Guillermo Diaz, Matthew Lauretta and Clay Porch

Session 5, Talk 1, 19/1/16 @ 0900 hrs

The International Commission for the Conservation of Atlantic Tunas (ICCAT) manages Atlantic bluefin tuna as two separate stocks: Western Atlantic, and Eastern Atlantic and Mediterranean separated by the 45^o West Longitude meridian.  The western Atlantic stock was last assessed in 2014 using a Virtual Population Analysis (VPA) assessment model and stock status was determined relative to MSY-related benchmarks.  A key factor in estimating these benchmarks is the highest level of recruitment that can be achieved in the long term.   Assuming that average recruitment cannot reach the high levels estimated to have occurred in the early 1970s (low recruitment potential scenario), F_2010-13 / F_MSY = 0.36 and SSB₂₀₁₃/SSB_MSY=2.25.  In contrast, estimates of stock status are more pessimistic under a high recruitment potential scenario with F_2010-13 / F_MSY = 0.88 and SSB₂₀₁₃/SSB_MSY=0.48.  ICCAT’s Standing Committee on Research and Statistics cautioned that the conclusions of the assessment do not capture the full degree of uncertainty in the assessment.  Some of the main unquantified uncertainties include mixing rates between the two stocks (the stock assessment was conducted assuming no mixing between stocks), recruitment levels (both recent and potential future levels), age of maturity, and age determination from length samples.  The ICCAT Atlantic-wide Bluefin Tuna Research Program is addressing many of these deficiencies.

Contact:  G. Diaz, Research Fishery Biologist, Southeast Fisheries Science Center (SWFSC), USA, This email address is being protected from spambots. You need JavaScript enabled to view it.