Precautionary Approach In Development Of A Directed Horse Clam FisheryIn British Columbia, Canada

Abstract

A directed fishery on horse clams is being developed in British Columbia, Canada. The paper describes how the development follows the guidelines of a framework, which explicitly endorses the precautionary approach. At the first phase of the development, biological and fisheries information on horse clams, such as longevity, reproductive characteristics, growth, mortality, and management schemes, was synthesised based on scientific literature, technical reports, and surveys. Growth parameters and natural mortality rates were estimated in the literature with certain degrees of uncertainties. At the second phase of the development, alternative management strategies were evaluated and a precautionary approach for setting up biological reference points was provided through a simulation study. A stochastic spawning stock biomass per recruit model was found to be able to fully utilise the available information. Uncertainties about the estimates of population parameters were incorporated in the simulation to produce a probability distribution of possible consequences in terms of reproduction potentials. After setting up a limit reference point, the fisheries managers are able to find from the probability distribution such an exploitation rate that the risk of reducing the reproduction potential below the limit reference point is small (e.g. 5%).