Evaluation of status of commercial fish stocks in European marine subareas using mean trophic levels of fish landings and spawning stock biomass

Abstract

Most of the fish stocks in the world, including European fish stocks, are threatened by overfishing and/or degraded environmental conditions. Although the Common Fisheries Policy (CFP) is the main policy instrument managing fish stocks in Europe, there is continued concern as to whether commercial fish stocks will achieve Good Environmental Status (GEnS) in 2020 in accordance with the Marine Strategy Framework Directive (MSFD). In this context, the evaluation of the status of fish stocks in the subareas of FAO fishing area 27 was carried out using mean trophic levels (MTL) in fish landings and spawning stock biomass (SSB). Comparisons were made before and after 2008 to establish whether the trend is positive or negative. The main data sources for landings and SSB were the International Council for the Exploration of the Sea (ICES) advisory reports. MTLs in landing and SSB were determined for each subarea and the subareas were categorized into four groups, according to MTLs after 2008. The first group (subareas I + II, V) had higher MTL in landings and higher MTL in SSB after 2008. Therefore, fisheries in these subareas appear sustainable. The second group was subareas VIII + IX, for which the fish stocks have higher MTL in landings but low MTL in SSB, indicating that SSB was being overfished. The third was subarea (VI), where fish stocks have lower MTL in landings than those in SSB after 2008, which may indicate that fish stocks are recovering. Fish stocks in the fourth group (subareas III, IV and VII) had low MTL in landings and the MTL in SSB was lower than that of landings before 2008. This may be due to heavy fishing. In addition, we estimated the harvest rate (HR) of the fish stocks before and after 2008. The results showed that most of the fish stocks have lower HR after 2008, indicating that the status has improved, perhaps due to improvements in the implementation of CFP. However, some fish stocks showed high HR even after 2008, so that new management options are still needed. Other factors such as eutrophication, seafloor disturbances, marine pollution, invasive species etc., influence SSB ecosystem health options and should also be incorporated in the management criteria. Most of these environmental pressures are of high priority in the MSFD, and therefore the findings of this study will be useful for both CFP and MSFD.