Loading...
Please wait, while we are loading the content...
Similar Documents
HUMPBACK WHALE (Megaptera novaeangliae): North Atlantic Stock
| Content Provider | Semantic Scholar |
|---|---|
| Copyright Year | 1998 |
| Abstract | STOCK DEFINITION AND GEOGRAPHIC RANGE In the western North Atlantic, humpback whales feed during spring, summer and fall over a range which encompasses the eastern coast of the United States (including the Gulf of Maine), the Gulf of St Lawrence, Newfoundland/Labrador, and western Greenland (Katona and Beard, 1990). Other North Atlantic feeding grounds occur off Iceland and northern Norway, including off Bear Island and Jan Mayen (Christensen et al., 1992; Palsbøll et al., 1997). 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. 1993; Katona and Beard, 1990; Palsbøll et al. 1997, Stevick et al. 1998). A few whales of unknown northern origin migrate to the Cape Verde Islands (Reiner et al., 1996). In the West Indies, the majority of whales are found in the waters of the Dominican Republic, notably on Silver Bank, on Navidad Bank, and in Samana Bay (Balcomb and Nichols 1982, Whitehead and Moore 1982, Mattila et al. 1989, 1994). Humpback whales are also found at much lower densities throughout the remainder of the Antillean arc, from Puerto Rico to the coast of Venezuela (Winn et al. 1975, Levenson & Leapley 1978, Price 1985, Mattila and Clapham 1989). It is apparent that not all whales migrate to the West Indies every winter, and that significant numbers of animals are found in midand 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 these waters, feeding on herring (Clupea harengus), sand lance (Ammodytes dubius), and other small fishes. In the northern Gulf of Maine, euphausiids are also frequently taken (Paquet et al. 1997). Commercial depletion of herring and mackerel led to an increase in sand lance in the southwestern Gulf of Maine in the mid 1970s with a concurrent decrease in humpback whale abundance in the northern Gulf of Maine. Humpback whales were densest over the sandy shoals in the southwestern Gulf of Maine favored by the sand lance during much of the late 1970s and early 1980s, and humpback distribution appeared to have shifted to this area (Payne et al. 1986). An apparent reversal began in the mid 1980s, and herring and mackerel increased as sand lance again decreased (Fogarty et al. 1991). Humpback whale abundance in the northern Gulf of Maine increased dramatically during 1992-93 , along with a major influx of herring (P. Stevick, pers. comm.). Humpback whales were few in nearshore Massachusetts waters in the 1992-93 summer seasons. They were more abundant in the offshore waters of Cultivator Shoal and the Northeast Peak on Georges Bank, and on Jeffreys Ledge; these latter areas are more traditional locations of herring occurrence. In 1996 and 1997, sand lance, and thus humpback whales, were once again abundant in the Stellwagen Bank area. However, |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://storestuff.s3.amazonaws.com/13200_98872307_1?AWSAccessKeyId=AKIAJBNEEVWEAALCCECQ&Expires=1580526897&Signature=cSK88uaLpbqztYF1OgABSPERNp8%3D&response-content-disposition=attachment%3B+filename%3D%22ao1999whhb-gme-508.pdf%22%3B+filename*%3DUTF-8''ao1999whhb-gme-508.pdf |
| Alternate Webpage(s) | https://www.afsc.noaa.gov/nmml/PDF/sars/ao1999whhb-gme.pdf |
| Alternate Webpage(s) | http://www.afsc.noaa.gov/nmml/PDF/sars/ao1999whhb-gme.pdf |
| Alternate Webpage(s) | http://www.nmfs.noaa.gov/pr/pdfs/sars/ao1999whhb-gme.pdf |
| Alternate Webpage(s) | https://www.afsc.noaa.gov/nmml/PDF/sars/ao1998whhb-gme.pdf |
| Alternate Webpage(s) | http://www.nmfs.noaa.gov/pr/pdfs/sars/ao1998whhb-gme.pdf |
| Alternate Webpage(s) | http://www.afsc.noaa.gov/nmml/PDF/sars/ao1998whhb-gme.pdf |
| Alternate Webpage(s) | https://storestuff.s3.amazonaws.com/13200_98872305_1?AWSAccessKeyId=AKIAJBNEEVWEAALCCECQ&Expires=1580528915&Signature=S/ETasRvkTGoS/N3jJTIWWmUtcs%3D&response-content-disposition=attachment%3B+filename%3D%22ao1998whhb-gme-508.pdf%22%3B+filename*%3DUTF-8''ao1998whhb-gme-508.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
