The importance of tagging for eco-evolutionary studies

Did you know that more than 12,000 Atlantic cod have been tagged with T tags (like the one in the image) along the southern coast of Norway?

Tagging helps us identify individual fish and monitor them over time, giving us information on both movements and mortality, as tagged cod can also be recovered dead in commercial and recreational fisheries. Therefore, mark-recapture methods provide essential individual information that is key to understanding biological processes at the population level. In the CodChange project, we will use extensive collection of mark-recapture and telemetry data across multiple sites and years to answer important questions about the phenotypic selection and population dynamics of Atlantic cod in Skagerrak. Previous studies analyzing some of this data have revealed that around 90% of the annual mortality of sexually mature cod is related to fishing, with annual survival being approximately 30% (read the article here: https://doi.org/10.1139/cjfas-2015-0313). Current fisheries are therefore not sustainable and sound knowledge about their ecological and evolutionary implications is urgently needed to improve both their management and biodiversity conservation in Skagerrak.