Bluefin Tuna: Ours or Theirs? (link to brochure)
For Atlantic bluefin tuna fisheries, mixed stock fisheries are well documented for the US shelf waters where two populations - originating either in the Gulf of Mexico or Mediterranean - contribute equivalent numbers (Rooker et al.
2009; Secor et al. 2011). The assessment model for the western stock
(virtual population analysis) is heavily influenced by US catch indices, which
in recent years have shown a strong 2003 year-class (ICCAT 2011). This
is important because recruitment has been persistently low during the past 30
But to determine whether the western stock has returned to historical levels of high recruitment, the 2003
year-class must be identified according to its population of
origin. Preliminary evidence, based on otolith stable isotope analysis indicates
that this year-class is not solely due to juveniles produced from the Gulf of
Mexico population (Secor et al. 2011).
The degree of stock mixing by bluefin tuna in eastern Atlantic waters (Europe and other Mediterranean nations) remains poorly known, but because the Mediterranean population is c. ten-fold more productive and supports higher fishing rates, catches there will disproportionately affect the Gulf of Mexico population, which has been in a long-term but unsuccessful rebuilding plan (Taylor et al. 2011). This is a common attribute of mixed stock fisheries, where less productive stocks receives higher proportional removals; in these instances, management controls should guard against overharvest of the more susceptible stock.
Up to 60% of US recreationally-caught bluefin tuna started life in the Mediterranean Sea.
Juvenile bluefin tuna
Secor, D.H., B. Gahagan, and J.R. Rooker. (2011). Atlantic bluefin tuna population assignment based on otolith stable isotopes: the 2003 year-class within the U.S. North Carolina recreational fishery. International Commission for the Conservation of Atlantic Tunas SCRS/2011/169. Madrid.
Restrepo, V.R., G.A. Diaz, J.F. Walter, J. Neilson, S.E. Campana, D. Secor, and R.L. Wingate. 2010. An updated estimate of the growth curve of Western bluefin tuna. Aquatic Living Resources 23: 235-342.
Secor, D.H. 2010. Is otolith science transformative? New views on fish migration. Environ. Biol. Fishes 89: 209-220.
Schloesser, R.W., J.D. Neilson, D.H. Secor, and J.R. Rooker. 2010. Natal origin of Atlantic bluefin tuna (Thunnus thynnus) from the Gulf of St. Lawrence based on otolith δ13C and δ18O. Canadian Journal of Fisheries and Aquatic Sciences 67: 563-569.
Schloesser, R.W., J.R. Rooker, P. Louchuoarn, J.D. Neilson, and D.H. Secor. 2009. Inter-decadal variation in ambient oceanic δ13C and δ18O recorded in fish otoliths. Limnology and Oceanography 54(5): 1665-1668.
Dickhut, R.M., A.D. Deshpande, A. Cincinelli, M.A. Cochran, S. Corsolini, R.W. Brill, D.H. Secor, and J.E. Graves. 2009. North Atlantic bluefin tuna population dynamics delineated by organochlorine tracers. Environmental Science and Technology 43:8522-8527.
Rooker, J.R., D.H. Secor, G.D. DeMetrio, R. Schloesser, B.A. Block, and J.D. Neilson. 2008. Natal homing and connectivity in Atlantic bluefin tuna populations. Science 322: 742-744.
Rooker, J.R., D. H. Secor, G. DeMetrio, A.J. Kaufman, A.B. Ríos, V. Tičina, E. Rodríquez-Marín. 2008. Evidence of trans-Atlantic movement and natal homing in bluefin tuna from stable isotopes in otoliths. Marine Ecology Progress Series. 368:231-239.
Secor, D.H., R.L. Wingate, J.D. Neilson, J.R. Rooker, and S.E. Campana. 2008. Growth of Atlantic bluefin tuna: Direct age estimates. Collective Volume of Scientific Papers, ICCAT SCRS/08/084. 14 pp.
Arslan, Z. and D.H. Secor. 2008. High resolution micromill sampling for analysis of fish otoliths by ICP-MS: effects of sampling and specimen preparation on trace element fingerprints. Marine Environmental Research 66: 364-371.
Rooker, JR, JR Alvarado-Bremer, BA Block, JL Cort, H Dewar, G De Metrio, RT Kraus, ED Prince, E Rodriquez-Marin, DH Secor. 2007. Life history and stock structure of Atlantic bluefin tuna (Thunnus thynnus). Reviews in Fisheries Science 15:265-310.
Secor, D.H. 2006. Do some Atlantic bluefin tuna skip spawning? Collective Volume of Scientific Papers, ICCAT SCRS/06/088. 16 pp.
Rooker, J.R., D.H. Secor, V.S. Zdanowicz, G.De Metrio, and L.O. Relini. 2003. Identification of Atlantic bluefin tuna stocks from putative nurseries using otolith chemistry. Fisheries Oceanography 12: 75-84.
Secor, D.H. 2002. Is Atlantic Bluefin tuna a metapopulation? Collective Volume of Scientific Papers, ICCAT SCRS/01/056.54(2):390-399.
Secor,D.H, S.E. Campana, V.S. Zdanowicz, J.W.H. Lam, L. Wang, and J.R. Rooker. 2002. Inter‑laboratory comparison of Atlantic and Mediterranean Bluefin tuna otolith microconstituents. ICES J. Mar. Sci. 59: 1294-1304.