Meeting Abstract
123.6 Monday, Jan. 7 Thermal Physiology of albacore tuna, , as revealed through archival tagging data SNYDER, S*; KOHIN, S; CHILDERS, J; FRANKS, P.J.S.; Scripps Institution of Oceanography, UCSD; Southwest Fisheries Science Center; Southwest Fisheries Science Center; Scripps Institution of Oceanography, UCSD smsnyder@ucsd.edu
Juvenile albacore, Thunnus alalunga, were tagged with archival tags in two regions of the Northeast Pacific: (i) off Northern Baja California, and (ii) off Washington and Oregon between 2001 and 2006 with the objective of describing seasonal movements, migration patterns, vertical distribution, and thermal physiology. Twenty tags were recovered with times at liberty ranging from 63 to 697 days. The tags’ sensors recorded depth, ambient temperature, relative light levels, and the temperature of the tuna’s peritoneal cavity every minute for the duration of the deployment. Analysis of this data revealed diel diving behavior, with repeated dives below the thermocline during the day and restriction to the mixed layer throughout the night. As temperatures below and above the thermocline are fairly homogeneous, the vertical movements of the albacore resulted in a cycling between relatively stable cold and warm thermal regimes. These cold and warm regimes were used as in situ incubation treatments. By calculating the change in internal temperature during in situ incubation treatments, the rate of heat loss due to the thermal gradient between the tuna and the surrounding water temperature was estimated. Incorporating this parameter into a heat budget model, the predicted body temperature given only the heat loss due to the temperature gradient was calculated. Change in body temperature due to metabolic heat input was then estimated as the difference between the predicted temperature and the observed temperature. Preliminary results suggest that the diving behavior and the thermal structure of the water column affect the juvenile albacore’s ability to regulate and maintain their internal temperature.
