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

Variability in length-at-age of marine species of fish was studied usi ng age and growth data and population-specific life history and enviro nmental parameters for 168 species in 50 families (458 records). The s hapes of distributions, the magnitude of variability, the patterns of variability with age and size, and the degree of overlapping of distri butions were investigated using simple as well as multivariate statist ical methods. Departure from normality was a widespread phenomenon. Th e most important pattern of variability was an increase to a maximum a t an intermediate age or size followed by a decrease. The degree of ov erlapping was generally high, with only one or two distributions not s ignificantly overlapped in most cases. The implications of these resul ts for length frequency analysis and other areas of fisheries are disc ussed.