Publication Abstract

Quantifying potential impacts of behavioural factors on crustacean stock monitoring and assessment: modelling and experimental approaches

Quantifying potential impacts of behavioural factors on crustacean stock monitoring and assessment: modelling and experimental approaches

J.T. Addison and R.C.A. Bannister

Catchability of crustaceans in trap fisheries is influenced by behavioral factors that may affect crustacean stock assessments. The likely impact of behavioral interactions is studied from three viewpoints. Firstly, from a theoretical viewpoint, standard assessment models are modified to include nonlinear relationships between fishing mortality and fishing effort and between catchability and abundance. The models predict that different conclusions would be reached about the level of nominal effort at which yield per recruit reaches a maximum (E_max) and hence about the degree of change resulting from changes in effort. When an asymptotic stock-recruitment curve is combined with a nonlinear fishing mortality - fishing effort relationship, the likelihood of stock collapse at high effort levels is changed. Secondly, experiments are described illustrating real behavioral effects. In these experiments, prestocking traps with one or more lobster or crab shows that lobster inhibit the entry of other lobster and crab and that crab inhibit other crab, but not lobster. These intra- and inter-specific effects reduced the catch rate of individual strings of traps by more than 50% in some cases. Finally, as a step towards aggregating the effect of behavioral interactions from the individual trap to the fishery level, we review recently developed modeling approaches explicitly incorporating entry and escape processes. The models provide a promising basis for describing the biological processes underlying the capture of lobster.

Reference:

J.T. Addison and R.C.A. Bannister, 1998. Quantifying potential impacts of behavioural factors on crustacean stock monitoring and assessment: modelling and experimental approaches. Canadian Special. Pubication on Fisheries and Aquatic Sciences, 125: 167-177

J.T. Addison* and R.C.A. Bannister*

Canadian Special. Pubication on Fisheries and Aquatic Sciences, 125: 167-177