Delayed Phenotypic Expression of Growth Hormone Transgenesis during Early Ontogeny in Atlantic Salmon (Salmo salar)? Darek T. R. Moreau 1 * ¤ , A. Kurt Gamperl 2 , Garth L. Fletcher 2 , Ian A. Fleming 1 1 Department of Ocean Sciences and Cognitive and Behavioural Ecology Programme, Memorial University of Newfoundland, St. John’s, Newfoundland & Labrador, Canada, 2 Department of Ocean Sciences, Memorial University of Newfoundland, St. John’s, Newfoundland & Labrador, Canada Abstract Should growth hormone (GH) transgenic Atlantic salmon escape, there may be the potential for ecological and genetic impacts on wild populations. This study compared the developmental rate and respiratory metabolism of GH transgenic and non-transgenic full sibling Atlantic salmon during early ontogeny; a life history period of intense selection that may provide critical insight into the fitness consequences of escaped transgenics. Transgenesis did not affect the routine oxygen consumption of eyed embryos, newly hatched larvae or first-feeding juveniles. Moreover, the timing of early life history events was similar, with transgenic fish hatching less than one day earlier, on average, than their non-transgenic siblings. As the start of exogenous feeding neared, however, transgenic fish were somewhat developmentally behind, having more unused yolk and being slightly smaller than their non-transgenic siblings. Although such differences were found between transgenic and non-transgenic siblings, family differences were more important in explaining phenotypic variation. These findings suggest that biologically significant differences in fitness-related traits between GH transgenic and non-transgenic Atlantic salmon were less than family differences during the earliest life stages. The implications of these results are discussed in light of the ecological risk assessment of genetically modified animals. Citation: Moreau DTR, Gamperl AK, Fletcher GL, Fleming IA (2014) Delayed Phenotypic Expression of Growth Hormone Transgenesis during Early Ontogeny in Atlantic Salmon (Salmo salar)? PLoS ONE 9(4): e95853. doi:10.1371/journal.pone.0095853 Editor: Zhiyuan Gong, National University of Singapore, Singapore Received October 24, 2013; Accepted April 1, 2014; Published April 24, 2014 Copyright: ß 2014 Moreau et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: Principal funding for this project was held by IAF and was part of a collaborative grant led by Dr. Eric M. Hallerman and funded by the USDA Biotechnology Risk Assessment Research Grants Program. Supplementary funding came from NSERC Discovery grants awarded to IAF, AKG and GLF. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have read the journal’s policy and have the following potentially perceived conflicts: Garth Fletcher is a minor shareholder in AquaBounty Technologies and up to approximately one year prior to the initiation of the research, was CEO of the Canadian subsidiary of the company. He is the original developer of the growth hormone transgenic Atlantic salmon, which was the result of research done at Memorial University. The lead author and all other co-authors do not have competing interests related to the research in this manuscript. This does not alter the authors’ adherence to all the PLOS ONE policies on sharing data and materials. * E-mail: dmoreau@mun.ca ¤ Current address: Department of Fisheries & Aquaculture, Government of Newfoundland & Labrador, St. John’s, Newfoundland & Labrador, Canada Introduction There is considerable interest in the application of transgenic biotechnologies to enhance animal production. Among the first animal biotechnologies to be considered commercially are growth hormone (GH) transgenic Atlantic salmon (Salmo salar L.). Similar to conventional aquaculture [1–3], there are concerns regarding the potential impacts of ecological and genetic interactions between transgenic and wild fish in nature [4–6]. As such, there is a need for empirical data with which to assess the possible environmental risks of such transgenic fish. Early ontogeny is a period of intense selection in many fish species, and thus, may provide critical information regarding the fitness of transgenic fish strains relative to wild-type individuals. For example, salmon eggs incubate in buried gravel nests that can experience lethally low levels of dissolved oxygen, resulting in high mortality [7–9]. Upon hatch, alevins (larval phase) remain underneath the gravel until their endogenous yolk reserves are near fully consumed. At this point, individuals emerge and commence exogenous feeding. First-feeding is a critical period of survival and performance for many fish species, including salmon, where the fry (early stage juveniles) must learn to attain food, compete for and/or migrate to foraging territories, and avoid predation [10–12]. Mortality during the first few weeks of life can be greater than 80% [13–15]. Thus, any transgene-induced effects on physiological and behavioural traits during early ontogeny may impact the persistence of the transgene in nature. Beyond its effects on growth [16,17], GH transgensis is known to have pleiotropic effects on other phenotypic traits in salmon, including elevated metabolic rates, increased foraging motivation and reduced anti-predator behaviour [18–23]. Many of these studies have concentrated on juveniles ca. 8 months or older, bypassing the intense selection experienced during early ontogeny. However, research with GH transgenic coho salmon, Oncorhynchus kisutch (Walbaum), has shown phenotypic effects during early life history, including reduced survival as eyed embryos during hypoxic (low oxygen) conditions [24], advanced embryo and larval development [25–27] and greater susceptibility to predation and starvation as first-feeding juveniles (fry) than non-transgenic coho [28–30]. Collectively, these studies suggest that the relative PLOS ONE | www.plosone.org 1 April 2014 | Volume 9 | Issue 4 | e95853