von Bertalanffy stochastic differential equation growth model with multiplicative noise

AbstractThe well-known von Bertalanffy growth (VBG) model for estimating age-length relationship in fisheries is considered. Stochastic differential equation (SDE) approach is employed to take into account the effect of fluctuating environment. In this paper, the von Bertalanffy SDE (VBSDE) model with multiplicative noise is proposed. The resultant model is solved analytically. Relevant computer code for fitting the model is developed in SAS package and the same is added as an Appendix. Finally, as an illustration, superiority of our proposed model over VBSDE model with additive noise for fitting and forecasting purposes is shown for some fish data.