Fin whale (Balaenoptera physalus) COSEWIC assessment and status report: chapter 6

Habitat

Habitat considerations for baleen whales must consider all aspects of the species’ life history including: summer foraging grounds, winter calving and mating grounds, year round resident populations, and any specific requirements of the various age or sex classes. Unfortunately, the majority of information on fin whales is for summer feeding grounds. Little information is available on where they spend their winter months, or about the location of calving or breeding areas (Reeves et al. 2002), but see Migration.

Fin whales appear to use both coasts extensively during summer. While populations on both coasts appear to move offshore and possibly southward in winter, they are not completely absent from Canadian waters in winter (see Migration).

Habitat requirements

The summer habitat of fin whales tends to consist of areas with dense prey concentrations (Kawamura 1980, Gaskin 1982). Woodley (1996) found that in the Bay of Fundy, fin whales occurred primarily in shallow areas with high topographic relief, and their occurrence was correlated with herring and euphausiid concentrations.

Fin whale distribution is associated with low surface temperatures off the northeastern US and in the Bay of Fundy during summer months (Woodley and Gaskin 1996). Hain et al. (1992) documented an association with oceanic fronts, areas known for high biological productivity (Herman et al. 1981).

Gaskin (1983) noted that there are ample year-round food supplies for fin whales in the eastern Nova Scotia region. This is consistent with Brodie’s (1975) year-round observations of fin whales in this region, and with more recent reports of fin whales feeding on herring off Chebucto Head, Nova Scotia, especially in winter (H. Whitehead, unpublished data).

In the St. Lawrence estuary, conditions at the head of the St. Lawrence channel are ideal for concentrating euphausiids. This area forms a seasonal foraging habitat for many marine mammals including fin whales (Simard and Lavoie 1999).

Gregr and Trites (2001) proposed that oceanographic conditions off the north end of Vancouver Island create suitable conditions for the entrainment of phytoplankton and zooplankton. These conditions include the transport of primary production from upwelled areas further south, the wash-out of zooplankton from the continental shelf, and the confluence of major currents creating entrainment features such as fronts and eddies.

Trends

Describing the change in habitat over time for a migratory, pelagic species living in a fluid environment is difficult. Fin whales appear physically capable of searching widely for habitat patches. Thus, localized changes in habitat quality may alter the spatial distribution of the species but not reduce the total amount of habitat available. Changes in total amount of habitat available are more likely to be a function of basin-wide trends in productivity. Changes in fin whale habitat quality or availability will also be a function of the trophic interactions between fin whales, their prey, and their competitors.

Habitat protection/ownership

On both the Pacific and Atlantic coasts of North America, portions of the species’ range fall within the Exclusive Economic Zones of the United States and Canada. In both countries, marine mammals are protected from deliberate disturbance, and consequently this likely provides some degree of habitat protection in some areas (see Existing Protection or Other Status).

Explicit habitat protection is provided only by the recently designated Gully Marine Protected Area (MPA). The fin whale is one of the many species that use the area (Hooker et al. 1999). This area is very small relative to the fin whale’s extensive range.

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