A stock reduction analysis of Bay of Plenty snapper

Abstract

A general approach to stock modelling of fisheries when information is scanty is proposed, in which all available relevant information is utilised and in which parameters are examined over feasible ranges. Using it, a new stock reduction analysis (SRA) is developed which is analytically simpler than those previously developed. All four factors of biomass change (recruitment, growth, natural mortality, and fishing mortality) are model inputs. The growth factor is derived from length frequency samples and a growth curve. Feasible ranges for the parameters, together with ancillary information regarding the stock, define a feasible region on the parameter space. In this region maxima and minima for biomass, surplus production, and other variables are found. The model is applied to the snapper (Chrysophrys auratus) stock in Bay of Plenty, New Zealand.

Keywords:

• stock reduction analysis
• non‐equilibrium population model
• size specific vulnerability
• stock biomass estimation
• Chrysophrys auratus
• Bay of Plenty
• snapper
• modelling