Meta-analysis of changing spatial distribution of Northwest Atlantic fish stocks in relation to temperature and stock structure

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Ecosystem-based approaches to fisheries management require that we consider a broader set of considerations in how we manage our natural resources. This includes not only incorporating changing spatial distribution into assessments at the stock level, but also understanding changes in spatial characteristics of multiple species in relation to each other. We used several techniques to analyze trends in the mean centroid of abundance, mean depth, and population density for 36 fish stocks using the NMFS trawl survey data from 1968 to 2007. We identified several trends that are consistent with a response to the observed recent warming of Northwest Atlantic water temperatures. The center of abundance of numerous fish and invertebrate species has shifted to more northern latitudes in recent years. The range of some southern species has expanded while that of some northern species has become more restricted. Some species exhibit inshore/offshore shifts and have changed depth distribution. In contrast to these trends in distribution, some species such as winter skate and spiny dogfish appear to have shifted their distribution to more southerly waters. Depending on the stock, changes in distribution may be correlated with concomitant changes in temperature, abundance and/or size structure over time. We examine the management consequences of such movements in more detail for representative species.