Local fishing closure improved European eel stock on the Swedish west coast

In 2012, a total ban on eel fishing was introduced along the Swedish West Coast, a fishing ban that was recently highlighted by an expert panel as one of the most important management measures implemented under Sweden’s Eel Management Plan. However, no scientific evaluation of its effects has been carried out until now.

Clear increase in silver eel escapement

Researchers estimate that the number of silver eels — that is, fully grown eels ready to migrate across the Atlantic to spawn in the Sargasso Sea — is now roughly twice as high as in 2011, when fishing was still allowed.

- Looking further back and comparing with the average biomass of silver eels produced during the period 1988–2011, silver eel biomass is now about four times higher, says Torbjörn Säterberg, researcher at the Department of Aquatic Resources at SLU and lead author of the study published in the scientific journal Fisheries Research.

By combining historical catch statistics from both the commercial and recreational eel fishery with data from fyke-net sampling conducted at three sites along the Swedish West Coast, the researchers sought to quantify how the eel population has developed. The estimate is based on an integrated model that combines several different data sources in a single analysis.

- The results should be interpreted with some caution, as sampling was conducted at only three sites along a long coastline. However, all data series indicate that the stock, particularly the number of larger individuals, has increased since the fishing ban came into effect in 2012, says Torbjörn Säterberg.

An important tool for Swedish eel management

The European eel has declined sharply in recent decades, and in 2007 the EU adopted a regulation aimed at rebuilding the eel population. Under this regulation, all Member States must develop an Eel Management Plan and regularly report to the European Commission on the measures implemented and the progress made.

Analytical approaches like the model developed by SLU researchers are needed to evaluate the effects of different management actions.

- We have previously developed analytical methods to monitor eel stocks along the Swedish Baltic Sea coast and in inland waters, but for the West Coast we have long lacked a tool to quantify stock size. The model developed in this study fills this gap and will constitute an important tool in Swedish eel management, says Rob Van Gemert, co-author of the study and lead scientist for the assessment of eel stocks in Swedish waters.

The article Effects of a fishery closure on the European eel stock on the Swedish west coast is published in the scientific journal Fisheries Research