Data Collection

How We Monitor Sweden's Fish Stocks

Rather than attempting the impossible—counting every fish in the sea—we use mathematical models, which are filled with data from our various surveys, to estimate fish stocks.

Fisheries-Dependent and Fisheries-Independent Data

In our models, we use both fisheries-dependent and fisheries-independent data. Fisheries-dependent data includes information from commercial fisheries logbooks, recreational fisheries, and sampling conducted aboard fishing vessels and in ports. Fisheries-independent data, on the other hand, is collected directly by us through systematic surveys. This approach allows us to compare data across years, time periods, and between different areas and species.

Data Collection Along the Coast and in Freshwater

We are responsible for collecting data, conducting stock analyses, and providing biological assessments to management authorities for nationally managed fish stocks in Sweden. This includes coastal and inland species such as perch, pike, zander, and whitefish. Our data collection involves coordinated sampling along the entire Swedish coastline, in our five largest lakes (Vänern, Vättern, Mälaren, Hjälmaren, and Storsjön), in smaller lakes, and through data from commercial fisheries. This information helps us estimate fish populations and offer advice on sustainable fishing limits. All the data we collect is stored in SLU's databases.

Data Collection in the Baltic Sea and the North Sea

Many fish species migrate across vast areas and are not confined to national fishing zones, making international cooperation essential. Each year, we conduct six internationally coordinated trawl surveys in the Baltic Sea, the Bothnian Sea, the Kattegat, and the Skagerrak. These surveys aim to collect fisheries-independent estimates of fish populations and larvae in various regions. The surveys are organized in collaboration with the International Council for the Exploration of the Sea (ICES).

Data collection within the EU's Common Fisheries Policy

A key part of our mission is to collect data that supports the EU's Common Fisheries Policy.

In Sweden, the Swedish Agency for Marine and Water Management (HaV) is responsible for implementing and coordinating the national data collection program (DCF - Data Collection Framework) across commercial fishing, recreational fishing, and aquaculture. This program, part of the EU's Common Fisheries Policy, aims to gather and analyze data on fishing activities, fish stocks, and ecosystems.

On behalf of HaV, we carry out the majority of the program. This includes collecting samples from vessels and landed catches, gathering data on key commercial inland fish stocks in Sweden, and sampling in recreational fisheries. We also conduct trawling and acoustic surveys using research vessels. Additionally, we analyze data on species abundance, age, size, and sex to assess the development of fish stocks.

Common Species We Study

The national data collection program (DCF) includes sampling of various species. While the specific species studied may vary, in Sweden, it typically includes:

• Cod
• Herring
• Salmon
• Plaice
• European flounder
• Trout
• Eel

Our mission also involves collecting data and evaluating the amount of fish caught in recreational fishing. In Sweden, this means estimating the annual catch of cod and salmon (by weight) in recreational fisheries.

How Our Data is Used in the National Data Collection Program (DCF)

We gather data on fish and fisheries, which is then used by working groups within the International Council for the Exploration of the Sea (ICES) to estimate fish stock levels. We actively participate in these working groups as well. These stock estimates form the foundation for providing biological advice on fish stocks and guiding fisheries management within the EU.

Go directly to

• Recreational fishing data collection
• Eel data collection
• Salmon data collection
• Internationally coordinated trawl surveys in the Baltic Sea and the North Sea
• On-board and port sampling
• Coastal trawl sampling
• Coastal fish stock monitoring