A CONTINUOUS FOX-FORM OF THE SURPLUS PRODUCTION OBSERVATION-ERROR ESTIMATOR

A surplus production model based on the Fox surplus production functio n is suggested, which differs from previous such models in that the co ntinuous, rather than discrete, form of the biomass dynamics equation is considered. The observation-error assumption is used to estimate th e parameters of this model. The Marquardt algorithm is used as the min imization scheme for this nonlinear model. The model is applied to New Zealand rock lobster and south Atlantic albacore fisheries. The valid ity of the model is tested by means of Monte-Carlo simulation method a nd the experiment population data sets of Silliman and Gutsell [Sillim an, R.P. and Gutsell, J.S., 1958. Experimental exploitation of fish po pulations. U.S. Fish. Wild. Serv. Fish. Bull. 58 (133), 215-252]. The simulations show that the estimator could provide approximate unbiased parameter estimates and have some ability to resist the disturbance o f stochastic errors. The model provides stable and relative accurate p arameter estimates for Silliman and Gutsell data. It also shows that t he model has relatively good predictive ability. (C) 1998 Published by Elsevier Science Ltd.