AN EMPIRICAL-STUDY OF VARIABILITY IN LENGTH-AT-AGE OF MARINE FISHES

Variability in length-at-age of marine species of fish was studied using age and growth data and population-specific life history and environmental parameters for 168 species in 50 families (458 records). The shapes of distributions, the magnitude of variability, the patterns of variability with age and size, and the degree of overlapping of distributions were investigated using simple as well as multivariate statistical methods. Departure from normality was a widespread phenomenon. The most important pattern of variability was an increase to a maximum at an intermediate age or size followed by a decrease. The degree of overlapping was generally high, with only one or two distributions not significantly overlapped in most cases. The implications of these results for length frequency analysis and other areas of fisheries are discussed.