An assessment of the habitat quality and nutritional intake of North Atlantic right whales in Cape Cod Bay
Cape Cod Bay is the only known winter feeding ground of the North Atlantic right whale, a seriously endangered species, and is thus a critical habitat for right whales. As with most coastal ecosystems, Cape Cod Bay is a dynamic system with a high degree of variability in both physical and biological parameters. However, the extent of these fluctuations and their effect on the suitability of the bay as a right whale feeding ground is not known. This study was conducted to address variability in the biological and physical environment of the bay on different temporal and spatial scales and the possible impacts of this variability on the right whales' use of the area as a feeding ground and ultimately on the survival of this species.
This study synthesized data collected from January to May over a four-year period, 2000–2003. During the 2002 season, the whales had much more limited use of the bay compared to the other three years. Data collected during weekly cruises on the physical and biological environment of Cape Cod Bay data indicated that there was significant interannual variation in the wind forcing affecting Cape Cod Bay. Coincident with this variation were changes in the hydrography of the bay, suggesting that circulation patterns changed during the course of the study. These changes affected the zooplankton prey of the whales either directly through changes in advection or indirectly by affecting the production of the zooplankton.
Given the importance of the food resource in determining the presence of right whales in Cape Cod Bay, additional analyses explored the temporal and spatial variability in the zooplankton. There was a high degree of seasonal variability in the energetic value of the zooplankton available as a food resource for right whales. This variability was due in part to changes in species composition of the zooplankton assemblage as wells as to the variation over time within each stage of each species. Spatial variability was also significant as a result of the formation of dense aggregations of zooplankton.