Marine habitat use and feeding ecology of introduced anadromous brown trout at the colonization front of the sub-Antarctic Kerguelen archipelago

Jan Grimsrud Davidsen (1) , Xavier Bordeleau (2, 3) , Sindre Håvarstein Eldøy (1) , Frederick Whoriskey (4) , Michael Power (5) , Glenn T Crossin (2) , Colin Buhariwalla (6) , Philippe Gaudin (7)

1 NTNU University Museum [Trondheim]
2 Dalhousie University - Department of Biology
3 Department of Fisheries and Oceans Canada
4 Ocean Tracking network
5 University of Waterloo [Waterloo]
6 Nova Scotia Department of Fisheries and Aquaculture
7 ECOBIOP - Ecologie Comportementale et Biologie des Populations de Poissons

Abstract In 1954, brown trout were introduced to the Kerguelen archipelago (49°S, 70°E), a pristine, sub-Antarctic environment previously devoid of native freshwater fishes. Trout began spreading rapidly via coastal waters to colonize adjacent watersheds, however, recent and unexpectedly the spread has slowed. To better understand the ecology of the brown trout here, and why their expansion has slowed, we documented the marine habitat use, foraging ecology, and environmental conditions experienced over one year by 50 acoustically tagged individuals at the colonization front. Trout mainly utilized the marine habitat proximate to their tagging site, ranging no further than 7 km and not entering any uncolonized watersheds. Nutritional indicators showed that trout were in good condition at the time of tagging. Stomach contents and isotope signatures in muscle of additional trout revealed a diet of amphipods (68%), fish (23%), isopods (6%), and zooplankton (6%). The small migration distances observed, presence of suitable habitat, and rich local foraging opportunities suggest that trout can achieve their resource needs close to their home rivers. This may explain why the expansion of brown trout at Kerguelen has slowed.

Mots clés: kerguelen; antarctic; marine habitat; feeding ecology

Domaines: Biodiversité et Ecologie; Ecologie, Environnement

Jan Grimsrud Davidsen, Xavier Bordeleau, Sindre Håvarstein Eldøy, Frederick Whoriskey, Michael Power, et al.. Marine habitat use and feeding ecology of introduced anadromous brown trout at the colonization front of the sub-Antarctic Kerguelen archipelago. Scientific Reports, 2021, 11 (1), ⟨10.1038/s41598-021-91405-x⟩. ⟨hal-03451892⟩