Decadal?Scale Variation in Mean Trophic Level in Beibu Gulf Based on Bottom?Trawl Survey Data

Using bottom-trawl survey data to examine fishery resources in the Beibu Gulf, South China Sea, changes stock density, dominant species composition, mean trophic level, and fishing-in-balance index were comprehensively analyzed. The results show that density of declined gulf from 1961 2017. composition trawl surveys Gulf changed greatly 1961–1962 2016–2017 showed a shift bottom pelagic high-trophic-level low-trophic-level species. Catches increased, while dominance declined. level fish 3.90 3.45 1998–1999 at rate 0.13 per decade then began increase 3.65 0.12 decade. dropped –0.96 slightly increased. indicate fisheries have been overfished. Therefore, we recommend reducing fishing pressure strengthening implementation protection measures, such as summer moratoriums, enhancement, artificial reef construction.