Aspects of spawner-recruit relationships, with particular reference to crustacean stocks: A review

Abstract

The fundamental biological issue for fisheries management is undoubtedly the prevention of recruitment overfishing, i.e. to prevent the spawning stock from being depleted by fishing to a level where it significantly reduces the abundance of recruits. However, for many important fisheries, particularly crustacean fisheries, the stock-recruitment relationship (SRR) is not known. In many cases, research on recruitment has concentrated on short-term studies of recruitment processes to the exclusion of research into the SRR which requires development of long term databases. This paper examines techniques required to model the SRR, using case studies from Western Australian crustacean fisheries. Outlines of potential problems such as errors and biases in the measurement of stock and recruitment indices, the time series nature of the data, and lack of stationarity in the data, are given with possible solutions. Environmental effects, which can greatly influence the abundance of recruits, may need to be determined before the underlying SRR can be seen. Some of the advantages and possible disadvantages of incorporating environmental variables in the SRR are examined. A thorough assessment of SRRs also involves a study of the impact of fishing on the stock and the effect of stochastic variation using simulations. The evaluation of the SRR requires a multi-disciplinary approach which includes the fields of biology, environment, economics, population dynamics and statistics.