Statistical considerations in the analysis of catch-at-age observations

. Statistical considerations in the analysis of catch-at-age observations. -J. Cons. int. Explor. Mer, 43: 83-90. Fishing mortality rates are described by a model encompassing common simplifying assumptions, including separable age and year effects, constant mortality rate above the age of full recruitment, and proportionality to a given fishing effort. Each of these assumptions can be tested against a more general specification. Because of the great difference in the catch numbers for different ages, transformations are necessary to stabilize variances, and care must be exercised so that large departures from normality do not invalidate inferences from the least-squares analysis