Shifts in Species Distributions Associated with Climate Change

Shifts in distribution of a substantial number of fish and invertebrate species in the Mid-Atlantic region have been documented based on long-term datasets from research vessel surveys conducted by state and federal resource agencies. Within the region, a significant number of species have moved poleward and/or to deeper water (Nye et al. 2009, Lucey and Nye 2010). These changes have been connected to increasing water temperatures but in some cases (e.g., summer flounder) have also been linked to changes in the age and size composition of the stock and reflect shifts in distribution related to different species movement patterns (Link et al. 2015).

Climate is also changing the distribution of fish larvae, as well as the timing and location of spawning (Walsh et al. 2015). Butterfish and Atlantic mackerel are two species that have shifted in an opposite direction in the Mid-Atlantic Bight – towards shore rather than northward (Walsh et al. 2015). As bottom water temperatures have increased, there is clear evidence that surf clams (an important fishery in the Mid-Atlantic) have shifted into deeper waters at the southern extent of their range (Weinberg et al. 2005). The NOAA Northeast Fisheries Science Center has developed map products that display these findings, including the movement of species along the shelf and across the shelf through time, changes to the location of population cores through time, and animations of changes in abundance through time.

The impacts of other human stressors (historical and present) can complicate the measurement and monitoring of shifts in species distributions because they can confound any clear trends. Studies at the global scale predict that marine biodiversity could be redistributed to different areas within the worlds’ oceans, rather than lost (Molinos et al. 2015).