Beneath the surface: profiling blubber depth in pinnipeds with infrared imaging.
Infrared thermography (IRT) was assessed as a non-invasive tool to evaluate body condition in juvenile female harbor seals (Phoca vitulina), (n=6) and adult female Steller sea lions (Eumetopias jubatus), (n=2). Surface temperature determined by IRT and blubber depth assessed with portable imaging ultrasound were monitored concurrently at eight body sites over the course of a year in long-term captive individuals under controlled conditions. Site-specific differences in surface temperature were noted between winter and summer in both species. Overall, surface temperature was slightly higher and more variable in harbor seals (9.8±0.6°C) than Steller sea lions (9.1±0.5°C). Limited site-specific relationships were found between surface temperature and blubber thickness, however, insulation level alone explained a very small portion of the variance. Therefore, while validated IRT data collection can potentially provide valuable information on the health, condition and metabolic state of an animal, it cannot provide a generalized proxy for blubber depth.
Alaska SeaLife Center, PO Box 1329, 301 Railway Avenue, Seward, AK 99664, United States; School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, AK 99775, United States. Electronic address: joannm@alaskasealife.org.
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Nienaber
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Polasek
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Horning
D000273:Adipose Tissue / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology*; D000818:Animals; D001831:Body Temperature; D010872:Caniformia / Q000033:anatomy & histology / Q000502:physiology*; D005260:Female; D007259:Infrared Rays; D009928:Organ Specificity; D012621:Seasons; D013817:Thermography; D014463:Ultrasonography