A method for estimating recruitment and mortality from time series of length-density data

Estimates of natural mortality are currently unavailable for Patagonian toothfish. Such estimates are needed for estimating recruitments and for use in assessing yield. This paper proposes a method for jointly estimating natural mortality and cohort strength at age 4 using a negative log-likelihood function based on one or more cohorts for which their abundance has been estimated in two or more years. A worked example is provided in an appendix.