Fishing-induced eco-evolutionary changes in coastal environments: Atlantic cod as a case study

The project started officially the 16th of October 2023, when a collaboration agreement was signed among all project partners. A first project meeting was held online the 22nd of February 2024, to decide what would be the focal tasks for the upcoming year. Partners from Norway and Spain directly participated to the meeting, while the American partners sent their feedback after the meeting. A second project meeting will be held at the University of Oslo the days 4-5th of November 2024. Since the start of the project, we have had access to existing long-term individual data of coastal cod in Skagerrak (telemetry and capture-recapture data) and data on other species from the same coastal communities (e.g., European lobster and several species of wrasse). A manuscript investigating sex ratio, length, and ecotype disparities in juvenile cod (and arising from the above dataset) has been submitted and is now under review in Fish Biology. A demographic analysis combining genetic identity and capture-recapture data of coastal cod from Tvedestrand fjord (Skagerrak) started in February, generating annual survival estimates for the different genetic units or cod ecotypes coexisting in the area. The obtained estimates will contribute to a broader understanding of the population dynamics of coastal cod ecotypes under different harvest scenarios (WP2 of the project) and a manuscript describing the analysis and its results is under preparation. In parallel, a spatial capture-recapture analysis of data on European lobster from 3 MPAs and fished areas in Skagerrak has now been completed, generating home range estimates of male and female lobster at multiple locations over 2 decades. Despite not focusing on coastal cod, that research is aligned with the objectives of WP1(to investigate selection of traits with and without dishing) and a manuscript with the results of that analysis is under preparation. The 25th of March 2024, a 2-year postdoctoral position at IMR linked to this project was announced in the jobbnorge portal, with application deadline 30th of April 2024. The postdoc will mainly work on the research objectives of WP1, using telemetry data of coastal cod from Tvedestrand fjord. For that postdoctoral position, we received 17 applications in jobbnorge and we interviewed 5 highly-qualified applicants. The first ranked applicant (Dr. Martina Martorell Barcelo) accepted the job offer and will start her position at IMR the 1st of October 2024. Since October 2023, the scientific scope and objectives of the project have been presented at two seminars organized at the IMR units in Tromsø (17th of November 2023) and Flødevigen (1st of December 2023), and a project’s website has been launched in November 2023. The website is also connected to a Facebook page where we post news and information about the project. In addition, some results of our research on coastal cod ecotypes in Skagerrak were presented at the FSBI Symposium held the 15th - 19th July 2024 in Bilbao (Spain).

Human-induced ecosystem change can occur in only a few years and can be detected at different levels of biological complexity. Fishing in particular can cause rapid phenotypic change by affecting size-dependent mortality at the individual level, altering population structure, species interactions and eventually community dynamics. Because of these cascading effects, an eco-evolutionary perspective is needed to understand the ecosystem effects of fisheries. However, to achieve such understanding, we need to compare human-impacted areas with others that remain undisturbed. In this project we will examine the ecosystem effects of the Atlantic cod fishery in Skagerrak (Norway), with the aim to generate robust evidence-based knowledge for a sustainable management of coastal ecosystems. Several Marine Protected Areas (MPAs), offering full to partial protection from fisheries to Atlantic cod, were established in Skagerrak between 2006-2012 and will be used here as reference sites to investigate the eco-evolutionary effects of cod fishing. Scientific monitoring of these MPAs and adjacent harvested areas has generated a unique collection of data on both cod and associated species that we will analyze in this project to fill knowledge gaps on different processes at the individual, population and community levels, using novel and flexible modelling tools. This approach will allow us to obtain urgently needed demographic quantities (i.e. natural mortality, home range size, population growth rates under different harvest scenarios) and knowledge of predictor-response relationships (i.e. body size effects on cod mortality, cod population effects on community composition) for multiple cod populations and associated biological communities within MPAs and harvested areas. These expected results will enhance both marine biodiversity conservation and the evidence-based management of MPAs and coastal cod fisheries in Norway.