HUMPBACK WHALE ( Megaptera novaeangliae ) : North Atlantic Stock

These six regions represent relatively discrete subpopulations, fidelity to which is determined matrilineally (Clapham and Mayo 1987). Recent genetic analysis of mitochondrial DNA (mtDNA) has indicated that this fidelity has persisted over an evolutionary timescale in at least the Icelandic and Norwegian feeding grounds (Palsbøll et al. 1995, Larsen et al. 1996). Genetic partitioning is not evident in the western North Atlantic, however; thus these four subpopulations (Gulf of Maine, Gulf of St Lawrence, Newfoundland/Labrador and western Greenland) are treated as a single stock in this report. However, given that fidelity to each feeding area is known to be high, it is possible that each of the four regions should be managed separately, an approach which requires further investigation. In winter, whales from all six feeding areas mate and calve primarily in the West Indies, where spatial and genetic mixing among subpopulations occurs (Clapham et al. It is apparent that not all whales migrate to the West Indies every winter, and that significant numbers of animals are found in mid-and high-latitude regions at this time (Swingle et al. 1993, Clapham et al. 1993). An increased number of sightings of young humpback whales in the vicinity of the Chesapeake and Delaware bays occurred in 1992 (Swingle et al. 1993). Wiley et al. (1995) reported 38 humpback whale strandings which occurred during 1985-1992 in the U.S. mid-Atlantic and southeastern states. Humpback whale strandings increased, particularly along the Virginia and North Carolina coasts, and most stranded animals were sexually immature; in addition, the small size of many of these whales strongly suggests that they had only recently separated from their mothers. Wiley et al. (1995) concluded that these areas are becoming an increasingly important habitat for juvenile humpback whales and that anthropogenic factors may negatively impact whales in this area. There have also been a number of wintertime humpback sightings in coastal waters of the southeastern U.S. (NMFS unpublished data; New England Aquarium unpublished data; Florida DEP, unpublished data). Whether the increased sightings represent a distributional change, or are simply due to an increase in sighting effort and/or whale abundance, is presently unknown. Feeding is the principal activity of humpback whales in New England waters, and their distribution in New England waters has been largely correlated to prey species and abundance, although behavior and bottom topography are factors in foraging strategy (Payne et al. 1986, 1990). Humpback whales are frequently piscivorus when in …