Effects of a fishery closure on the European eel stock on the Swedish west coast

Fishing bans are implemented as management measures aimed at rebuilding depleted stocks, albeit with varying levels of success. In 2012, the commercial fishery for the European eel stock on the Swedish west coast was closed to increase the spawning migration from this local stock. However, despite being regarded as one of the most important management measures implemented in Swedish eel management, an assessment of the effects of this fishing closure on the eel stock has not previously been conducted. Here, in an integrated analysis, we use historical catch data in conjunction with standardized fisheries independent fyke-net data from three sites along the Swedish west coast to build a novel stock assessment model to quantify the effects of the fishery closure. The model is length-based, and escapement rates-that is, the rate at which eels escape from the system to migrate to and spawn in the Sargasso Sea-are estimated as an integral part of the analysis. Our results suggest that total escapement has increased fourfold compared to historical levels (compared to 1988-2011) and that the stock has reached its potential maximum escapement under current low recruitment conditions. Hence, the fishing closure seems to have had its intended effect of rebuilding a depleted stock, though it should be acknowledged that post fishing closure estimates of eel escapement are based on survey data from only three local sites. Nevertheless, our study constitutes a rare example of where the effects of management actions targeting European eel have been quantified.