Abstract
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.