An Acoustic Study on the Overwintering Black Sea Anchovy in 2020

Abstract

The Black Sea anchovy (Engraulis encrasicolus ponticus) is not only the top commercial species with around 250 thousand tonnes of annual catch but a key species of the Black Sea ecosystem facilitating the flow of energy within the food chain. The General Fisheries Commission for the Mediterranean has assessed the status of its stock for the Mediterranean since 2013. Underlining the shortcomings in the assessments, the commission has recommended diversifying and strengthening the data used and promote methods that provide biomass and abundance indices, such as hydroacoustics. This study aims to help fulfill the underlined deficiency by pursuing the implementation of the hydro-acoustic research surveys in the Turkish Black Sea EEZ. The survey was carried in November/December 2020, when the anchovies were accumulated within the Turkish EEZ, and cruise tracks were designed to cover the distribution areas of juvenile (0-year-old) and adult (Age 1 and over) anchovies displaying different distribution patterns within the Turkish EEZ in winter. The results show that the stock size is noticeably smaller than in previous years. Pelagic trawl sampling conducted alongside the acoustic data collection to estimate the size composition of anchovies indicated that the juvenile fish constitute an alarmingly large part of the overwintering stock.