NOTE Murphy: Occurrence and group characteristics of Balaenoptera acutorostrata 



581 



minke whale populations, including those elsewhere 

 in the North Atlantic. Data from Newfoundland, Ice- 

 land, and West Greenland show a similar seasonal 

 distribution in which minke whales arrive in spring, 

 are most abundant during mid- to late summer and 

 begin to leave in the autumn (Sergeant, 1963; 

 Mitchell and Kozicki, 1975; Kapel, 1980; Sigur- 

 jonsson, 1982). However, a few minke whales have 

 been reported off western Newfoundland and Iceland 

 in both November and December (Sergeant, 1963; 

 Sigurjonsson, 1982), and minke whales have occa- 

 sionally been caught off West Greenland between 

 November and February (Kapel, 1980). The same 

 seasonal occurrence is seen in the waters off Nor- 

 way and in the Arctic where a few whales have been 

 observed through the winter ( Jonsgard, 1951 ). High- 

 latitude areas of the North Pacific and the Antarctic 

 are also characterized by a seasonal distribution simi- 

 lar to that observed in the North Atlantic (Shimadzu, 

 1980; Dorsey, 1983; Gong, 1987; Stern, 1990). Since 

 most of these studies were not based on identified 

 individuals, it is not clear whether minke whales in 

 these areas are resident for long periods or whether 

 the reported sightings represent short-term occu- 

 pancy or transient passage by numerous animals. 



If the apparent decrease in abundance of minke 

 whales in Massachusetts Bay in autumn and winter 

 is, as suggested above, unrelated to effort, it may 

 reflect a migration of most minke whales to lower 

 latitudes at that time of year. Data on the winter 

 distribution of minke whales are scarce. In the south- 

 western North Atlantic, minke whales have been 

 reported in the waters between Bermuda and the 

 Antilles between the months of January and March 

 (Mitchell, 1991; Mattila and Clapham, 1989; Mattila 

 et al., in press). Stranding data show evidence of the 

 presence of minke whales in the waters off Florida 

 from December to February. 1 Winter sightings, while 



infrequent, have also been reported in the western 

 Gulf of Maine and in waters southeast of Cape Cod 

 (CeTAP 2 ). 



In the Southern Hemisphere, minke whales are 

 also reported in lower latitudes during the winter. 

 Off Brazil, as well as in the waters of the southwest- 

 ern Indian Ocean, minke whales are mainly present 

 in winter and spring (Williamson, 1975; Best, 1982). 

 However, some have been reported trapped in sea 

 ice in the Antarctic between May and October (Tay- 

 lor, 1957); this finding, together with year-round 

 sightings of minke whales in areas such as Califor- 

 nia (Stern, 1990), Greenland, Norway, and the Arc- 

 tic suggests that a few animals may overwinter at 

 higher latitudes. 



Calves 



During the fourteen years of this study only three 

 minke whale calves were observed. Sightings of 

 minke whale calves in high-latitude areas of the 

 North Atlantic are rare; this is not the case for cer- 

 tain other mysticetes (e.g. humpback whales 

 [Clapham and Mayo, 1987]; fin whales, Balaenoptera 

 physalus [Clapham and Seipt, 1991]; North Atlantic 

 right whales [Hamilton and Mayo, 1990]). Only two 

 minke whale calf sightings were reported in the 1982 

 Cetacean and Turtle Assessment Program (CeTAP) 

 study, both occurring just south of Cape Cod (one in 



1 Mead, J. Curator of marine mammals at the Smithsonian In- 

 stitution. Natl. Mus. Nat. History, Smithsonian Institution, 

 Washington, D.C. 20560. Unpubl. data, 1992. 



2 CeTAP (Cetacean and Turtle Assessment Program). 1982. Char- 

 acterization of marine mammals and turtles in the mid- and 

 North Atlantic areas of the U.S. Outer Continental Shelf. Final 

 Rep. of the Cetacean and Turtle Assessment Program, Univ. 

 Rhode Island, to the Bureau of Land Management, Washing- 

 ton, D.C. 



