Humpback whales, Megaptera novaeangliae, and other cetaceans on Virgin Bank and in the northern Leeward Islands, 1985 and 1986

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Abstract
Vessel surveys were conducted during the winters of 1985 and 1986 to investigate the abundance and distribution of humpback whales on Virgin Bank and in the northern Leeward Islands. Nonrandom track surveys conducted on Virgin Bank in 1986 produced observed densities ranging from 0 in late January and mid-March to 0.082 whales/naut. mi.2 (1 naut. mi. = 1.852 km) in mid and late February. The number of whales sighted per hour on Virgin Bank was similar for both 1985 and 1986, with a peak value of more than 1.3 whales/h in mid to late February. On Anguilla Bank, the number of whales sighted per hour ranged from 0 in late March to 0.66 in mid-February. Comparisons with data from Mona Passage, Puerto Rico, suggest a possible shift in abundance from east to west, with the peak abundance occurring in the second half of February on Virgin Bank and at the beginning of March in Puerto Rico. A total of 105 whales were individually identified during the study. Photographic matches demonstrate that Virgin Bank is used by whales from all of the major known western North Atlantic feeding grounds, and suggest that this may also be true of Anguilla Bank. Overall, the data suggest that Virgin Bank may be more important as a mating and calving ground than Mona Passage, Puerto Rico, but considerably less important than Silver Bank. Sightings of other cetacean species in the study area are summarized, and include observations of a minke whale (Balaenoptera acutorostrata) mother–calf pair on Anguilla Bank.