Wide-Ranging Temporal Variation in Transoceanic Movement and Population Mixing of Bluefin Tuna in the North Atlantic Ocean

Frontiers in Marine Science

Michael A. Dance¹  Yohei Tsukahara²  Igaratza Fraile³  Hui Liu⁴  Tomoyuki Itoh⁵  Jay R. Rooker⁵  Noureddine Abid⁶  Enrique Rodriguez-Marin⁷  Haritz Arrizabalaga⁷  Ai Kimoto⁸ 

[1] Department of Marine Biology, Texas A&Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, LA, United States;;Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, TX, United States;M University, Galveston, TX, United States;Marine Research Division, AZTI, Pasaia, Spain;National Research Institute of Far Seas Fisheries, Japan Fisheries Research and Education Agency, Shizuoka, Japan;Regional Centre of Tangier, National Institute of Fisheries Research, Tangier, Morocco;

关键词: migration;    natal origin;    stock mixing;    Mediterranean Sea;    otolith chemistry;    stable isotopes;   

DOI  :  10.3389/fmars.2019.00398

来源: DOAJ

【 摘 要 】

Uncertainty regarding the movement and population exchange of Atlantic bluefin tuna (Thunnus thynnus) from the two primary spawning areas (Gulf of Mexico, Mediterranean Sea) is increasingly implicated as a major impediment for the conservation of this species. Here, two mixture methods were applied to natural chemical markers (δ18O and δ13C) in otoliths (ear stones) to comprehensively investigate the nature and degree of transoceanic movement and mixing of eastern and western populations in several areas of the North Atlantic Ocean that potentially represent mixing hotspots. Areas investigated occurred on both sides of the 45°W management boundary as well as waters off the coast of Africa (Morocco, Canary Islands) where both populations are known to occur. Projections of population composition (i.e., natal or nursery origin) from a multinomial logistic regression (MLR) classification method with different probability thresholds were generally in agreement with maximum likelihood estimates from the commonly used mixed-population program HISEA; however, predicted contributions for the less abundant population were occasionally higher for MLR estimates. Both MLR and HISEA clearly showed that mixing of Atlantic bluefin tuna in the Central North Atlantic Ocean was highly variable from year to year with expatriates of eastern or western origin commonly crossing into the other management area. Pronounced transoceanic movement and mixing of western migrants was also present off the coast of Africa, with the occurrence of western migrants in the Canary Islands and Morocco ranging from zero to the majority of the individuals assayed for the years examined. Results indicate highly variable rates of movement and population exchange for Atlantic bluefin tuna, highlighting the need for temporally resolved estimates of natal origin in mixing hotspots to improve population models used to evaluate the status of this threatened species.

【 授权许可】

Unknown