Integrating empirical and modelling research to assess climate change impacts on demersal fish communities

Project Information

DemFish

Grant agreement ID: 101024886

DOI

10.3030/101024886

Project closed

EC signature date 9 April 2021

Start date 1 July 2021

End date 30 June 2024

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 286 921,92

EU contribution

€ 286 921,92

Coordinated by

DANMARKS TEKNISKE UNIVERSITET
Denmark

Periodic Reporting for period 2 - DemFish (Integrating empirical and modelling research to assess climate change impacts on demersal fish communities)

Reporting period: 2023-07-01 to 2024-06-30

Summary of the context and overall objectives of the project

How much fish will there be in the future oceans, and how much of these fish can be caught by fisheries? Predicting the future of fish is an important challenge for marine science because marine fisheries are crucial for our global food and livelihood.

Scientists have created mathematical models to understand how climate change affects fish worldwide. However, these models are uncertain because we still lack knowledge about how temperature impacts different fish species and communities.

In my research, I wanted to verify the model-based predictions with new data of fish biomass from scientific surveys. Specifically, I focused on estimating the number of bottom-living fish such as cod, haddock, and flatfish. These types of fish are important for fisheries and account for 35-50% of all the fish caught globally. Yet, due to climate change, the total amount of these fish is expected to decline in the next few decades.

My project had three primary goals. First, I aimed to study the variation in bottom-living fish populations across different ocean regions and identify key factors influencing these numbers, such as temperature and fishing activity. Second, I used a mathematical model to predict the abundance of bottom-living fish and how this has changed with historical fishing. Lastly, I aimed to forecast how bottom-living fish might respond to future changes.

I found that temperature is a key driver of total fish biomass variation. This finding is consistent with our theoretical understanding of the effects of temperature on fish community biomass. It implies that demersal fish community biomass is likely to decline with ocean warming. However, trust in future projections also relies on establishing that models can accurately simulate past relationships between exploitation rates and ecosystem states. To this end, I estimated regional fishing exploitation levels from data and used these to globally simulate historical fishing patterns. The results provide capacity for the quantification of future trends in global fish biomass and potential fisheries production.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

During the first two years of my project, I conducted research at the Graduate School of Oceanography in Rhode Island, United States, under the supervision of Dr. Jeremy Collie. In this phase, I successfully achieved my first objective: identifying that temperature and fishing activity are crucial factors influencing the abundance of bottom-living fish. These findings are consistent with existing theoretical knowledge on the effects of fishing and temperature on fish biomass, providing essential empirical evidence to support model-based predictions in the context of global change. While in the United States, I also began work on both the second and third objectives of my project.

Additionally, I undertook a two-month secondment under the supervision of Dr. Katell Hamon at Wageningen Economic Research in the Netherlands. During this period, I explored the social, political, and economic factors affecting fisheries catch. This project integrated expertise from ecologists, economists, and social scientists to develop scenarios depicting potential futures for fisheries. My research indicates that current fisheries catch is significantly influenced by socio-political factors, and there are marked differences in fisheries management approaches between the European Union and North America.

In the last year of the project, I conducted research at the Technical University of Denmark. Here, I finalized both the second and third objective of my project. Among others, I used reconstructed fishing exploitation rates to simulate catch trends of diverse ecosystems on a global scale. I found that fishing has reduced the biomass of big predators (large pelagic and demersal fish) by 25% in shelf regions. This decline led to less predation on forage fish and a 50% increase in forage fish biomass, despite fishing of forage fish. These simulations allow estimating the relative effects of climate change and fishing on current and future fish communities.

I directed the exploitation of my results towards the ecosystem-modelling community as well as towards fisheries management bodies. Exploitation of the novel fish community biomass estimates was done within the EU-funded project B-USEFUL. B-USEFUL aims to create user-oriented solutions for improved monitoring and management of biodiversity. Exploitation of my mathematical modelling developments was done within the EU-funded project NECCTON. NECCTON will enable the Copernicus Marine Service to better inform ocean policymakers, managers and publics about biodiversity conservation and fisheries management, by means of new modelling products for the ocean. In addition, I joined the Fisheries and Marine Ecosystem Model Intercomparison Project (Fish-MIP). Fish-MIP is a network of more than 100 marine ecosystem modellers and researchers from around the world. Lastly, I have been actively engaged in the International Council for the Exploration of the Sea (ICES) where I have supported advisory products as well as presented my work in two working groups linked to EU fisheries management.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Theory predicts that temperature's influence on food webs in aquatic ecosystems plays a significant role in driving regional variations in total fish community biomass. However, the lack of empirical evidence supporting this pattern is problematic, as many climate projections for fish are built upon these theoretical assumptions. My project advanced the current understanding by providing empirical evidence for this long-assumed macro-ecological pattern.

Trust in future projections also relies on establishing that models can accurately simulate past relationships between fishing exploitation rates and ecosystem states. To this end, I estimated regional fishing exploitation levels from data and used these to globally simulate historical fishing patterns. In addition, I made a comprehensive assessment of the political, economic, social, technological, environmental, and legal aspects of fisheries in Alaska, northeast America, and northwest Europe. The results of this study offer valuable insights to managers by revealing the connections and trade-offs between conservation, socio-political, and economic fisheries objectives. The results will be important in the context of the European Green Deal and the EU’s aim to achieve good environmental status.

Sampling of benthic invertebrates

Illustration of developed fish community model