The seafood industry must deal with the intrinsic variability that occurs within fish as a natural raw material and incorporate this variability into decision-making processes. Increased knowledge of the variability will allow both products and processes to be better designed and optimised. This will result in improved utilisation of limited fish resources, more consistent quality and increased yields. Hoki (Macruronus novaezelandiae) is New Zealand＇s largest fishing resource with a total allowable catch (TAC) of 250,000 metric tonnes per annum. The aim of this study was to measure the dimensions of hoki that are important for processing, namely weight, length, body thickness and body depth, and to develop models correlating these parameters so that one can then be predicted from another. The influence of the reproductive cycle (spawning) on these models, was also measured as the dimensions of spawning fish, especially larger individuals, were more variable and these individuals had a different body shape. These predictive models can be used to improve forecasting, processing operations and the consistency of product quality. (C) 2000 Elsevier Science Ltd. All rights reserved.