Jon Brodziak, Hui-Hua Lee, Marc Mangel
03/28/2011 09:00 AM
Applied Mathematics & Statistics
We applied a new method to estimate probable values of stock-recruitment steepness for a Beverton-Holt recruitment curve for North Pacific albacore. We used information on growth, maturity at age, weight at length, natural mortality and reproductive ecology of albacore tuna and a simulation method to obtain the probability distribution of steepness. Thus, the results suggested that the North Pacific albacore tuna stock had a resilient to highly resilient stockâ€recruitment relationship depending upon the choice of growth curve. The results also conformed to the expectation that faster somatic growth, as indicated by higher values of the von Bertalanffy k parameter, was associated with higher resilience in the stockâ€recruitment relationship. Overall, the results indicated that the mean steepness of North Pacific albacore was less than unity. In this context, assuming that mean steepness is unity is a biologically implausible assumption because such an assumtpion implies that there is an infinite amount of compensation in the stockâ€recruitment relationship.
