Is Overfishing of Atlantic Menhaden Taking Place?
The sensitivities examined in the recent update of the 2010 benchmark assessment of Atlantic menhaden are extended to include a case which combines estimable doming of the selectivities at age for both the reduction and bait fisheries, with a statistically defensible effective sample size for the catch-at-age term in the likelihood maximised in the fitting procedure for the Beaufort Assessment Model. The results are found to be preferred to the current Base case under the AIC model selection criterion, and indicate appreciably higher biomasses over recent years. F15% and F30% reference points are re-evaluated for both the Base case and this preferred sensitivity, with averaging of biological parameters over the past 10 years rather than the full period from 1955 to provide estimates more reflective of current conditions. The results indicate that in terms of the Base case, the fishing mortality F was below the F15% threshold for the first decade of the century, and furthermore that when selectivity doming is taken into account it was also below the F30% target level during this period.