Evidence for Temperature Elevation in the Aerobic Swimming Musculature of the Common Thresher Shark, Alopias vulpinus
This paper reports on the in vivo temperature measurements for slow-twitch, red aerobic muscle (RM) and fast twitch, white muscle (WM) of 24 Common Thresher Sharks, Alopias vulpinus, captured off the coast of Southern California. Mean (± SE) RM temperature elevation was 2.33 ± 0.30 C warmer than the ambient sea surface temperature (SST, 19.13 ± 0.22 C) and 2.25 ± 0.35 C warmer than the coldest WM temperature measured (19.23 ± 0.30 C). The maximum RM temperature elevation was 5.4 C above SST and up to 7.6 C above the WM. Nine Common Thresher Sharks exhibited RM temperatures that exceeded 3.0 C above SST. No significant relationship was found between fish total length and RM temperature elevation. Although there was individual variability in RM temperature elevation, this study documents that the Common Thresher Shark is capable of significantly elevating its RM temperature above that of the ambient conditions.Abstract
Cross-sectional slice of Common Thresher Shark #20 taken midway along the body (under the first dorsal fin) showing the transverse trajectory in which red and white muscle temperature measurement were obtained using a thermocouple thermometer
Red muscle temperature of 24 Common Thresher Sharks. Open circles: sharks captured by longline. Filled circles sharks captured by rod and reel
Vertical temperature profile taken during the longline operation indicating measured hooking depth. Values shown are mean ± SE
Contributor Notes
(DB) Department of Zoology, Weber State University, Ogden, Utah 84408; and (CS) Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, La Jolla, California 92093-0204. E-mail (Db) dbernal@weber.edu Send reprint requests to DB.