Funded
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- Objectives
- Estimate age, growth, maturity, and fecundity of yellowfin from four distinct areas of the eastern Pacific for use in spatially-structured stock assessment models
- Background
- Current estimates of age, growth, maturity, and fecundity of yellowfin are based on otolith and ovarian tissue samples collected over 30 years ago.
- During 2009-2016 observers collected otolith and ovarian tissues samples at sea throughout the EPO
- Tagging and morphometrics data indicate there are multiple stocks of yellowfin in the EPO, probably with different life history characteristics
- Heavily-exploited fish stocks often show trends towards earlier maturation
- Relevance for management
- Spatially-structured stock assessments based on geographically-explicit life history parameters will provide a more accurate basis for the staff’s management advice
- Duration
- 5 years; initiated in 2017
- Workplan and status
- 2017-2022: Preparation and reading of otolith samples for age estimates
- 2018-2021: Preparation and reading of ovarian tissue samples for maturity and fecundity estimates
- 2019-2023: Analyses of age and growth and reproductive biology data, and preparation of manuscripts
- Deliverables
- Updated, geographically-explicit life-history parameters for use in spatiallystructured stock assessments
- Manuscripts for publication in scientific journals
- Updated date: 01 May 2022
- Progress summary for the reporting period
- Daily increment counts for 246 otoliths have been completed, 128 from the central offshore region and 118 from the central nearshore region.
- A general additive model was used to investigate whether differences in growth exists between those two regions.
- Microscopic slides of ovarian tissues from 1,756 fish from the four distinct areas have been prepared for reading.
- Fecundity estimates from 146 female yellowfin tuna have been completed.
- Fuller, D. and K. Schaefer. Abstract in Proceedings of the 69th annual tuna conference, 21-24 May 2018, Lake Arrowhead, USA
- Fuller, D. and K. Schaefer. Abstract in Report of the workshop on age and growth of bigeye and yellowfin tunas in the Pacific Ocean, 23-25 January 2019, La Jolla, USA
- Schaefer, K. M., and Fuller, D. W. 2022. Spatiotemporal variability in the reproductive biology of yellowfin tuna (Thunnus albacares) in the eastern Pacific Ocean. Fisheries Research, 248, 106225.
- Comments
- Access to the SWFSC due to the COVID- 19 pPandemic has slowed progress on preparation and reading of otoliths.