An Assessment of Spatial Dynamics of Stock Structure for Three Gulf of Maine Groundfish Species

The Gulf of Maine Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus) and white hake (Urophycis tenuis) stocks have declined and show slow signs of recovery, despite efforts by the Northeast Fisheries Management Council to reduce fishing mortality since the 1990s. One hypothesis explaining the lack of accelerated recovery is that there is an inconsistency of spatial scales in fisheries management relative to the underlying ecological boundaries. Managing stocks consistent with the ecological scale of the fishery may have an important impact on the recoverability of the stocks. The objective of this study is to evaluate this hypothesis. We have evaluated spatial variation in the stock structure of these groundfish species - in the inshore waters of the Gulf of Maine, using an eight-year data set (2001-2008) from the Maine Department of Marine Resources inshore trawl survey. The biological parameters we examined include maturity ratio, size structure, sex ratio, and condition factors (weight to length ratios) in each of the study areas across the Gulf of Maine.  Spatial variation of biological parameters between study areas for these species suggests that management needs to adjust to appropriately accommodate the spatial variation in stock structure.