Many factors influence the physiological stress response to fisheries capture in elasmobranchs.
However, the influence of sea surface temperatures (SST) and behaviour are
unknown and crucial considering global fishing pressures. We investigated the effect of
SST and behaviour on the physiological stress response to capture of the gummy shark,
Mustelus antarcticus, and compared our results to a laboratory study using similar conditions
to test whether stress responses of in situ capture are consistent with those from laboratory
simulations. Capture time for 23 M. antarcticus ranged 32–241 min as measured by
hook timers or time depth recorders (TDR) in SSTs ranging 12–20°C. TDR data from 13 M.
antarcticus were analysed to quantify capture behaviour as the percentage of time spent
moving during capture. Several physiological variables measured from blood samples
obtained immediately upon the animals’ landing indicated that although warmer SSTs
increased metabolic rate, the stress response to capture was not exacerbated by capture
duration. During capture movement occurred for an average of 10% of the time and since
M. antarcticus can respire whilst stationary, restricted movement probably mitigated potential
influences of increased SSTs and capture duration on the stress response. Previous
laboratory findings were also shown to be indicative of in situ conditions and we thus advise
that studies control for water temperature given the influence it has on variables (e.g. lactate)
used to measure capture stress in elasmobranchs. We highlight the importance of seasonal
water temperatures and capture behaviour when assessing the resilience to fisheries
capture and the implementation of appropriate fisheries management strategies.