ABSTRACT 



Sightings of 56 species of marine birds and 11 species of marine mammals 

 recorded from 1971 - 1977 are summarized to show species composition and 

 spatial and temporal distribution over the Continental Shelf in the northern 

 Chesapeake Bight. Distributional abundance of seabirds is indicated relative 

 to sounding contours and to the average distance from shore. Cetaceans and 

 pelagic birds are most abundant between the 30 and 40- fathom contour and 

 along the edge of the Continental Shelf, especially Baltimore Canyon. Gulls 

 of the genus Larus composed 71.8% of the offshore avifauna from November 

 through March. Wilson's storm petrel ( Oceanites oceanicus ) accounted for 

 66.6% of all seabirds counted from May through September. Fishing vessel 

 activity was responsible for winter seabird concentrations. Distribution of 

 tropical and subtropical seabirds and cetaceans corresponds to the presence of 

 warm slope water and Gulf Stream eddies spreading over the outer Continental 

 Shelf during late summer months. The northern fulmar ( Fulmarus glacial is ) and 

 Manx shearwater ( Puffin us puffinus ) may be extending their ranges and increas- 

 ing in abundance in the western North Atlantic. Most cetacean sightings were 

 seaward of the 20-fathom contour. The saddleback dolphin ( Delphinus del phis ) 

 is the most common offshore cetacean. Grampuses (G rampus griseus ) are often 

 seen along the Continental Slope and in Baltimore Canyon. One population of 

 Atlantic bottlenosed dolphins ( Tursions truncatus) occurs offshore along the 

 Continental Slope, and another is usually found within 10,000 m offshore. A 

 small population of fin whales ( Balaenoptera physalus ) resides over the Conti- 

 nental Shelf in the northern Chesapeake Bight. Fin whales and saddleback 

 dolphins were most abundant each spring at about 38°15'N, between the 30 and 

 40-fathom contour. 



The correct citation for this report is: 



Rowlett, Richard A. 1980. Observations of marine birds and mammals in 

 the northern Chesapeake Bight. U.S. Fish and Wildlife Service, Biological 

 Services Program. FWS/OBS-80/04. February 1980. 87 pp. 



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