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Six species of pinnipeds and 13 species of cetaceans frequent the St. Lawrence, where their distribution is fairly uniform. In all, 18 species are found in the northern Gulf, compared with only 16 species in the estuary and on the Magdalen Shelf, due to the absence of the ringed and bearded seals. The beluga occurs only in the estuary and the Saguenay Fjord. Harbour and hooded seals have been occasionally recorded upstream of the estuary as far west as Montreal (Banfield 1977).
Presence of marine mammals in natural regions
|
| Species |
Priority rank |
Estuary |
North Shore |
Anticosti-East |
Channel |
Magdalen
Islands |
| Queb.¹ |
Contin.² |
X1 |
X3 |
X5 |
X2 |
X6 |
 |
| Pinnipedea |
| Harbour seal |
S4 |
G5 |
X |
X |
X |
X |
X |
| Grey seal |
S5 |
G4G5 |
X |
X |
X |
X |
X |
| Harp seal |
S5 |
G5 |
X |
X |
X |
X |
X |
| Hooded seal |
S5 |
G4G5 |
X |
X |
X |
X |
X |
| Ringed seal |
S5 |
G5 |
|
X |
X |
X |
|
| Bearded seal |
S5 |
G4G5 |
|
X |
X |
X |
|
|
| Cetaceans |
| Harbour purpoise |
S5 |
G5 |
X |
X |
X |
X |
X |
| Atlantic white-sided dolphin |
S4 |
G4 |
X |
X |
X |
X |
X |
| White-beaked dolphin |
S4 |
G4 |
X |
X |
X |
X |
X |
| Atlantic pilot whale |
S4 |
G5 |
X |
X |
X |
X |
X |
| Killer whale |
S4 |
G4G5 |
X |
X |
X |
X |
X |
| Beluga * † ‡ |
S3 |
G4T'Q |
X |
|
|
|
|
| Northern bottlenosed whale |
S3 |
G4 |
X |
X |
X |
X |
X |
| Sperm whale |
S4 |
G3G4 |
X |
X |
X |
X |
X |
| Minke whale |
S4 |
G5 |
X |
X |
X |
X |
X |
| Fin whale * † |
S4 |
G3G4 |
X |
X |
X |
X |
X |
| Blue whale * † |
S4 |
G2 |
X |
X |
X |
X |
X |
| Humpback whale * † |
S4 |
G3 |
X |
X |
X |
X |
X |
| Northern right whale * † |
S4 |
G1 |
|
X |
X |
X |
X |
Species in bold characters have a special conservation status
¹ Quebec priority rank according to CDPNQ (1999)
² North American priority rank according to The Nature Conservancy (1999)
* Species likely to be designated as threatened or vulnerable (Beaulieu 1992)
† Canada endangered species (Csemdc 1997)
‡ Priority species according to the St. Lawrence Vision 2000 species subcommittee |
The diversity and abundance of marine mammals are particularly high at the mouth of the Saguenay and along the Upper North Shore, due to the high biological productivity resulting from the upwelling of deep water at the head of the Laurentian Channel (Simard et al. 1986). This region is known as one of the best places in the world to observe cetaceans.
Listed species of marine mammals
Six species of marine mammals that frequent the St. Lawrence system have special conservation status: the beluga, northern bottlenosed whale, fin whale, blue whale, humpbacked whale and northern right whale. The northern bottlenosed whale is listed as an S3 species in Quebec, as is the beluga, which was also designated as a priority species by the St. Lawrence Vision 2000 species subcommittee. The northern right whale has the highest North American ranking due to its status as a endangered species, while the blue whale and humpback whale have received the North American G2 and G3 ratings respectively, which are given to species whose populations require special attention. Aside from the beluga, which is restricted to the estuary, and the northern right whale, which is absent from it, the other listed species can be observed in all the natural aquatic regions of the St. Lawrence. Except for the beluga, which is a year-round resident, these species all leave the St. Lawrence in winter for the eastern seaboard or southern oceans.
The beluga population that frequents the estuary has declined sharply in the last few decades. The dramatic decrease in this population was probably caused by overhunting in the early part of the century. Hunting was banned in the 1970s. Although the St. Lawrence beluga population is now stable or increasing slightly (Lesage and Kingsley 1998), its recovery is probably being hindered by the bioaccumulation of contaminants in the whales' tissues, which affects their reproduction, and by disturbances associated with whale watching and commercial shipping activities (St. Lawrence Beluga Recovery Team 1995).
Benoît Jobin and Jean-Luc DesGranges
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