerable significance in the field of aquaculture. Almost two to threefold increase has been reported in Tilapia, Atlantic salmon, and common carp as compared to non-GM fishes.
- Modification In Metabolism
Metabolism modification in fishes can reduce the food conversion ratio (FCR). FCR = amount of feed/weight gain. When the FCR value is low, higher will be the weight gained. If the FCR value can be reduced, more weight can be produced from less feed. For instance, some species require wild-caught pelagic fish to manufacture their feed. If the metabolism of carbohydrates can be improved, the species can be fed with foods with land origin such as soybean meal, vegetable oil, etc.
Disadvantages of GM Fish
- The concern of GM escape
GM fish in an open system is capable of escaping to the population of wild species. These escaping may cause genetic pollution by the interbreeding of GM species with wild ones. (eg GIFT Tilapia).In addition to genetic pollution, the escape of GM fish depletes biodiversity by competing with the wild population. As the GM fishes are more active, the wild ones face difficulties in surviving. Even the highly aggressive nature of GM on feeding leads to more exposure to predation. However, they only remedy to protect the natural population from these modified ones are by culturing GM in closed aquaculture systems.
- Human health issues
As the genetically modified fishes are more resistant to environmental toxins, it entails the assemblage of toxins to the consumer level. There is also a distrust about the growth hormone in fishes which may cause harm to humans. Besides these impacts, some proteins produced by GM fishes may also be toxic to the human while it is beneficial to themselves. So several testing must be conducted to make sure that the proteins won’t affect human health and many studies show that GM fish must be treated with more caution.
- Public acceptance
Even though a bunch of people accepts the GM products, there is still a majority of consumers who have ethical and safety concerns about the proper use of organisms. The people are also distressed about the unnatural process of insertion of genetic material with human interference. However, public opinion is perpetual as the artificial insemination, in-vitro fertilization, etc are globally accepted.
The genetically modified fishes have many beneficial applications in the field of medicines, food production, etc. More research should be done in this area for public acceptance of GM fishes. It is better to include fish DNA material rather than the genes from mammals, bacteria, or viruses. Advanced researches are mandatory to ensure the safety of genetically modified fishes. Moreover, GM food will become essential to meet the need of the promptly growing population of our world.
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