Patterns in the annual weight increment for div. 2J+3KL cod and possible prediction for stock projection

Abstract

Sample body weight-at-age data for NAFO Divisions 2J+3KL cod (Gadus morhua) from research vessel surveys were examined. Considerable variability in annual weight increment was found. A general linear model containing division and age effects explained 36% of the variance in the logarithm of annual weight increment. The residuals from this model showed a temporal pattern which appears to correspond to changes in the area of the cold intermediate layer (<0°C), an indicator of the amount of cold water on the shelf. Including the area of the CIL resulted in a model which explained 41% of the variability in weight increments. This model predicted weight increment data not included in the fitting reasonably well. Consideration is given to whether a predictive model based on this relationship could be useful in stock projections.