REPRODUCTION 



Like many of the higher mammals, cetacean and pinniped females usually produce 

 one offspring per breeding cycle. This affords a high degree of protection 

 and parental care for developing young. Multiple births occur at a frequency 

 of about 1% or less for whales (Slijper 1962). The reproductive 

 characteristics of Maine's cetaceans and pinnipeds are quite diverse (table 

 13-5). All cetaceans and seals of coastal Maine mate in the water except gray 

 seals, which mate on land or in water. Both seal species exhibit delayed 

 implantation; cetaceans apparently do not. Cetaceans give birth to calves 

 underwater, whereas seals bear their pups on islands and ledges. Lactation is 

 comparatively prolonged in cetaceans (4 to 18 months) in contrast with Maine's 

 seals (1 to 2 months). 



Only the harbor seal is known to breed on islands and ledges along the coast 

 of Maine. Cetacean calves with their mothers have been sighted in coastal 

 Maine waters (harbor porpoise, humpback whale, right whale, and minke whale). 

 The nearest known major breeding ground for gray seals is Sable Island, Nova 

 Scotia, Canada. Minor breeding colonies exist at Grand Manan, New Brunswick, 

 Canada, and Muskeget Island, Massachusetts. Richardson's 1973 coastal 

 inventory of seal haulout sites revealed 58 sites (29%) with pups present. 

 Eleven of the 41 important haulout areas (26%) were judged to be significant 

 whelping sites (Richardson 1975). Six of these whelping areas are in region 

 5; three are in region 4 and one each in regions 1 and 2 (see appendix table 2 

 and atlas map 4) . Studies of the harbor seal populations of the west coast 

 and Sable Island, Canada, reveal a recruitment rate (pup production) of about 

 20% of the total post-whelping population (Richardson 1973b). Similar studies 

 have not been conducted on Maine harbor seal populations but a similar 

 recruitment is projected. 



FEEDING HABITS 



The majority of marine mammals in Maine are fish eaters (table 13-6). Those 

 fish most commonly eaten by cetaceans are schooling fishes, such as herring 

 and sand lance. Squid are an important food item for pilot whales and white- 

 sided dolphins and may determine local distributions of these whales. Only 

 the right whale is strictly a plankton feeder (copepods and euphausiids) . 

 Observations by Canadian investigators suggest that right whales exploit 

 euphausiids rather than copepods in the Bay of Fundy region (Gaskin et al. 

 1979). Most cetaceans are probably opportunistic and adaptable in their 

 feeding, taking any food items that are present in sufficient amounts (Katona 

 1977). Their mobility provides for even greater flexibility in food habits. 



Important feeding areas along the Maine coast are the upper portion of 

 Jeffreys Ledge, Columbia Ledge (Mt. Desert Rock region), Passamaquoddy Bay 

 (the approaches to the Bay of Fundy), and probably the mouths of most bays, 

 rivers, and estuaries. 



Gray seals and harbor seals largely feed on herring and flatfish. Work by 

 Mansfield and Beck (1977) in eastern Canada shows the percent occurrence of 

 different food items in gray seal and harbor seal stomachs (table 13-6). 

 Nonmigratory bottom fishes form the basic diet for most of the year; skates 

 and flounder for the gray seal and flounder and hake for the harbor seal. In 

 summer, however, large schools of fish and squid that migrate inshore form the 



13-11 



10-80 



