Conservation translocation of Atlantic wolffish (Anarhichas lupus) to a depleted Arctic fjord ecosystem

Large predators can have important functional roles in coastal ecosystems. In cases where such species are locally depleted or extirpated, a proactive restoration strategy may include conservation translocation. This study reports on such translocations of Atlantic wolffish (Anarhichas lupus) to fjord habitats in northern Norway where the species is currently severely depleted. A total of 20 pioneer individuals measuring 42 – 80 cm in length were captured in outer coastal habitats and subsequently tagged, released, and tracked within a fjord using acoustic telemetry. A first group of seven individuals were monitored for 14 months during 2017 and 2018 while a second group of 13 individuals were monitored for four months during 2019. Up to 40% of translocated wolffish remained inside their new fjord environment until the study was terminated, while the remaining 60% likely dispersed. Weekly home range size decreased substantially with time for larger fish while this trend was weaker for smaller fish. Our study implies that there is reason for cautions optimism regarding the implementation of conservation translocation of wolffish in coastal ecosystems.

Methods
Atlantic wolffish were captured in the wild, tagged with acoustic transmitters, and translocated to to the inner part of a fjord where their movements and fate wre monitored within a fixed array of acoustic telemetry receivers. Detection data were downloaded at the end of the study, and thereafter processed and analysed using several scripts witin the R software.