SPATIAL IMPLICATIONS OF A TEMPERATURE-BASED GROWTH-MODEL FOR ATLANTICCOD (GADUS-MORHUA) OFF THE EASTERN COAST OF CANADA

Lengths at age of Atlantic cod (Gadus morhua) off the eastern coast of Canada vary up to three-fold among geographic regions, with Georges B ank and the southern Gulf of St. Lawrence being the regions of fastest and slowest growth, respectively. Colour-coded contour maps of length at ages 2-8 (n = 59 518) based on research vessel surveys between 197 1 and 1992 clearly showed the spatial variations in size at age. Corre sponding maps of July-September bottom water temperature appeared to r eflect relative growth rate, whereas those for depth did not. A polyno mial expansion of a temperature-based von Bertalanffy growth model app eared to fit the data well, with no residual patterns across most ages , lengths, temperatures, or years. Model predictions were also consist ent with reported lengths at age for cod in other regions and countrie s. Declines in bottom water temperature over the past 5-10 years appea r to be at least partly responsible for observed declines in size at a ge of the cod stock on the eastern Scotian Shelf.