24 results

Next-generation Close-kin Mark Recapture: using SNPs to identify half-sibling pairs in Southern Bluefin Tuna and estimate abundance, mortality and selectivity

Project number: 2016-044
Project Status:
Completed
Budget expenditure: $328,743.00
Principal Investigator: Campbell Davies
Organisation: CSIRO Oceans and Atmosphere Hobart
Project start/end date: 2 Oct 2016 - 29 Apr 2018
Contact:
FRDC

Need

Annual estimates of SBT spawning stock abundance are required to assess the status and productivity of the stock. Prior to the original CKMR study, there was no direct index of abundance of the spawning population The majority of the difference in the estimates of spawning stock status between the 2011 and 2014 stock assessments was due to the influence of the CKMR data, in combination with the 1990’s conventional tagging data. This reduced the overall uncertainty in spawning biomass and natural mortality and, therefore, identified a number of unproductive (pessimistic) parameter combinations as implausible. These were removed from the reference set of OMs (Anon 2014)

The schedule of implementation of the CCSBT MP includes a full stock assessment is scheduled for 2017. As a result of decisions by CCSBT to discontinue the Aerial Survey and move to gene-tagging, the CCSBT will initiate development of a new MP in 2017. Candidate MPs will be tested (in 2018) and a final MP selected using the OMs reconditioned in 2017 as part of the full stock assessment. The aim of this FRDC project is to provide a time-series of absolute abundance estimates of spawning potential from 2002 to 2013 for direct use in the CCSBT OMs. This abundance trajectory of the spawning potential of the stock will be independent of CPUE and catch data from the main fisheries, and will be an important input to domestic and international consideration of the stock status and performance of the rebuilding plan.

If the CKMR information is not available for the 2017 assessment, it is highly unlikely to be incorporated for testing of Candidate MPs. This would mean the CCSBT MP used to recommend future global TACs would not be “calibrated” with the most recent information on the status and recent trend in the spawning stock.

Objectives

1. Process archived tissue samples, extract DNA and genotype (~16,000 individuals, 2006-2014)
2. Combine genotypes from 1 with those from related CCSBT project (2015-2016)
3. Estimate time series of total adult abundance, spawning potential and total mortality on the spawning population
4. Report outcomes to SBTMAC, AFMA and CCSBT Scientific Committee for incorporation into 2017 update of the CCSBT Operating Model.

Final report

ISBN: 978-1-925994-04-9
Author: Campbell Davies
Final Report • 2020-06-16 • 3.04 MB
2016-044-DLD.pdf

Summary

This report presents the results of the first application of Close-Kin Mark-Recapture (CKMR) using both Parent-Offspring Pairs (POP) and Half-sibling Pairs (HSP). This application to Southern Bluefin Tuna (SBT) has been successful, providing a decadal time series of absolute abundance, total mortality and selectivity of adults. The method and the results have been reviewed and accepted by the Scientific Committee of the Commission for the Conservation of

Project products

Film/Video • 2020-06-16

Summary

This research has provided the world’s first scientifically tested management procedure for Southern Blue Fin Tuna (SBT) using DNA sequencing and genetic tagging to manage stock levels and deliver significant economic benefits.
Resource list • 2020-06-16 • 82.79 KB
papers 2016-044.pdf

Summary

The following working papers from this project were submitted to the CCSBT
Industry
Environment
PROJECT NUMBER • 1997-111
PROJECT STATUS:
COMPLETED

Catch-at-age, age at first spawning, historical changes in growth, and natural mortality of SBT: an integrated study of key uncertainties in population biology and dynamics of SBT, based on direct estimates of age from otoliths

The CCSBT has recognized for a number of years that a better understanding of the population biology and demographics of southern bluefin tuna (SBT) is necessary for improved population modeling and stock assessments. In 1996, the CCSBT Scientific Committee identified three areas where our...
ORGANISATION:
CSIRO Oceans and Atmosphere Hobart
Environment
PROJECT NUMBER • 1998-205
PROJECT STATUS:
COMPLETED

Construction and evaluation of an underwater setting device to prevent accidental capture of seabirds on tuna longliners

Longline fishing is one of the world's major methods of catching fish (Lokkeborg 1999). Some seabirds, particularly albatrosses and petrels have learnt to take bait from longlines while the lines are being set and when doing so put themselves at risk. If they either swallow the hook or become...
ORGANISATION:
Parks and Wildlife Service Tasmania
Environment
PROJECT NUMBER • 2013-025
PROJECT STATUS:
COMPLETED

Assessing post-release survival of Southern Bluefin Tuna from recreational fishing

Southern Bluefin Tuna (SBT) are an important component of the recreational game fishery in Australia. Recreational fishers in waters around South Australia, Victoria, Tasmania and New South Wales catch this species seasonally. Each state respectively is responsible for the management of this...
ORGANISATION:
University of Tasmania (UTAS)
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