An integrated approach for assessing the survival of discarded sandbar sharks, Carcharhinus plumbeus, captured in scientific longlines

Authors

Taylor Grosse, Department of Primary Industries and Regional Development, Western AustraliaFollow
Cynthia Awruch, University of Tasmania
Euan S. Harvey, Curtin University
Benjamin J. Saunders, Curtin University
Chris Dowling, Department of Primary Industries and Regional Development, Western AustraliaFollow
Daniela Waltrick, Department of Primary Industries and Regional Development, Western AustraliaFollow
Matias Braccini, Department of Primary Industries and Regional DevelopmentFollow

Document Type

Article

Publication Date

11-27-2023

Journal Title

Marine and Freshwater Research

ISSN

ISSN: 1323-1650 eISSN: 1448-6059

Keywords

Chondrichthyes, fisheries, post-capture survival, post-release survival, PSAT tags, release condition, stress physiology, survivorship

Disciplines

Aquaculture and Fisheries

Abstract

Context

The sandbar shark (Carcharhinus plumbeus) has a global distribution and is caught by commercial fishers and recreational anglers. Aims

To assess the stress physiology, release condition, and post-release survival of sandbar sharks caught in longline surveys conducted in Western Australia. Methods

Post-release survival of sandbar sharks caught in longlining surveys was assessed using an integrated approach that combined the use of hook-timers, qualitative release conditions, satellite-tagging, and blood physiology. Key results

Of 57 individuals examined, there was 100% post-capture survival after a maximum of 4 h on the hook. Most of these animals (88%) displayed a strong release condition, exhibiting minimal behavioural impairment. All 13 satellite-tagged individuals survived 30 days post-capture. Sharks dived up to 307 m deep and showed cyclical depth movement patterns, with some individuals moving through the water column both day and night, whereas others moved almost exclusively at night. The concentration of blood metabolites did not significantly change with time-on-hook. Conclusion

Post-capture and post-release survival of 100% after up to 4 h on hooks suggested that the use of longlines for surveying sandbar shark abundance had no deleterious effects on captured sharks. Implication

This will support future stock assessments of sharks by quantifying the survival rates in the methods used for long-term monitoring of sandbar shark populations.

Recommended Citation

Grosse Taylor, Awruch Cynthia, Harvey Euan, Saunders Benjamin, Dowling Chris, Waltrick Daniela, Braccini Matias (2023) An integrated approach for assessing the survival of discarded sandbar sharks, Carcharhinus plumbeus, captured in scientific longlines. Marine and Freshwater Research 74, 1433-1444. https://doi.org/10.1071/MF22238