Sustained predation effects of hatchery‐reared transgenic coho salmon Oncorhynchus kisutch in semi‐natural environments

Abstract

Summary1. The potential risks of accidental or intentional introduction of transgenic organisms to nature are unknown. We have previously shown that, after being reared in the hatchery, growth hormone transgenic coho salmon Oncorhynchus kisutch can exert a stronger predation effect on natural prey under simulated natural conditions compared with hatchery-reared genetically wild conspecifics. However, when reared in a simulated natural environment, the difference between the two genotypes was greatly reduced.2. Here, we tested if the difference in predation rate between the two genotypes after being reared in the hatchery diminishes with time spent in a simulated natural environment. Genetically wild coho salmon reared in the hatchery were size matched to younger satiation-fed (fast-growing) and same age restricted-fed (growth rates matched to wild-type) transgenic fish. These three types of predators were released into simulated natural habitats and their effects on prey survival and growth were monitored over a 2-month period. 3. Restricted-fed, but not satiation-fed, transgenic predators consumed significantly more prey (·2AE7) relative to wild predators during the first month, with an increase to 3.8 times during the second period. Prey biomass decreased more in the presence of restricted-fed predators during the first period, but a faster growth of these prey during the second period compensated for the higher predation rate resulting in no significant difference in prey biomass among predators after 2 months. Transgenic predators grew more in length than wild type, but all three types converged in weight and condition over time. 4. Synthesis and applications. Behavioural phenotypes developed in the hatchery showed little plasticity after release. Hence, development of policy on the use of transgenic organisms must incorporate knowledge of the effect of environmental conditions, experienced by the organism prior to escape or release, on phenotype. The risk posed by culture-reared organisms may depend on the frequency of escapes, number of individuals escaping and age of escapees. Important to note is that wild-reared organisms may be biologically different from culture-reared and thus require separate evaluation. Our results will be important for science policy makers and regulators to consider when deciding whether to allow commercial application of transgenic species in aquaculture.

Growth‐enhanced coho salmon invading other salmon species populations: effects on early survival and growth

“…), whereas older GM fish appears to retain their hatchery phenotype even after being in a stream‐like environment for several months (Sundström et al . ; Sundström, Lõhmus & Devlin ), (ii) number and frequency of escapes as repeated ‘trials’ increase the chance that at least some escaped individuals will be successful (McGinnity et al . ; Kolar & Lodge ), (iii) longevity and dispersal ability of escaped individual (Sundström et al .…”

“…The only direct assessment of the impact of GM fish on other species has been through quantification of predation effects (Sundström et al . ) where GM salmon reared in the hatchery consumed more prey than non‐GM reared in the hatchery, but compensatory growth responses in prey resulted in final biomass among prey being similar across predator treatments.…”

Effects of domestication on parr maturity, growth, and vulnerability to predation in Atlantic salmon

“…In comparison, previous studies assessing growth-related survival under predation (including strains transgenic for growth hormones) were based on unknown numbers of families and parents (Biro et al 2004;Sundström et al 2004;Biro and Post 2008), similar numbers of families (four to five; Sundström et al 2009), more than five (not further specified; Sundström and Devlin 2011), or partly higher numbers of families (49 wild versus five domesticated; Vandersteen et al 2012). However, none of these studies reported to have accounted for family effects by either balancing sample sizes among families or by statistically assessing family effects on survival, although possible effects were discussed by Vandersteen et al (2012).…”

“…At this time, size differences among strains were already present. For individuals beyond the fry stage, different methods have been used to adjust body sizes between strains by using unreported methods (Biro et al 2004;Biro and Post 2008), individuals at different ages (Sundström et al 2009), matched sizes (Fleming and Einum 1997), or both the latter two in comparison ). We decided against using size-matched individuals, as in our case respective individuals from the upper or lower tail of strain size distributions are unlikely to be representative.…”

Gene–environment interactions influence feeding and anti‐predator behavior in wild and transgenic coho salmon

“…Such plasticity associated with foraging/growth/predation risk tradeoffs have likely evolved to maximize fitness in nature (Dill ), and can be sustained even when environments change (Sundström et al. ).…”