Atlantic Bluefin Tuna, A Fish Too Cool For Its Own Good? Walt Golet University of Maine, GMRI Presentation Outline Life History Morphological Characteristics Specific adaptations (physiology) Fisheries Past and Present Gear Types Past and Present Markets Management National and International Stocks Quotas Science Outstanding Questions Research tools to answer these questions What does the future hold? Picture1a Life History Characteristics IGFA Record >10ft >1500 Pounds Specialized circulatory system Warm-bodied due to rete mirabile results in warm gut, eyes, muscles Gill surface area and blood water barrier ten times different from other fish Increased levels of hemoglobin and myoglobin, efficient at removing lactic acid Negatively buoyant Skull fused only ram feed and ventilate High aspect ratio tail, high thrust low drag Have their own distinct form of swimming Eastern Atlantic Bluefin Fishery Ancient in origin, pre-Aristotle, 7th millennia BC! Between the 17th and early 20th century traps dominated the Med for bluefin fishing Modern fishing technologies (purse seine) developed in the 1920’s by the Norwegians Western Atlantic Fishery Started in the early 20th century Four gear types- -Longline- only as by-catch no direct fishery -Purse Seine-five permits currently only one fishes -Harpoon-~30 boats -Rod and Reel (commercial and recreational) largest gear type ~ 35,000 permits IMG_1116 IMG_1127 Markets….What happens to these fish? Pre 1970’s canneries only wanted small fish Post mid-1970’s shift to large high fat content fish U.S. has the largest and only self-imposed minimum size (73 inches) Commercial fish are sold domestically and internationally (typically to Japan) Recreational for personal consumption only 2011 set record one tuna sold for $396,000 $531/lb!! Typical prices are $6.00 to $12.00/lb History of Bluefin Tuna Management in the Atlantic Initially none, catches largely unregulated 1966 initial stages for organizing what would formally be known as the International Commission for the Conservation of Atlantic Tunas (ICCAT) 48 Countries which all try to agree on who gets what for quota, makes it fun Despite this early date, quotas not implemented by ICCAT until 1982 for western Atlantic Quotas allocated based on historical catches…… Current Management Boundary…does this make sense and why? Stock size ten times larger in Eastern Atlantic Juveniles present on both sides Mixing across the line thought to be minimal (more on this later) Separate spawning areas, possible fidelity to these areas Vastly different maturity schedules………4 yrs in the eastern Atlantic versus 8-10 yrs in the western Atlantic Western Atlantic The western Atlantic typically gets about 2,000 metric tons annually, changes between assessments, the east typically was allocated 32,000mt (likely 64,000)! U.S. historical catch allowed us to retain 57% of entire western quota Canada and Japan each get about 24% of the remainder Division of Quota in U.S. 2011 General Category ~ 404mt Harpoon ~33.5mt Purse Seine~159.7mt Long line~69.5mt Angling~169mt Trap~.9mt Reserve ~21.5mt ~ 5,000-7,000 fish harvested in total Outstanding Questions…… How Many Fish Are There? Difficult question for all species of fish Options: Use catch data to estimate previous population size (current method)…..what if distributions shift? Aerial surveys Sonar work Inter-annual Shifts in Distribution 1994 1995 1996 1994 1995 1996 What Drives These Shifts? Prey Likely the Most Important Driver Age and Growth…….How Old Are They and How Fast Do They Grow? Small Differences Have a Big Impact 58-2005B 25 Yrs Old Calanus C5-C6 Freshwater, Stratification, Flow herr300 267bft Small copepods Herring Abundance Fall Bloom cal ? Herring Condition ? Bluefin Condition Spring Bloom Ecosystem Work Reproduction, Size at Sexual Maturity Examination of the gonads, sample different size fish at different locations (spawning grounds)………difficult on a large scale given the life history of this species Hormone analysis to identify when fish enters puberty (capable of spawning) and the percent of each age category that have the ability Larval surveys, expensive, impractical over large areas of ocean Ideal world use a spawning tag, not available yet Two Different Types of Tags Fishery Dependent Conventional Streamer Tags Daily Diary Tags Implanted Archival Tags Fishery Independent Satellite Tags (GPS) PSAT-Pop-up Satellite Archival Tags Tag records: Water Temp Depth Location VIDEO 2 C:\Ben\UNH\PROJECTS\PSAT\GOME2002_2003\JBFT_2007-2009.png X-tagged juvenile bluefin tuna (n = 26) 2007 - 2010 PSAT 2005-2006 UKF_BFITS_ReturnTrips There and Back Again…. Tuna Know Where They Are Schools Moving East? Are Bluefin Doomed to Extinction? Highly Unlikely Appears to be several upcoming year classes based on size composition of the catch U.S. caught almost all of their quota last year and are doing well this year Previous success stories: Broadbill swordfish, once thought to be extremely overfished are now considered fully rebuilt and the average size has jumped from 90 to almost 300 pounds! Thank You…….Questions?