Precise positioning of Atlantic cod reveals size-dependent preferences for substrate and bathymetric terrain
Year: 2025
Type: article
Abstract: Atlantic cod Gadus morhua is a keystone species in the North Atlantic and Barents Sea ecosystems. Coastal Atlantic cod stocks have declined in recent decades, raising concerns about their recovery. Knowledge about cod behaviour, ecology and habitat use is vital to a management that ensures better costal cod population resilience and recovery. In this study, we aimed to quantify seascape use by Atlantic cod, using 3-dimensional acoustic telemetry to track 82 coastal cod (35-118 cm) from April through September in a 20 km 2 subarctic Norwegian fjord. We calculated continuous swimming trajectories in individual Atlantic cod with high precision (~15 m) and combined this with high-resolution bottom substrate classification and bathymetric maps with derivatives such as terrain slope and bathymetric position index. Bedrock and mixed gravel/stone substrates were among the least available habitats in the fjord, yet small cod (<55 cm) spent the most time in these habitats and avoided substrates containing mud and/or sand. Large cod (>55 cm) spent the most time in association with mud and sandy substrate. Large cod used deeper fjord parts than small cod, with only 24% overlap between the average depth distributions of the 2 size groups. Small cod were associated with steeper terrain slopes. The combination of the precise tracking method, detailed bathymetry and high-resolution habitat mapping provided new understanding of the size-dependent habitat use by Atlantic cod, and may serve as an important tool for marine research as well as coastal planning and management.
Source: Marine Ecology Progress Series
DOI: 10.3354/meps15039
Authors: Karl Øystein Gjelland, John Fredrik Strøm, Esben Moland Olsen, Henrik Baktoft, Jon Egil Skjæraasen, Torild Johansen, Nigel Brian Keeley, Eirik Emil Bygdnes, Terje van der Meeren, Pål Arne Bjørn, Thomas Bøhn
Language: English
Subfield: Global and Planetary Change
Field: Environmental Science
Domain: Physical Sciences
SDG: Life below water
Open Access status: hybrid
OpenAlex ID: W7106007914