PAYNE ET AL.: DISTRIBUTION OF HUMPBACK WHALE 



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Georges Bank 

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STRATIFIED MEAN SAND EEL PER TOW (LOG) 



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Figure 2— The regression and correlation coefficient (r) between 

 the stratified mean number of sand eel/tow (log value) and the 

 number of humpback whales/effort x 10 ~ 2 by region and year on 

 Georges Bank (closed circles) and in the Gulf of Maine (open cir- 

 cles). 



observed distribution of the humpback whale was 

 due to the distribution of sand eel. 



However, the correlation between the observed 

 number of humpbacks/effort and the log mean num- 

 ber of sand eel/tow by region on Georges Bank (Fig. 

 2) was not significant (r = 0.24, df = 18). The mean 

 number of sand eel/tow (log value) on Georges Bank 

 was greatest on the shallow shoals. Only one hump- 

 back whale was observed on the shoals between 

 1978 and 1982. Our data does not support any 

 co-occurrance between humpback whale distribution 

 and sand eel abundance on Georges Bank despite 

 dense patches of sand eel in that region. 



DISCUSSION 



Our data suggest that the distribution of hump- 

 back whales in the Gulf of Maine-Georges Bank 

 region is presently centered in the southwest Gulf 

 of Maine. This distribution is correlated with dense 

 concentrations of sand eel, a principal prey item, 

 which has dramatically increased throughout shelf 



waters of the eastern United States including the 

 southwest Gulf of Maine since the mid-1970's (Meyer 

 et al. 1979; Sherman et al. 1981). This increase in 

 sand eel followed a decline of Atlantic herring stocks 

 from the mid-1960's to the mid-1970's (Anthony and 

 Waring 1980; Grosslein et al. 1980), and possible 

 replacement by sand eel of depleted fish stocks in 

 the northwest Atlantic (Sherman et al. 1981). The 

 correlations between the humpback distribution in 

 the Gulf of Maine and sand eel abundance supports 

 the theory by Kenney et al. (1981) that the present 

 distribution of the whales in that region is due to 

 the distribution of sand eel. A demonstrated shift 

 in the humpback distribution since the mid-1970's 

 from the upper Gulf of Maine-lower Bay of Fundy 

 southward into the southwest Gulf of Maine also 

 supports this theory. 



A 10-yr summary of observations from Mt. Desert- 

 Rock, ME (MDR, Fig. 1) in the northern Gulf of 

 Maine shows a dramatic decrease in the number of 

 humpback sightings/observer hour since 1977 (Mul- 

 lane and Rivers 1982). The maximum number of 

 humpbacks observed in that summary occurred in 

 1975 (98 whale sightings, 0.123 humpbacks/observer 

 hour). Only 10 humpbacks were seen from 1978 to 

 1982, and the maximum number of humpbacks/ef- 

 fort since 1975 has been 0.005/observer hour in 

 1982. This decline in the number of humpbacks at 

 MDR coincides with the increased numbers of hump- 

 backs observed in the southwest Gulf of Maine. 

 Twelve of the 17 humpbacks photo-identified from 

 1975 to 1977 at MDR have subsequently been seen 

 in the southwest Gulf of Maine, principally on Stell- 

 wagen Bank. At least three of these whales have 

 been observed during three different years on Stell- 

 wagen Bank since they were first identified at MDR 

 (Mullane and Rivers 1982). In comparison, only one 

 whale identified at MDR has consistently returned 

 to the coastal waters of eastern Maine and New 

 Brunswick. Katona et al. (1977) also listed the Grand 

 Manan Banks, Briers Island-St. Mary's Bay, Nova 

 Scotia, and the lower Bay of Fundy as areas of 

 humpback congregations. However, humpbacks 

 were not common in the Bay of Fundy during 1981 

 and 1982 (Kraus and Prescott 1981, 1982). 



Shifts in the distribution of humpbacks caused by 

 changes in the distribution and density of prey 

 species have been shown elsewhere (Lien and Merd- 

 soy 1979; Whitehead et al. 1980). We believe that 

 the correlations between humpbacks/effort and 

 mean sand eel catches in the southwest Gulf of 

 Maine, and the demonstrated decline of humpbacks 

 throughout the upper Gulf of Maine-lower Bay of 

 Fundy concurrent with an increase in the numbers 



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