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

What are the consequences of fishing on marine environments? Given that removing big-sized fish from the environment can have consequences beyond the population level and impact the whole biological community, we believe an eco-evolutionary perspective is key to understand the broader consequences of fishing on marine environments. In CODCHANGE, we will determine how fishing of Atlantic cod induces an evolutionary change that can impact the ecology of temperate coastal ecosystems. The eco-evolutionary knowledge and predictions that will be obtained in this project will benefit both the sustainability of cod fisheries and the conservation of biodiversity in the coastal zone. In the CODCHANGE project we will follow, in space and time, cod populations and associated coastal species in the temperate marine ecosystem of the Norwegian Skagerrak coast. The study is conducted in a network of coastal sites along the Skagerrak coast, including popular areas for recreational fishers as well as several Marine Protected Areas (MPAs) with fishing restrictions. This setting will allow us to directly observe how cod populations and associated species in the same areas respond to fishing vs. protection, giving us a unique opportunity to investigate eco-evolutionary processes in real life. By combining different tagging methods and individual-based modelling approaches, we aim to resolve how fishing affects cod at multiple scales, from genes to populations, and by including data on other fish and invertebrate species collected at the same sites, we aim to resolve the consequences of fishing vs. protection on the whole coastal biological community. We will do this in collaboration with other research groups in Norway, Spain, and the USA, who will bring their expertise in advanced modelling tools and in forecasting future environmental and management scenarios.

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.