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Marine Ecology Progress Series

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MEPS 368:231-239 (2008)  -  DOI:

Evidence of trans-Atlantic movement and natal homing of bluefin tuna from stable isotopes in otoliths

Jay R. Rooker1,*, David H. Secor2, Gregorio DeMetrio3, Alan J. Kaufman4, Antonio Belmonte Ríos5, Vjekoslav Ticina6

1Department of Marine Biology, Texas A&M University, 5007 Avenue U, Galveston, Texas 77551, USA
2Chesapeake Biological Laboratory, University of Maryland Center for Environmental Science, PO Box 38, Solomons, Maryland 20688, USA
3Department of Animal Health and Well-Being, University of Bari, Casamassima km 3, 70010 Valenzano (Bari), Italy
4Department of Geology, University of Maryland, College Park, Maryland 20742, USA
5Tuna Graso, S.A., Carretera de la Palma km 7, Paraje la Estrella, 30593 Cartagena (Murcia), Spain
6Institute of Oceanography and Fisheries, Set. I. Mestrovica 63, 21000 Split, Croatia

ABSTRACT: Stable carbon and oxygen isotopes in the otoliths of Atlantic bluefin tuna Thunnus thynnus were used to investigate trans-Atlantic movement and natal homing behaviors. Otolith δ13C and δ18O of yearling bluefin tuna from 6 different year classes (1999 to 2004) were characterized to validate the approach and assess inter-annual variation in these markers for individuals from eastern (Mediterranean Sea/eastern Atlantic Ocean) and western (USA Atlantic Ocean) nurseries. Otolith δ18O of yearlings from the eastern nursery were enriched relative to their western counterparts, while otolith δ13C was relatively similar between nurseries. Temporal variability in otolith δ13C and δ18O of bluefin tuna was observed; nevertheless, classification success to eastern and western nurseries was relatively high (87%) when all year classes were pooled. Otolith δ13C and δ18O of yearlings were then used as a baseline sample (‘eastern’ and ‘western’ nursery signature) to predict the origin of adolescents (20 to 70 kg) from 1 foraging area (USA Atlantic Ocean) and adults (>140 kg) from 1 spawning ground (Mediterranean Sea) based on otolith core signatures (corresponding to yearling period). Mixed-stock analysis indicated that approximately 60% of the adolescent bluefin tuna collected from foraging areas in the USA Atlantic Ocean originated from the eastern nursery, suggesting that substantial trans-Atlantic movement of adolescents from east to west occurred. In addition, natal homing was well developed, with 94% of the adult bluefin tuna collected in the Mediterranean Sea derived from the eastern nursery. Findings from this study suggest that USA fisheries depend upon migrants of Mediterranean origin and that mixing across the 45°W management boundary is substantially higher than assumed previously.

KEY WORDS: Otolith chemistry · Mixed stock fishery · Stable isotopes · Stock identification · Population structure

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Cite this article as: Rooker JR, Secor DH, DeMetrio G, Kaufman AJ, Belmonte Ríos A, Ti<ina V (2008) Evidence of trans-Atlantic movement and natal homing of bluefin tuna from stable isotopes in otoliths. Mar Ecol Prog Ser 368:231-239.

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