Proposal for a comprehensive assessment of key shark species SAR-8-15
-
Upload
herrod-hodges -
Category
Documents
-
view
23 -
download
0
description
Transcript of Proposal for a comprehensive assessment of key shark species SAR-8-15
![Page 1: Proposal for a comprehensive assessment of key shark species SAR-8-15](https://reader035.fdocuments.in/reader035/viewer/2022062720/56813419550346895d9b065a/html5/thumbnails/1.jpg)
Proposal for a comprehensive assessment of key shark
species
SAR-8-15
Photo: www.borutfurlan.com
![Page 2: Proposal for a comprehensive assessment of key shark species SAR-8-15](https://reader035.fdocuments.in/reader035/viewer/2022062720/56813419550346895d9b065a/html5/thumbnails/2.jpg)
Background• IATTC resolution C-05-03
– Requires IATTC, in cooperation with scientists of CPCs and, if possible, the Western and Central Pacific Fisheries Commission, to propose a research plan for comprehensive assessment of stock status of key shark species
• In the eastern Pacific, sharks are taken as catch/bycatch in: - purse-seine fishery- commercial longline fisheries- artisanal fisheries
• The IUCN Red List of Threatened species includes the two shark species thought to be most common in purse-seine bycatch:
- Silky shark (“Lower Risk”)- Oceanic whitetip shark (“Vulnerable”)
• Decreasing trends are observed for shark bycatch rates from the purse-seine fishery, but not in standardized CPUE data of the western Pacific longline fishery
![Page 3: Proposal for a comprehensive assessment of key shark species SAR-8-15](https://reader035.fdocuments.in/reader035/viewer/2022062720/56813419550346895d9b065a/html5/thumbnails/3.jpg)
Standardized silky shark bycatch per set (floating object sets)
![Page 4: Proposal for a comprehensive assessment of key shark species SAR-8-15](https://reader035.fdocuments.in/reader035/viewer/2022062720/56813419550346895d9b065a/html5/thumbnails/4.jpg)
Oceanic whitetip shark (floating object sets)
![Page 5: Proposal for a comprehensive assessment of key shark species SAR-8-15](https://reader035.fdocuments.in/reader035/viewer/2022062720/56813419550346895d9b065a/html5/thumbnails/5.jpg)
![Page 6: Proposal for a comprehensive assessment of key shark species SAR-8-15](https://reader035.fdocuments.in/reader035/viewer/2022062720/56813419550346895d9b065a/html5/thumbnails/6.jpg)
Assessment objectives
• Catalogue current knowledge relevant to an assessment
• Compile and analyze available fishery data– Catch, effort, CPUE, length frequency
• Establish research needs – Process of modeling highlights research needs (e.g.,
lack of information on stock structure, life history parameters)
• Determine population status
![Page 7: Proposal for a comprehensive assessment of key shark species SAR-8-15](https://reader035.fdocuments.in/reader035/viewer/2022062720/56813419550346895d9b065a/html5/thumbnails/7.jpg)
List of key species
• Proposed species based on involvement in pelagic fisheries, past & present:– Oceanic white tip (Carcharhinus longimanus)– Silky shark (C. falciformis)– Blue shark (Prionace glauca)– Shortfin mako (Isurus oxyrinchus)– Bigeye thresher (Alopias superciliosus)
• Other criteria to consider:– Availability of data– Predation on tunas– Potential vulnerability due to life history
![Page 8: Proposal for a comprehensive assessment of key shark species SAR-8-15](https://reader035.fdocuments.in/reader035/viewer/2022062720/56813419550346895d9b065a/html5/thumbnails/8.jpg)
Preliminary steps
• Gather and integrate information from different sources– Biological data: growth rates, L/W ratios, sex ratios, maturity,
fecundity, natural mortality– Fishery data: catch, effort, size/age structure of catch,
standardized CPUE
• Identify information gaps– Stock structure– Life history– Catch and catch rates
• Identify initial modeling approaches– Spatial structure / fisheries– Information gaps may require modified approaches by species
![Page 9: Proposal for a comprehensive assessment of key shark species SAR-8-15](https://reader035.fdocuments.in/reader035/viewer/2022062720/56813419550346895d9b065a/html5/thumbnails/9.jpg)
Necessary resources
• Additional (temporary) research staff support at the post-doctoral level:
- Ph.D.-level background in fisheries- to be assisted by IATTC staff and Dr. Minami (ISM, Tokyo)- could coordinate efforts with experts from national observer programs
• Any catch and effort data for fisheries that take sharks in the EPO
• Any unpublished life history data