Salmon Fish
The Atlantic salmon fishes are known for their strong, streamlined bodies and their ability to move through steep rivers in fresh and salt waters as their habitat (Jonsson and Jonsson 2). The term “Salmo” is a Latin term which means salmon that originated from the word “salar” which means to leap. The Atlantic salmon are anadromous which means that they spawn in freshwater and acquire most of their food while they explore the marine habitats (Jonsson and Jonsson 2).
The management systems used for production of transgenic Atlantic salmon is similar as those that are being presently used for non-transgenic salmon. In a normal setting, the salmon fishes are hatched using freshwater facilities. It will take at the period of 12 to 18 months for the young salmon to undergo the process of “smoltification” or the stage where they become accustomed to salt water (Jonsson and Jonsson 40). After this process, the salmon fishes can now survive in the marine environment. In a normal setting, breeding of salmon can be done in conventional inland hatcheries. The fertilized eggs are embedded in the bottom of substratum and hatch in spring time. On the other hand, some salmon raisers use genetically engineered substance that contains additional fish growth hormone gene in order to make the Atlantic salmon grow faster. In this process, the brood stock shall be treated to produce 100% genetically female eggs where such eggs are treated to cause reproductive sterility.
These young fish are transformed to “smolts” and will be transferred to sea farms. Normally, the smolts are being contained in sea cages to allow them to grow. These “smolts” can also be grown in net pens, circular tanks and raceways that are situated in the coastal inlets and open ocean. In effect, the all-female offspring are raised in hatcheries at the outset before they are transferred to ocean net pens to mature until harvesting time (Jonsson and Jonsson 4).
Moreau, Conway, and Fleming stated that the breeding system of Atlantic salmon involves two substitute male reproductive phenotypes (737). These shall include the big “anadromous adults” that are undergone migration to sea and have come back to their biological rivers; and the small “precocial parr” which have grown in fresh water and are not yet exposed to salt water (Moreau et al 737). After the small fishes (alevins) have emerged from their nests, they find shelter among the stones on the bottom, in crevices and interstitial holes, tree roots, macro-vegetation in streams and rivers. The availability of slow moving habitats in the stream margin is the critical stage for the survival of the alevins in the first few months (Jonsson and Jonsson 70). The Atlantic salmon typically grows in large streams and rivers. The Atlantic salmon is a sit-and-wait predator and can initiate external feeding before they emerge from the gravel or only about 30% of the yolk is left. Some of the alevins emerge with large amounts of the yolk are still remaining. The diet of a young Atlantic salmon is mostly dominated by small chironomid larvae and pupae as the main food supply for the young fishes during the spring and summer; and during the autumn season, the young fish feed on the larvae of tricoptera and plecotera (Jonsson and Jonsson 82).
References
Jonsson, Bror and Jonsson, Nina. Fish and Fisheries: Ecology of Atlantic Salmon and Brown
Trout. New York, Springer, 2003. Print.
Moreau, Darek T.R., Conway, Corinne, and Fleming, Ian A. “Reproductive performance of
alternative male phenotypes of growth hormone transgenic Atlantic salmon (Salmo
salar)”. Evolutionary Applications 4.6 (2011): 736–748. Print.
