Predator Avoidance of Transgenic Channel Catfish Containing Salmonid Growth Hormone Genes

Abstract

Transgenic channel catfish (Ictalurus punctatus) containing salmonid growth hormone genes can grow 33% faster than normal channel catfish under aquaculture conditions. However, before transgenic catfish are released and utilized by the private sector, their genetic impact on the natural environment must be examined. Predator avoidance is one of the major fitness traits determining potential environmental risk. To determine the predator avoidance ability and growth performance of transgenic catfish in a natural habitat, various densities of transgenic and nontransgenic channel catfish were communally stocked in 0.04-ha earthen ponds without supplemental feeding. Largemouth bass (Micropterus salmoides) and green sunfish (Lepomis cyanellus) were stocked as predators. Nontransgenic fry had better predator avoidance than transgenic channel catfish when data were pooled (p <.01). When data were not pooled, nontransgenic catfish had better predator avoidance in six trials and transgenic individuals had better predator avoidance in four trials. There was no difference in predator avoidance in three trials. Overall predator avoidance was also better for nontransgenic individuals (p <.01) when the fish were evaluated as 3.5-g fingerlings, more clearly than as fry, as transgenic individuals were more vulnerable in 3 of 4 trials at this life stage. There was no significant difference in growth performance between transgenic and nontransgenic channel catfish in ponds without supplemental feeding. These findings indicate that transgenic channel catfish could be used for commercial aquaculture without affecting the natural environment. Although transgenic channel catfish may be released to nature by accident, any ecological effect would be unlikely because the increased susceptibility of transgenic channel catfish to predators would most likely decrease or eliminate the transgenic genotype.

Integration mechanisms of transgenes and population fitness of GH transgenic fish

“…They suggested that any ecological effect would be unlikely because the increased susceptibility of transgenic channel catfish to predators would most likely decrease or eliminate the transgenic genotype if they were to be released into nature [24]. Similar results were also found in a study by Abrahams and Sutterlin [25].…”

“…Dunham et al studied the predator avoidance of GH transgenic channel catfish (Ictalurus punctatus) and found that overall predator avoidance was also better for non-transgenic individuals [24]. They suggested that any ecological effect would be unlikely because the increased susceptibility of transgenic channel catfish to predators would most likely decrease or eliminate the transgenic genotype if they were to be released into nature [24].…”

Increased food intake in growth hormone-transgenic common carp (Cyprinus carpio L.) may be mediated by upregulating Agouti-related protein (AgRP)

“…(Martinez et al, 1999;Rahman et al, 1998) and common carp (Cyprinus carpio L.) (Wang et al, 2001;Zhong et al, 2012). During recent years, it has become clear that elevated growth hormone (GH) levels in transgenic fish induce a wide range of effects apart from growth promotion (Devlin et al, 1994;Du et al, 1992;Martinez et al, 1996;Nam et al, 2001;Rahman et al, 1998;Wang et al, 2001;Zhong et al, 2012), including altered metabolism (Guan et al, 2008;McKenzie et al, 2003;Stevens et al, 1998), swimming performance (Farrell et al, 1997;Lee et al, 2003;Stevens et al, 1998), anti-predator behavior (Abrahams and Sutterlin, 1999;Duan et al, 2010;Dunham et al, 1999) and growth-related neuroendocrine regulation (Raven et al, 2008). In addition, GH treatment resulted in increased food intake and feeding behavior in normal fish (Johnsson and Bjornsson, 1994).…”

Gene–environment interactions influence ecological consequences of transgenic animals

“…This concern has led to numerous articles on the conceptual problem of ecological risk-assessment (8)(9)(10), and several laboratory and theoretical studies have addressed the fitness and/or ecological consequences of transgenic animals (11)(12)(13)(14)(15)(16)(17). However, except for a few field trials on nematodes and mites, few empirical studies to evaluate the direct ecological effects of transgenic animals in more natural environments have been undertaken (18,19).…”