title: Electronic tagging and population structure of Atlantic bluefin tuna.
abstract: Electronic tags that archive or transmit stored data to satellites have advanced the mapping of habitats used by highly migratory fish in pelagic ecosystems. Here we report on the electronic tagging of 772 Atlantic bluefin tuna in the western Atlantic Ocean in an effort to identify population structure. Reporting electronic tags provided accurate location data that show the extensive migrations of individual fish (n = 330). Geoposition data delineate two populations, one using spawning grounds in the Gulf of Mexico and another from the Mediterranean Sea. Transatlantic movements of western-tagged bluefin tuna reveal site fidelity to known spawning areas in the Mediterranean Sea. Bluefin tuna that occupy western spawning grounds move to central and eastern Atlantic foraging grounds. Our results are consistent with two populations of bluefin tuna with distinct spawning areas that overlap on North Atlantic foraging grounds. Electronic tagging locations, when combined with US pelagic longline observer and logbook catch data, identify hot spots for spawning bluefin tuna in the northern slope waters of the Gulf of Mexico. Restrictions on the time and area where longlining occurs would reduce incidental catch mortalities on western spawning grounds.
authors.affiliation: Tuna Research and Conservation Center, Stanford University, Hopkins Marine Station, Pacific Grove, California 93950, USA. bblock@stanford.edu
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Block
authors.forename: Steven L H
authors.initials: SL
authors.lastname: Teo
authors.forename: Andreas
authors.initials: A
authors.lastname: Walli
authors.forename: Andre
authors.initials: A
authors.lastname: Boustany
authors.forename: Michael J W
authors.initials: MJ
authors.lastname: Stokesbury
authors.forename: Charles J
authors.initials: CJ
authors.lastname: Farwell
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Weng
authors.forename: Heidi
authors.initials: H
authors.lastname: Dewar
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Williams
mesh_terms: D000823:Animal Identification Systems / Q000295:instrumentation / Q000379:methods*; D025041:Animal Migration; D000818:Animals; D001267:Atlantic Ocean; D004581:Electronics; D004777:Environment; D005247:Feeding Behavior / Q000502:physiology; D008522:Mediterranean Sea; D008800:Mexico; D011157:Population Dynamics; D012098:Reproduction / Q000502:physiology; D012623:Seawater; D013696:Temperature; D013997:Time Factors; D014413:Tuna / Q000502:physiology*