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Developing Biochemical and Physiological Predictors of Long Term Survival in Released Blue Sharks and Sea Turtles

Related PFRP projects:
Pop-Off Satellite Archival Tags to Chronicle the Survival and Movements of Blue Sharks Following Release from Longline Gear

Evaluating Biochemical and Physiological Predictors of Long Term Survival in Released Pacific Blue Marlin Tagged with Pop-up Satellite Archival Transmitters (PSATs)

Modeling the Eco-physiology of Pelagic Fishes and Sharks with Archival and Pop-up Satellite Archival Tags (PSATs)

Progress Reports (PDF): FY 2003, FY 2002, FY 2001

Project Overview
For catch-and-release sports fishing and non-retention of commercially caught non-target species to be justifiable management options, there must be a reasonable likelihood that released animals will survive long term. At present, there is no scientific basis for making this prediction for any large pelagic fish. Therefore, even when recreational anglers and commercial fishermen practice good catch-and-release fishing, high rates of delayed mortality are a distinct possibility. Tag-and-release programs are important tools for assessing post-release survival, but they can be difficult and expensive. Management strategies intended to minimize mortality of non-target species depend upon accurate information on post-release survival. Fisheries researchers recognize that many factors (e.g., size, sex, reproductive state, water temperature, fight time, fishing gear) may influence the likelihood of mortality. Consequently, conclusions from tag-and-release studies are rarely extrapolated to other species.

Rather than assessing how many fish survive, project investigators will research why fish die. Project researchers believe that delayed mortality is probably not a direct result of immediate metabolic pertubations but rather more likely due to irreversible cellular damage. Researchers will analyze tissue and blood samples from blue sharks and sea turtles to develop a set of diagnostic tools to assess the biochemical and physiological status of fish caught by longline gear on scientific cruises. Once a set of tools has been developed researchers will be in a position to use blood samples to assess a broad spectrum of parameters which collectively address the extent and nature of tissue damage in response to physiological stress of capture. These tools will be used in combination with pop-off satellite archival tag data to establish correlates of survival or mortality. Researchers plan to develop such tools to maximize lateral transfer between species and anticipate eventually applying these techniques on other commercially important game fish and non-target species.

Year 1 funding for this project received November 2000.