Environmental analysis – focusing on fish

Fish are highly dependent on their surroundings and are affected by factors such as acidification, environmental toxins, invasive species, and physical changes to their habitats. Eutrophication and climate change, for example, can alter species composition. Intensive fishing often leads to the disappearance of larger, older individuals, while also weakening population regeneration.

Fish reflect both the health of the environment and the impact humans have on it.

Monitoring that reveals trends

The environmental monitoring at the Department of Aquatic Resources is based on systematic and long-term data collection, including gillnet surveys in lakes and along our coasts, electrofishing in rivers, and trawl surveys at sea. We analyse fish presence and species composition, growth, age, and sexual maturity, among other things. The results show the status of fish stocks, how much can be fished without threatening regeneration, and how the environmental conditions in our waters are changing over time.

To distinguish temporary fluctuations from real trends, high-quality data collected over extended periods is essential. Our standardised methods produce comparable data year after year, making it possible to detect changes in both stocks and the environment.

Reliable data for better decision-making

Our monitoring generates large volumes of data, both from fish surveys and laboratory analyses. These data are stored in databases that we manage and ensure are quality-assured. As the national data host, we ensure that fish data is accessible – both for today's decisions and for future research.

Through our web services, authorities, researchers, consultants, and others can easily access data to, for instance, follow up on environmental objectives, evaluate management measures, conduct environmental impact assessments, and report to international bodies such as ICES, HELCOM, and OSPAR.

Environmental analysis – the link between research and practice

Environmental analysis involves interpreting environmental data to understand why the environment is changing and what the consequences are. While environmental monitoring answers the question How is the environment doing?, environmental analysis addresses Why is it like that, and what can we do about it?. This makes environmental analysis a vital link between research and practical management.

Environmental analysis often begins with a specific question – for example, why a fish stock is declining in a lake or along the coast. Using monitoring data, and sometimes complementary studies, we analyse possible causes: is it overfishing, warmer waters, or deteriorating quality in spawning habitats?

Through expert assessments, statistical analysis and modelling, we identify patterns and relationships – and can propose solutions to improve conditions, such as habitat restoration, fishing regulations, or reducing other pressures.

A scientific basis for management

Environmental analysis is more than just numbers – it makes data meaningful and actionable. By combining long time series with in-depth analysis, we build the knowledge that politicians, authorities and managers need to make informed decisions about our aquatic environments and fish stocks – locally, regionally, nationally, and internationally.

Examples include:

• We conduct national status assessments for the most commercially important fish and shellfish stocks. These assessments are presented on www.fiskbarometern.se
  
  
• We participate in international expert groups within the International Council for the Exploration of the Sea (ICES) and HELCOM, where we contribute analyses and data to quota recommendations and environmental assessments.
  
  
• We develop indicators and methods for assessing the status of fish and ecosystems. This knowledge supports follow-up on environmental objectives and meets requirements under the EU Water Framework Directive and Marine Strategy Framework Directive.
  
  
• We provide decision support for determining whether lakes, watercourses and coastal waters have good ecological status – and what actions are needed if they do not.
  
  
• We offer scientific advice to managing authorities. Our expertise is used, for example, to evaluate measures, develop fishing regulations, and design habitat restoration plans.

Focused environmental analysis at SLU

SLU conducts environmental analysis through twelve programmes. SLU Aqua contributes in particular to the programmes Lakes and watercourses and Coastal and Sea Areas. These programmes are linked to Sweden’s environmental objectives, the global sustainable development goals, and other international environmental commitments.