2016 SoE Marine Chapter - State and Trends - Tuna and billfish

The Marine chapter of the 2016 State of the Environment (SoE) report incorporates multiple expert templates developed from streams of marine data. This metadata record describes the Expert Assessment "The state and trends of quality of species and groups – tuna and billfish". The full Expert Assessment, including figures and tables (where provided), is attached to this record. Where available, the Data Stream(s) used to generate this Expert Assessment are accessible through the "On-line Resources" section of this record.

DESCRIPTION OF TAXONOMIC GROUP FOR EXPERT ASSESSMENT
This assessment focuses on those tuna and billfish species that are targeted by commercial fisheries and for which stock assessments are available. These include albacore, bigeye, skipjack, southern bluefin and yellowfin tuna, broadbill swordfish and striped and blue marlin. 
In Australian waters, southern bluefin tuna are caught predominantly by commercial fisheries in the south-west and temperate east bioregions with recreational catches also occurring in the north-west and south-east bioregions. Yellowfin, bigeye and albacore tuna, swordfish and striped marlin are predominantly caught by commercial and recreational fisheries in the north-west, south-west, temperate east and north east bioregions with recreational catches also occurring in the north and in the south-east seasonally. Blue marlin is caught recreationally in the north-east, temperate east, south-west and north-west bioregions with commercial catches of the species not permitted 
DATA STREAM(S) USED IN EXPERT ASSESSMENT
The assessment is based on stock assessment information produced in working papers provided to the scientific committees of relevant RFMOs and annual reports of the scientific committees and working groups of relevant RFMOs. Assessments are based on a variety of data relating to species population dynamics, spatial dynamics, fishery catches, survey and mark-recapture experiments covering the spatial area of each of the RFMOs and spanning varying temporal periods. Details on the specific data products used in this assessment have not been provided.

2016 SOE ASSESSMENT SUMMARY [see attached Expert Assessment for full details]
• 2016 •
Assessment grade: Good
Assessment trend: Stable
Confidence grade: Adequate high quality evidence and high level of consensus
Confidence trend: Adequate high quality evidence and high level of consensus
Comparability: Grade and trend are notcomparable to the 2011 assessment
• 2011 •
Assessment grade: Good
Assessment trend: Stable
Confidence grade: Limited evidence or limited consensus
Confidence trend: Limited evidence or limited consensus

CHANGES SINCE 2011 SOE ASSESSMENT
Since the 2011 chapter, some management frameworks have been modified so both reporting and assessment frameworks have been altered providing clearer views of current stock status. The 2011 assessment doesn’t appear to have referenced available stock assessments which provide the best and most robust indications of status for each of the species. The 2011 assessment stated that there was limited evidence and limited consensus and that the condition of stocks in the south-west was poor and declining, which doesn’t reflect stock assessments conducted at the time. Since the 2011 assessment, stock assessments available for the species have been updated and new data streams are contributing to stock assessments.

Tags: billfish, expert assessment, fisheries management, population status, tuna
Organization: Australian Ocean Data Network