నైరూప్య

Physiological and behavioral effects of angling on California sheephead (Semicossychus pulcher): Response, recovery, and captivity stress of an important gamefish in Southern California

Caitlin R. McGarigal

California sheephead, Semicossyphus pulcher, have experienced significant population declines in recent decades but have remained an important nearshore gamefish in southern California by hook and line anglers. Regulations in the recreational sector currently include a minimum size and bag limit; however, the resulting widespread catch and release practices have unknown physiological and behavioral impacts on S. pulcher individuals and population. The objective of this study was to evaluate the sublethal responses of S. pulcher to catch and release fishing, determine the potential impacts of current management strategies, and recommend best practices for anglers to minimize fish stress. Physiological responses were measured for known stress indicators (cortisol, glucose, lactate) in blood samples collected after varying angling and confinement treatments, while fish behavior was evaluated by active tracking of S. pulcher with acoustic transmitters. We found that baseline biomarker levels were comparable to other teleosts, although blood collected using a novel underwater sampling method exhibited lower levels than reported for other marine fish. It was also determined that biomarkers were significantly elevated the longer fish fought on the line up to 20 min (p<0.001) while concentrations continued to peak levels in fish held captive for up to 2 h post-capture. However, caught fish released back into their natural environment and subsequently resampled showed full recovery of cortisol to baseline levels even in fish resampled as early as 18 h post-hooking (p>0.05). By contrast, fish held in captivity after catching maintained elevated glucose and cortisol levels for 14 and 30 d, respectively (p>0.01). Behavioral evaluations indicated that caught and released males used significantly more area and had higher rates of movement, as compared with females in the first 24 h post-release; however, there were no discernable differences between angled and control fish. The results of this study indicate that catch and release angling results in physiological stress for S. pulcher, but this can be reduced by minimizing fight times and handling before returning the fish back into their home environment. Rapid recovery (in <18 h) and the lack of behavioral impacts supports catch and release as a viable management strategy for this species.