Local-Scale versus Large-Scale Factors Affecting Recruitment

Recent analyses of Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) stocks in the northwest Atlantic have indicated that large-scale factors (several hundred to thousands of kilometres) dominate over effects operating on more local scales (10 to a few hundred kilometres} in determining recruitment patterns for these stocks. Adding additional years and additional stocks to the data set, the recruitment time series for cod and haddock have been reexamined. A first differencing technique was used to remove trends in the data. The results indicate that while large-scale effects probably do affect recruitment, the dominant factors are operating on more local scales and correlations are strongest for neighboring stocks.