Sharks, Rays, and Chimaeras: reflex impairment and delayed mortality

Recent field research on sharks, rays, and chimaeras quantifying post-capture survival (PCS) has shown that:

 "As in any risk assessment, the methodology presented in this study is a first step to indentifying which species are more at risk. It provides an alternative and demonstrates that we are able to gain comparable knowledge on PCS for a large number of species from observations conducted on board commercial fishing vessels. All species showed little variation in the ‘wounds and bleeding’ and ‘sea lice’ indices values, suggesting that these indices could be omitted from future assessments under similar conditions. On the contrary, the ‘activity and stimuli’ index would be a cost-effective method for assessing the general condition of an animal in order to predict subsequent events in its life. For example, release condition (an index comparable to the activity and stimuli' index) was one of the best and most consistent predictors of the PCS of tropical reef fish and at the same time simple enough to be used by recreational fishers for a broad assessment of species."

The study makes concluding remarks: 

"A very large proportion of chondrichthyan global catches is discarded [5], [52] though little is known about the fate of discarded individuals. Hence, PCS information is rarely considered as part of the strategies addressing the management of discarded chondrichthyan species. Given that chondrichthyans remain a low priority for fishery management agencies in general, cost- and labour-intensive research on the broad range of species taken in commercial fisheries may not be conducted in the short term. However, the current change in natural resource management objectives from single-species to ecosystem-wide objectives warrants a multi-species assessment of PCS. Yet multi-species assessments are more difficult, and finding more cost-effective and priority driven methods is important because chondrichthyans continue to be depleted and time and funding for comprehensive data collection is limited [30]. Our study provided species-specific estimates of PCS, showing that these estimates varied among species, but they were generally high for most discarded species. The risk-assessment approach is simple and easy to implement in the onboard observer programs currently monitoring commercial fisheries around the globe, allowing the identification of species of conservation concern, and the prioritization and better direction of research and conservation effort.