title: Discovery of a spawning ground reveals diverse migration strategies in Atlantic bluefin tuna (Thunnus thynnus).
abstract: Atlantic bluefin tuna are a symbol of both the conflict between preservationist and utilitarian views of top ocean predators, and the struggle to reach international consensus on the management of migratory species. Currently, Atlantic bluefin tuna are managed as an early-maturing eastern stock, which spawns in the Mediterranean Sea, and a late-maturing western stock, which spawns in the Gulf of Mexico. However, electronic tagging studies show that many bluefin tuna, assumed to be of a mature size, do not visit either spawning ground during the spawning season. Whether these fish are spawning in an alternate location, skip-spawning, or not spawning until an older age affects how vulnerable this species is to anthropogenic stressors including exploitation. We use larval collections to demonstrate a bluefin tuna spawning ground in the Slope Sea, between the Gulf Stream and northeast United States continental shelf. We contend that western Atlantic bluefin tuna have a differential spawning migration, with larger individuals spawning in the Gulf of Mexico, and smaller individuals spawning in the Slope Sea. The current life history model, which assumes only Gulf of Mexico spawning, overestimates age at maturity for the western stock. Furthermore, individual tuna occupy both the Slope Sea and Mediterranean Sea in separate years, contrary to the prevailing view that individuals exhibit complete spawning-site fidelity. Overall, this complexity of spawning migrations questions whether there is complete independence in the dynamics of eastern and western Atlantic bluefin tuna and leads to lower estimates of the vulnerability of this species to exploitation and other anthropogenic stressors.
authors.affiliation: Northeast Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Narragansett, RI 02882; David.Richardson@noaa.gov.
authors.forename: David E
authors.initials: DE
authors.lastname: Richardson
authors.affiliation: Integrated Statistics, Contractor for Northeast Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Narragansett, RI 02882;
authors.forename: Katrin E
authors.initials: KE
authors.lastname: Marancik
authors.affiliation: Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Juneau, AK 99801;
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Guyon
authors.affiliation: Large Pelagics Research Center, School for the Environment, University of Massachusetts Boston, Gloucester, MA 01931;
authors.forename: Molly E
authors.initials: ME
authors.lastname: Lutcavage
authors.affiliation: School of Marine Science and Technology, University of Massachusetts Dartmouth, Fairhaven, MA 02719; Greater Atlantic Regional Fisheries Office, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Gloucester, MA 01930.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Galuardi
authors.affiliation: Large Pelagics Research Center, School for the Environment, University of Massachusetts Boston, Gloucester, MA 01931;
authors.forename: Chi Hin
authors.initials: CH
authors.lastname: Lam
authors.affiliation: Northeast Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Narragansett, RI 02882;
authors.forename: Harvey J
authors.initials: HJ
authors.lastname: Walsh
authors.affiliation: Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Juneau, AK 99801;
authors.forename: Sharon
authors.initials: S
authors.lastname: Wildes
authors.affiliation: Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Juneau, AK 99801;
authors.forename: Douglas A
authors.initials: DA
authors.lastname: Yates
authors.affiliation: Northeast Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Narragansett, RI 02882;
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: Hare
mesh_terms: D025041:Animal Migration; D000818:Animals; D001267:Atlantic Ocean; D012098:Reproduction; D014413:Tuna / Q000502:physiology*
keywords: Scombridae; ichthyoplankton; large pelagic fish; pop-up satellite archival tag; population structure