At-sea spatial usage of recently weaned grey seal pups in Iceland

Abstract

Although grey seals (Halichoerus grypus) are the focus of considerable research effort throughout much of their North Atlantic breeding range, little is known about grey seal movement ecology in Iceland. This is surprising given the long history of grey seal exploitation in Iceland and because grey seals are common bycatch in commercial fisheries. Here, for the first time, we deployed satellite tags on five grey seals in Iceland to quantify the at-sea spatial usage of recently weaned pups during their first year of life. Maximum foraging trip distance ranged from 20 to 160 km for individual pups, while maximum duration ranged from 4.3 to 20.8 days. Individual differences in foraging trip metrics indicated two broad strategies. Specifically, pups either remained near the deployment location or dispersed to the east of Iceland, reaching a total distance of > 300 km from the deployment location. Foraging trips were, however, typically restricted to the continental shelf, which presumably reflects a preference for benthic foraging, as is reported for grey seals at other breeding locations. Our preliminary findings highlight the importance of near-shore waters to recently weaned grey seal pups in Iceland and suggests that coastal fisheries are a prevalent threat. However, additional research is required to quantify interactions between grey seals and commercial fisheries, which in turn, would improve the efficacy of conservation and management efforts.