Connecting post-release mortality to the physiological stress response of large coastal sharks in a commercial longline fishery

Details

• Journal Title:
  PLoS ONE
• Personal Author:
  Whitney, Nicholas M. ; Lear, Karissa O. ; Morris, John J. ; Hueter, Robert E. ; Carlson, John K. ; Marshall, Heather M.
• NOAA Program & Office:
  NMFS (National Marine Fisheries Service) ; SEFSC (Southeast Fisheries Science Center)
• Description:
  Bycatch mortality is a major factor contributing to shark population declines. Post-release mortality (PRM) is particularly difficult to quantify, limiting the accuracy of stock assessments. We paired blood-stress physiology with animal-borne accelerometers to quantify PRM rates of sharks caught in a commercial bottom longline fishery. Blood was sampled from the same individuals that were tagged, providing direct correlation between stress physiology and animal fate for sandbar (Carcharhinus plumbeus, N = 130), blacktip (C. limbatus, N = 105), tiger (Galeocerdo cuvier, N = 52), spinner (C. brevipinna, N = 14), and bull sharks (C. leucas, N = 14). PRM rates ranged from 2% and 3% PRM in tiger and sandbar sharks to 42% and 71% PRM in blacktip and spinner sharks, respectively. Decision trees based on blood values predicted mortality with >67% accuracy in blacktip and spinner sharks, and >99% accuracy in sandbar sharks. Ninety percent of PRM occurred within 5 h after release and 59% within 2 h. Blood physiology indicated that PRM was primarily associated with acidosis and increases in plasma potassium levels. Total fishing mortality reached 62% for blacktip and 89% for spinner sharks, which may be under-estimates given that some soak times were shortened to focus on PRM. Our findings suggest that no-take regulations may be beneficial for sandbar, tiger, and bull sharks, but less effective for more susceptible species such as blacktip and spinner sharks.
• Keywords:
  Bycatches (Fisheries) Longlines (Fishery Equipment) Mortality Sharks Longlines (Fishery Equipment)
• Source:
  PLoS ONE 16(9): e0255673
• DOI:
  https://doi.org/10.1371/journal.pone.0255673
• Document Type:
  Journal Article
• Funding:
  Grant no. NA13NMF4540056 ; Grant no. NA15NMF4540102 ; Grant no. NA14NMF4720320
• Rights Information:
  CC BY
• Compliance:
  Submitted
• Main Document Checksum:
  urn:sha256:ea9737bd708db486243fdbe605b95d7eaeb2ba83301486543c16255ad56d7fe3
• Download URL:
  https://repository.library.noaa.gov/view/noaa/45073/noaa_45073_DS1.pdf
• File Type:
  [PDF - 2.05 MB ]