French Robert P, Lyle Jeremy, Tracey Sean, Currie Suzanne, Semmens Jayson M
Fisheries and Aquaculture Centre, Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania 7001, Australia.
Department of Biology, Mount Allison University, Sackville, New Brunswick, Canada E4L 1E4.
Conserv Physiol. 2015 Sep 30;3(1):cov044. doi: 10.1093/conphys/cov044. eCollection 2015.
The shortfin mako shark (Isurus oxyrinchus) is a species commonly targeted by commercial and recreational anglers in many parts of the developed world. In Australia, the species is targeted by recreational anglers only, under the assumption that most of the sharks are released and populations remain minimally impacted. If released sharks do not survive, the current management strategy will need to be revised. Shortfin mako sharks are commonly subjected to lengthy angling events; however, their endothermic physiology may provide an advantage over ectothermic fishes when recovering from exercise. This study assessed the post-release survival of recreationally caught shortfin mako sharks using Survivorship Pop-up Archival Transmitting (sPAT) tags and examined physiological indicators of capture stress from blood samples as well as any injuries that may be caused by hook selection. Survival estimates were based on 30 shortfin mako sharks captured off the south-eastern coast of Australia. Three mortalities were observed over the duration of the study, yielding an overall survival rate of 90%. All mortalities occurred in sharks angled for <30 min. Sharks experienced increasing plasma lactate with longer fight times and higher sea surface temperatures (SSTs), increased plasma glucose at higher SSTs and depressed expression of heat shock protein 70 and β-hydroxybutyrate at higher SSTs. Long fight times did not impact survival. Circle hooks significantly reduced foul hooking when compared with J hooks. Under the conditions of this study, we found that physical injury associated with hook choice is likely to have contributed to an increased likelihood of mortality, whereas the high aerobic scope associated with the species' endothermy probably enabled it to cope with long fight times and the associated physiological responses to capture.
灰鲭鲨（尖吻鲭鲨）是发达国家许多地区商业和休闲垂钓者通常的目标捕捞对象。在澳大利亚，该物种仅为休闲垂钓者的目标捕捞对象，前提是大多数鲨鱼会被放生，种群受到的影响最小。如果放生的鲨鱼无法存活，当前的管理策略就需要修订。灰鲭鲨通常会经历长时间的垂钓过程；然而，它们的恒温生理机能在从运动中恢复时可能比变温鱼类具有优势。本研究使用生存弹出式档案传输（sPAT）标签评估了休闲捕捞的灰鲭鲨放生后的存活率，并从血液样本中检查了捕获应激的生理指标以及鱼钩选择可能造成的任何损伤。生存估计基于在澳大利亚东南海岸捕获的30条灰鲭鲨。在研究期间观察到3条死亡，总体存活率为90%。所有死亡均发生在垂钓时间<30分钟的鲨鱼身上。随着搏斗时间延长和海表面温度（SST）升高，鲨鱼的血浆乳酸增加，在较高SST下血浆葡萄糖增加，在较高SST下热休克蛋白70和β-羟基丁酸的表达降低。较长的搏斗时间并未影响存活率。与J形钩相比，圆形钩显著减少了挂住鱼体其他部位的情况。在本研究的条件下，我们发现与鱼钩选择相关的身体损伤可能导致死亡率增加的可能性上升，而该物种恒温特性所具有的高有氧代谢能力可能使其能够应对较长的搏斗时间以及捕获相关的生理反应。
