Research press release


Scientific Reports

Marine science: Fishing drives Adriatic shark and ray declines



F Ferrettiたちは、1948~2005年に実施された5回のトロール網での調査で得られた漁獲データを統合し、標準化して、アドリア海における板鰓類の個体数の長期的傾向を評価した。その結果、板鰓類の群集は、1948年の時点ですでに枯渇しており、その後の漁獲率は、94%以上も減少し、11種が検出されなくなったことが判明した。また、Ferrettiたちは、アドリア海東部での板鰓類の個体数の増加と多様性も報告している。このことは、過去においても、最近においても、イタリアの領海よりクロアチアの領海での漁獲圧が低いことを反映している。アドリア海で観察された個体数と多様性のパターンの大部分(強い代償的増加の不存在を含む)は、過去の海域利用の歴史と漁獲圧の変化によって説明できることが、今回の結果によって明らかになっている。


Long-term changes in the shark and ray communities of the Adriatic Sea are assessed in a study published in Scientific Reports this week. The study shows that these communities have been highly depleted in recent years and that fishing has been a key driver of these changes.

The abundance of elasmobranchs, a group of cartilaginous fish that includes sharks and rays, can decline considerably with fishing, but assessing the drivers of community changes can be complicated by interactions between species and variations in vulnerability and exposure to fishing. The Adriatic Sea is a heavily exploited Mediterranean basin, but fisheries have developed unevenly between its eastern (Croatian) and western (Italian) sides.

Francesco Ferretti and colleagues combined and standardized catch data from five trawl surveys conducted between 1948 and 2005 to evaluate long-term trends in elasmobranch populations of the Adriatic Sea. Communities were already depleted in 1948, and since then catch rates have declined by more than 94%, with 11 species ceasing to be detected, the authors found. They report a greater abundance and diversity of elasmobranchs in the eastern Adriatic, reflecting the less intense historical and recent fishing pressure in Croatian compared to Italian waters. The exploitation history and changes in fishing pressures could explain most of the observed patterns of abundance and diversity, including the absence of strong compensatory increases, the results show.

The study suggests that careful planning and international management of developing fisheries in the Adriatic and the creation of ecological corridors and large-scale protected areas could help to promote recovery among shark and ray communities throughout this sea.

doi: 10.1038/srep01057


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