Optimizing yields of the king mackerel (Scomberomus cavalla) fishery from the West and southern Gulf of Mexico

Abstract

The concept of optimum yield is applied to an age structured simulation model of the Scomberomorus cavalla (Mitchill) fishery in the western and southern Gulf of Mexico. Current yearly catch amounts to 2,600 tonnes and is part of a beach seine multispecies fishery yielding more than 10,000 tonnes annually. Cohort sizes and population parameter changes (fishing mortality and recruit numbers) were analyzed throughout a 39-year period. As a result of recruitment pattern, it was found that optimum yield can be attained when fishing mortality is F= 0.4, regardless of the population size. Hypothesizing that the stock fished along the Mexican coasts is independent from others of the same species caught elsewhere, it is concluded that the fishery has been overexploited since 1979. Yields obtained after simulations of the fishery applying several fishing intensities lead to the conclusion that the optimum yield level of about 3,000 tonnes could be achieved in the long term if the former fishing mortality value is applied, but this would imply a reduction of fishing effort to about 40 per cent below the current level.