A review of elasmobranch catch-and-release science: synthesis of current knowledge, implications for best practice and future research directions

Abstract

Until relatively recently commercial fsheries have been considered the main driving factor for elasmobranch population declines. However, this belief has begun to shift with the realization that recreational elasmobranch catches may equal or exceed commercial catches in some regions. Many recreational angling fsheries for elasmobranchs involve high participation in catch-and-release angling practices. However, high release rates may not necessarily equate to high survival rates. Therefore, to assist accurate assessment of the potential impact of recreational angling on elasmobranchs, we attempted to summarize and integrate currently available information on specifc risk factors associated with recreational angling, alongside associated mortality rates, as well as information on angler behaviour as it relates to identifed risk factors. We categorized the major angling-related efects into two groups: injury-induced efects; and biochemical disruption-induced efects; providing a summary of each group and outlining the main lethal and sub-lethal outcomes stemming from these. These outcomes include immediate and delayed post-release mortality, behavioural recovery periods (which may in-turn confer increased predation risks), chronic health impacts and capture-induced parturition and abortion. Additionally, we detailed a range of angling practices and equipment, including hook-type, hook removal and emersion (i.e. air exposure), as well as inter- and intra-specifc factors, including aerobic scope, respiratory mode, body size and species-specifc behaviours, which are likely to infuence injury and/or mortality rates and should therefore be considered when assessing angling-related impacts. We then utilized these data to provide a range of actionable recommendations for both anglers and policymakers which would serve to reduce the population-level impact of recreational angling on these enigmatic animals.