Full report - Conservation Gateway

Chapter 10 - Cetaceans© Claire Fackler/NOAA National Marine SanctuariesToothed WhalesAtlantic white-sided dolphinAtlantic white-sided dolphins display movement patternsthat appeared to vary greatly by season. Although whitesideddolphins were sighted in the Gulf of Maine, they migratedsouth in the winter months. Bycatch records showpresence of this species in the Mid-Atlantic Bight, but thespecies distribution in these areas was not well reflected inthis analysis because of the limited survey data (Figure 10-7a). In the spring and summer, Atlantic white-sided dolphinswere located throughout the Gulf of Maine, east ofLong Island, and east of Cape Cod to the eastern edge ofthe assessment boundary in high abundances (Figure 10-7b and 10-7c). Fall patterns showed sparsely distributedsightings throughout the Gulf of Maine (Figure 10-7d).Important Marine Areas for AtlanticWhite-sided DolphinGulf of Maine to the edge of Georges Bank, east ofLong Island; Not enough data to determine areas inthe Mid-Atlantic BightBottlenose DolphinThe data indicated that bottlenose dolphins are foundmostly offshore in the region, from the 100 m contour tothe Continental Shelf edge. In the winter, bottlenose dolphinswere present in the southern portion of the regionand along the Continental Shelf edge (Figure 10-8a). Inthe spring, summer, and fall, bottlenose dolphins werefound in high abundances along the shelf-slope break,with a clear area of mid- to high abundance at the mouthof Chesapeake Bay in the summer (Figure 10-8b, 10-8c,10-8d). Mid-Atlantic surveys have indicated that bottlenoseare also abundant in coastal areas of Virginia andNorth Carolina, especially in the winter when more thanhalf of the sightings were between the shoreline and 3 kmfrom shore (Barco et al. 1999; Torres et al. 2005).Important Marine Areas for BottlenoseDolphinThroughout the region from 100 m to theContinental Shelf edge, coastal and estuarineenvironments including the Chesapeake BayHarbor porpoiseDistinct distribution patterns vary greatly by season inharbor porpoise populations in the Northwest Atlantic.Similar to the Atlantic white-sided dolphin, harborporpoises migrated south in the winter months (Figure10-9a). Current survey effort does not capture their truedistribution in the southern portion of our region, but bycatchrecords have indicated the species is present. In thespring, harbor porpoises were distributed throughout theGulf of Maine and east and south of Long Island. Duringthe summer, harbor porpoises were concentrated in thenorthern part of the Gulf of Maine and the Bay of Fundyin high abundances. Fall patterns for harbor porpoisesshowed a coastal distribution in the Gulf of Maine withhigh abundances in the Bay of Fundy.Important Marine Areas for HarborPorpoiseGulf of Maine to the edge of Georges Bank, eastand south of Long Island; Not enough data todetermine areas in the Mid-Atlantic Bight10-12Northwest Atlantic Marine Ecoregional Assessment • Phase 1 Report