Intrinsic tracers reveal recent foraging ecology of giant Pacific bluefin tuna at their primary spawning grounds

Marine Ecology Progress Series

Daniel J. Madigan¹  Takashi Kitagawa¹  Jocelyn Tallmon¹  Nazmul Ahmed¹  Brian N. Popp¹  Chi-lu Sun¹  Wei-Chuan Chiang¹  C. Anela Choy¹  Natalie J. Wallsgrove¹  Nicholas S. Fisher¹ 

关键词: Thunnus orientalis;    Stable isotopes;    AA-CSIA;    Diet;    Trophic;   

DOI  :  10.3354/meps11782

学科分类：海洋学与技术

来源: Inter-Research

【 摘 要 】

ABSTRACT: Pacific bluefin tuna Thunnus orientalis (PBFT) play important economic and ecological roles in the western Pacific Ocean. We currently lack basic information on PBFT foraging that would facilitate ecologically informed recovery strategies for this species. We used stable isotope analysis to investigate recent (previous ~1.5 yr based on isotopic turnover rate) trophic ecology of 261 giant (>180 cm), sexually mature PBFT entering their major spawning grounds off Taiwan. We performed amino acid-compound specific isotope analysis (AA-CSIA) on a subset of PBFT and select prey to assess the trophic position of PBFT in the western Pacific and to validate putative recent trans-Pacific migration from the eastern Pacific Ocean. Bayesian isotopic mixing model results suggested recent PBFT foraging off eastern Japan and in the Kuroshio-Oyashio transition region, with minimal inputs from the Sea of Japan and Taiwan waters. PBFT did not appear to feed primarily on zooplanktivorous forage fish (e.g. sardine, anchovy) but on higher trophic-level prey including mackerels, squids, and pomfrets. AA-CSIA confirmed a high trophic position (>5) of PBFT in this region and identified putative recent trans-Pacific migration of 2 individuals. This study identifies the prey base that sustains giant PBFT before migrating to spawning grounds off Taiwan and sets the stage for future studies comparing the movements and ecology of PBFT in the western Pacific Ocean.

【 授权许可】

Unknown