The deployment of electronic data storage tags that are surgically implanted or satellite-linked provides marine researchers with new ways to examine the movements, environmental preferences, and physiology of pelagic vertebrates. We report the results obtained from tagging of Atlantic bluefin tuna with implantable archival and pop-up satellite archival tags. The electronic tagging data provide insights into the seasonal movements and environmental preferences of this species. Bluefin tuna dive to depths of >1000 meters and maintain a warm body temperature. Western-tagged bluefin tuna make trans-Atlantic migrations and they frequent spawning grounds in the Gulf of Mexico and eastern Mediterranean. These data are critical for the future management and conservation of bluefin tuna in the Atlantic.

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Pop-up satellite archival tags were attached to 35 Atlantic bluefin tuna (Thunnus thynnus) off the New England coast of the United States of America in 1998America in , 2000America in , and 2001. The tags provided information on the horizontal and vertical movements and environmental preferences of bluefin tuna. Fish showed movement patterns that can be categorized by age and season. Mature individuals were linked to the Gulf of Mexico breeding grounds based on light level longitude and sea surface temperature latitude estimates of geolocation and a radiosatellite endpoint position. A track based on geolocation indicated that a single individual moved from the tagging release location to the Gulf of Mexico and back to New England waters. Tag-generated water column profiles of depth versus temperature were consistent with fish movement along the shelf and into the Gulf of Mexico. Adolescent fish moved from the New England offshore feeding locations to winter aggregations in the coastal shelf and slope waters of North and South Carolina. Bluefin tuna showed a preference for ambient temperatures that ranged from 14 to 26°C in autumn and from 18 to 24°C in winter.

Loher, T., and A. Seitz. 2008. Characterization of active spawning season and depth for eastern Pa-cific halibut (Hippoglossus stenolepis), and evidence of probable skipped spawning. J. Northw. Atl. Fish. Sci., 41: 23–36. doi: 10.2960/J.v41.m617 The eastern Pacific halibut (Hippoglossus stenolepis) fishery is prosecuted over a nine-month season with a provision to cease harvests if stock declines to historically-observed minimum spawn-ing biomass. The industry has requested to extend fishing into winter, but little information exists regarding potential impacts on spawning aggregations or effective spawning biomass. A strictly an-nual spawning cycle is presumed, but some adults fail to undertake the offshore migration associated with continental slope spawning. We examined depth records of halibut tagged with Pop-up Archival Transmitting (PAT) tags for evidence of offshore seasonal migration (n = 72). For tags that were physically recovered (n = 16) we identified the occurrence of abrupt (~100 m) mid-winter ascents, believed to be egg release. The active spawning season, defined by occurrence of these rises, lasted from 27 December–8 March, at bottom depths of 278–594 m. Eighteen percent of tagged halibut remained onshore. Thirty-one percent of fish with detailed archival records did not exhibit spawnin