A Statistical Description of Recruitment in Eighteen Selected Fish Stocks

For understanding and predicting purposes, one is concerned with identifying suitable models and methods for describing empirical and theoretical relationships that may exist between fish stock, environment and recruitment. In this paper, recruitment in 18 fish stocks around the world is reviewed by examining the frequency distributions of observed year-class strength. These frequency distributions represent the probability density functions which incorporate the total effect of all factors. The actual frequency distributions of recruitment were plotted and each set of data tested for goodness-of-fit to normal and lognormal distributions. Conclusions from the tests were that most of the data sets could be described by a lognormal distribution function. Comparison of recruitment estimates and associated catches over time (years) indicated that significant deviations in catch closely followed significant deviations in recruitment. Serial correlation analyses of the recruitment data indicate, in most cases, that recruitment in 1 year is correlated with that of the previous year.