Issues and Methodology for Development of Transgenic Fish for Aquaculture with a Focus on Growth Enhancement

Searching for Solutions in Aquaculture: Charting a Sustainable Course

“…Several gene transfer methods have been tested on fish, but microinjection, whereby a DNA segment is inserted into a fertilized egg, is the most common (see Reference 181 for a review of gene transfer methods and results). Similar to selective breeding, most gene transfer programs have focused on improving commercially important traits (e.g., increasing growth rates, disease resistance, carbohydrate metabolism, and flesh shelf life) (181).…”

“…Cold-water species, such as salmon, appear to respond better to GHs than warmwater species, which grow throughout the year and are likely less sensitive to GH regulation (180). Increases in growth rates are also greater when compared to wild fish than with selected strains (180), indicating that advanced selective breeding programs and GH gene insertion may be modifying similar cellular and physiological mechanisms to increase growth (181).…”

Approaches for delaying sexual maturation in salmon and their possible ecological and ethical implications

“…Genetically modifying salmonids in order to reach a breeding goal could have several unforeseen health and behavioral consequences for the fish (Devlin et al, 2006, Panserat et al, 2014, Leggatt et al, 2012, Devlin et al, 2009a, Devlin et al, 2009b, Sundt-Hansen et al, 2007, Mori et al, 2007, Leggatt et al, 2007, Vandersteen Tymchuk et al, 2005, Bessey et al, 2004) through pleiotropic effects. Detrimental health effects such as skeletal deformations, compromised immune systems and altered organ structures are not compatible with good animal husbandry.…”

Assessing the capacity for compensatory growth in growth‐hormone transgenic coho salmon Oncorhynchus kisutch

“…Rapid growth and improved feed conversion efficiencies are important factors influencing the utility of strains for aquaculture, reducing the cost of production through shortened rearing times and reduced feed costs (Avault, ). The over‐production of growth hormone (GH) as well as domestication and genetic selection can result in very strong enhancements of growth rate in salmonids (Hershberger et al, ; Du et al, ; Devlin et al, , ) and appear to similarly modify physiological pathways (Devlin et al, ; Tymchuk et al ., ). If genetic modification was to be utilized in the future, optimizing growth potential of engineered strains will be important, including exploring the use of compensatory growth approaches to further enhance performance.…”

“…GH‐transgenic salmonids are growing at very high rates, but do respond to nutritional limitations by reducing growth rate. It is unclear whether such fast‐growing fish can be further stimulated by compensatory growth mechanisms, or whether their GH pathways have been saturated through transgenic expression of this hormone (Devlin et al, ; Raven et al, ). To evaluate this capacity, we subjected GH‐transgenic and wild‐type coho salmon Oncorhynchus kisutch (Walbaum 1792) to two periods of food deprivation and re‐feeding and monitored their growth responses.…”