Integrating biological and social information to inform responsible ractices for recreational shark fishing

It is generally accepted that commercial fishing is capable of adversely impacting many of the world's fish stocks. However, with widespread participation and advances in technology available to anglers modern recreational fishing is now capable of matching and even exceeding the impacts of commercial fisheries. Given that sharks are a popular target for recreational fishers around the world, the expansion of recreational fishing means that this activity poses a growing threat to shark populations. Many shark species are particularly vulnerable to overfishing due to their life history characteristics (long lived, slow growth, late to mature and low fecundity) and most populations for which data exist are in decline. As such there is need to better understand and mitigate the effects of recreational fishing on sharks. Catch-and-release is commonly promoted by fisheries managers and recreational fishers as a strategy to reduce the impact of recreational fishing on fish populations while maintaining fishing opportunities. However, post-release mortality and sub-lethal effects on growth and fitness can reduce the effectiveness of catch-and-release. Despite this, catch-and-release is often promoted with limited knowledge of how the target animals are affected or whether the practice will be adopted by the broader recreational fishing community. The long-term sustainability of recreational fisheries depends on management of both the biological resource and its human users. As such, understanding current attitudes and behaviours associated with recreational shark fishing and how sharks respond to capture and release in terms of physiology, injury and survival is critical to any future management efforts. The shortfin mako shark (Isurus oxyrinchus) is a species commonly targeted by recreational anglers in many parts of the developed world. After a controversial political debate in Australia, only recreational anglers are currently permitted to target the species, contingent on the assumption that most are released and populations remain minimally impacted. The present study used the recreational fishery for shortfin mako shark as a case study of responsible recreational shark fishing due to the socio-political climate surrounding this species, its popularity as a game-fishing target and its dynamic ecological and physiological attributes. The thesis focused on three areas: (1) post-release survival and physiological stress response to capture of recreationally caught shortfin mako; (2) catch-and-release participation and the factors that may influence this behaviour; and (3) how gear choices and fishing behaviours relate to angler beliefs on sharks, their fishing impacts and their support for management. The study was based across three south-eastern Australian states; Tasmania, Victoria and New South Wales with the overall aim of integrating physiological and human dimensions research to inform and promote responsible fishing behaviour. Using satellite tags and blood based physiological analyses, it was found that fight times did elicit a physiological response to capture, characterised by increased plasma lactate with longer fight times; however the shortfin mako was resilient to these effects and all individuals that were angled in excess of 30 minutes survived. Subsequently, following a range of short and long fight times, the shortfin mako had a high (90%) overall rate of survival after release. Mortalities that did occur appeared to be linked to physical injuries caused by hooking, rather than physiological perturbations. The study provided evidence that circle hooks could reduce the chance of these injuries occurring. The human element of recreational fisheries was investigated by utilising an online questionnaire directed towards fishers who had caught, or targeted mako sharks in the previous year. Survey respondents reported releasing approximately 70% of shortfin mako sharks that they had caught in the 12 months prior to the survey, although release rates were found to vary based on the state of residence. Differences in catch-and-release participation can be attributed to the varying values that individual respondents placed on shortfin mako as a sport fish and/or table fish, the opportunity for resource substitution (alternative target species) and the established norms driven by current catch-and-release practices in each state. Although members of game fishing clubs were found to be more specialised than non-members, there were no differences between these groups in the practice of catch-and-release fishing. Many anglers use J hooks when intending to retain or release sharks despite positive perceptions with regard to how circle hooks can reduce the incidence of deep hooking and hence post-release mortality. Anglers generally did not accept, or were unaware of any negative impacts of recreational fishing on the status of the mako population. Logically, widespread adoption of responsible fishing behaviours will not occur if there is a failure by anglers to acknowledge and take responsibility for the impacts of their fishing and as such, some fishers did not see a need to modify their behaviours. This perception was particularly evident when commercial fisheries are perceived to have such a comparatively large impact. Overall differences in anglers' gear use and attitudes surrounding fisheries and fisheries management were found to be most significantly related to their state of residence, suggesting that any management or education initiatives need to take these differences into account. The uptake and utilisation of responsible fishing behaviours by the recreational fishing community is essential to the future sustainability of recreational fishing around the globe. For shark fishing, advice is provided in the form of best practices, on how to minimise physiological stress and physical injury, and reduce impacts on the environment, shark populations and bycatch. Recommendations on humanely slaughtering sharks are also discussed. Shark conservation efforts, including the adoption of responsible fishing practices can be hindered by a range of practical and attitudinal impediments that may be managed by improved education and outreach efforts. However, there is a need for more focus to be placed on effectively delivering this information to such a diverse group of resource users. Contemporary resource management requires fisheries to be treated as complex and adaptive social-ecological systems and in achieving this there is a growing need for interdisciplinary research. This thesis has examined both the fish and the fisher to paint a holistic picture of modern shark recreational fisheries and provide valuable information which can be used in the formation of responsible fishing practices.

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