DENSITY-DEPENDENT HABITAT SELECTION BY JUVENILE HADDOCK (MELANOGRAMMUS-AEGLEFINUS) ON THE SOUTHWESTERN SCOTIAN SHELF

Positive correlations between total abundance and indices representing distributional area have been reported for several marine fish stocks . Different indices can produce different results for the same stock a nd many indices scale positively with total abundance. We describe an alternative approach to modelling the distributional response to varia tion in total abundance using data for juvenile haddock (Melanogrammus aeglefinus) from the southwestern Scotian Shelf. Annual bottom trawl surveys having a stratified random design were used to estimate the lo cal density of haddock age 1 and 2 in each strata. Estimates of total abundance-at-age were obtained from sequential population analysis. Th e relationship between local density and total abundance-at-age was de scribed for each strata using an exponential model with a Poisson erro r structure. Systematic variation among strata in the model parameters was indicative of density-dependent habitat selection and supported a previous study showing a positive correlation between distributional area and total abundance. Density-dependent habitat selection by juven ile haddock did not generate correlations between mean length-at-age a nd total abundance-at-age because the proportional abundance of haddoc k in areas of differing growth rates remained approximately constant a s total abundance-at-age increased.