THE DISTRIBUTION OF THE HUMPBACK WHALE, 



MEGAPTERA NOVAEANGLIAE, ON GEORGES BANK AND IN 



THE GULF OF MAINE IN RELATION TO DENSITIES OF 



THE SAND EEL, AMMODYTES AMERICANUS 



P. Michael Payne, 1 John R. Nicolas, 2 Loretta O'Brien, 2 

 and Kevin D. Powers 1 



ABSTRACT 



The distribution of the humpback whale, Megaptera novaeangliae, (based on shipboard sighting data) is 

 significantly correlated (r = 0.81, df = 13) with the number of sand eel, Ammodytes americanus, per 

 standardized tow (based on NMFS/NEFC groundfish surveys) by strata within the Gulf of Maine A 

 demonstrated increase in the number of humpback whale sightings in the southwest Gulf of Maine since 

 1978 concurrent with an increase in the number of sand eel in the same area supports the hypothesis 

 that within the Gulf of Maine the present distribution of humpback whales is due to the distribution of 

 their apparent principal prey, the sand eel. A similar correlation between humpback whale sightings and 

 sand eel abundance on Georges Bank was not significant (r = 0.24, df = 18) despite dense patches of 

 sand eel in that region. Therefore, within the combined Gulf of Maine-Georges Bank regions, factors other 

 than simply prey availability must influence the feeding distribution of the humpback whale We argue 

 that the bottom topography of the Gulf of Maine and the foraging behavior of the whales are critical 

 factors influencing their present feeding distribution. 



In the northwest Atlantic, the major summer con- 

 centrations of humpback whales, Megaptera novae- 

 angliae, occur off the coasts of Newfoundland- 

 Labrador and off the coast of New England in the 

 Gulf of Maine which includes Georges Bank (Katona 

 et al. 1980; Whitehead et al. 1982). During this 

 period feeding is their principal activity. The major 

 winter concentrations in the western North Atlan- 

 tic occur along the Antillean Chain in the West 

 Indies, principally on Silver and Navidad Banks 

 which lie north of the Dominican Republic (Winn et 

 al. 1975; Balcomb and Nichols 1978; Whitehead and 

 Moore 1982). During this season conception and 

 calving are their primary activities; food does not 

 seem to be an important determinant of the hump- 

 backs in these areas (Whitehead and Moore 1982). 

 Humpbacks have been generally considered 

 coastal animals (Mackintosh 1965). However, their 

 migratory routes between regions of winter breed- 

 ing and summer feeding in the northwest Atlantic 

 (based on sighting data) occur in deeper, slope 

 waters off the continental shelf (Hain et al. 1981; 

 Kenney et al. 1981; Payne et al. 1984). Several possi- 

 ble offshore routes between winter and summer 

 grounds suggest reasonably distinct stocks (Katona 



^anomet Bird Observatory, Marine Mammal and Seabird 

 Studies, Box 936, Manomet, MA 02345. 



2 Northeast Fisheries Center Woods Hole Laboratory, National 

 Marine Fisheries Service, NOAA, Woods Hole, MA 02543. 



et al. 1980). Kenney et al. (1981) suggested that for 

 the Gulf of Maine stock, the Great South Channel 

 (Fig. 1) is the major exit-entry between the Gulf of 

 Maine feeding area and the deeper, offshore migra- 

 tion route. 



Humpback whales have been described as general- 

 ists in their feeding habits (Mitchell 1974). The 

 reported prey of humpbacks in the Gulf of Maine 

 are Atlantic herring, Clupea harengus; Atlantic 

 mackerel, Scomber scombrus; pollock, Pollachius 

 virens; and the American sand eel, Ammodytes 

 americanus (Gaskin 1976; Katona et al. 1977; 

 Watkins and Schevill 1979; Kraus and Prescott 

 1981). In recent years, observations of feeding 

 humpbacks indicate that sand eels have become an 

 increasingly important prey item in the Gulf of 

 Maine (Overholtz and Nicolas 1979; Hain et al. 1982; 

 Mayo 1982). 



Kenney et al. (1981) hypothesized that the ob- 

 served distribution of the Gulf of Maine humpback 

 stock was due to the distribution of sand eel, their 

 apparent principal prey species. However, the pres- 

 ent distribution of the humpback whale in the Gulf 

 of Maine and throughout the remaining shelf waters 

 of the northeastern United States is not so clearly 

 related to the distribution of sand eel as was sug- 

 gested. Although we recognize an important 

 predator-prey interaction between humpbacks and 

 sand eel, we hypothesize that behavior and bottom 



Manuscript accepted July 1985. 



FISHERY BULLETIN: VOL. 84, NO. 2, 1986. 



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