Estimation of Mortality Rates of Female Swimming Crab Portunus tribuberculatus Meirs from Single-release Marking Studies

Abstract

This paper describes a field study to estimate instantaneous fishing and natural mortality rates of swimming crab from mark recoveries, denoted by F and M, respectively. Efforts are made to eliminate systematic errors which influence estimates. Paint marks on the carapace of mated or egg-holding female crab are assured to be retained for a research period from May through July. The observation is censored at 60 days after release. The goodness of fit of the theoretical model to the recovery data is considered and estimates of Fand M are obtained. It is concluded that natural mortality of the crab is small and fishing mortality is large in Hiuchi-Nada area. © 1990, The Japanese Society of Fisheries Science. All rights reserved.