Sea trout (Salmo trutta) growth patterns during early steps of invasion in the Kerguelen Islands
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Brown trout (Salmo trutta L.) was voluntarily introduced in some rivers of the Kerguelen Islands in the 1950s–1960s. Fish originating from hatcheries rapidly colonized other streams, thanks to the early occurrence of anadromous (i.e., migratory) form. Getting insight into the success of colonization requires investigating fitness-related traits such as growth and reproductive investment. In particular, increased growth and body size—traits that are broadly related to dispersal ability—are predicted on colonization front, to the possible detriment of reproductive ability. We here report such investigation on early data following the first natural reproductions in the founder populations of Kerguelen, from 1971 to 1994, assessing the main characteristic on growth at sea and reproductive investment for both sexes. Our results reveal that growth of sea trout is excellent with individuals fully benefiting from their relatively short period of growth at sea, sizes and weights ranking among the highest recorded to date. During the reproduction period, males lose on average 15–21% of their weight, whereas females lose 18–19% of their weight. Although a trade-off between growth and reproduction may arise at marginal distribution of invasive species, our study indicates that any potential advantages arising from increased growth and therefore potential dispersal ability may not be directly balanced by reduced reproductive investment, with respect to other published studies. Results overall shed light on intrinsic invasiveness of the brown trout in a post-glacial landscape with barely any interaction with human activities.
KeywordsScale reading Growth profiles Reproductive cost Feeding Salmonid Sub-Antarctic
We gratefully acknowledge the support (funding, logistics, travel) provided by the TAAF administration (Terres Australes et Antarctiques Françaises-Mission de Recherche) over all these years and their staff in Paris, La Réunion and Brest, France. This study is part of SALMEVOL-1041 program funded by the French Polar Institute (IPEV) and Institut National de la Recherche Agronomique (INRA). This study is supported by the Zone Atelier Antarctique.
Compliance with ethical standards
All procedures performed in studies involving animals were in accordance with the ethical standards of the institution or practice at which the studies were conducted.
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