Fin whale (Balaenoptera physalus) COSEWIC assessment and status report: chapter 5

• Previous page
• Table of contents
• Next page

Distribution

Global range and stock structure

Fin whales are considered to have a cosmopolitan distribution (Figure 1) and can be found in all major oceans, although they are more abundant in temperate and polar latitudes (Leatherwood et al. 1988, Reeves et al. 2002). They are found in both coastal shelf waters and on the high seas (Jefferson et al. 1993). According to Aguilar (2002), the global density of fin whales is higher beyond the continental slope than closer to shore, and they appear to be absent at the ice edges and in most equatorial areas.

Cambell (1985) described a North Atlantic summer range extending to the Arctic, and a more widely dispersed winter range extending from the ice edge to the Caribbean. Rice (1998) described the summer range as extending from 75ºN in Baffin Bay and 80ºN in Spitsbergen, southward to 35ºN at Cape Hatteras, with animals sighted from the Grand Banks to the Gulf of Mexico in winter, while Mitchell (1974)suggested fin whales winter around 35ºN, between the North American coast and the continental shelf. The full extent of the summer and winter ranges of the species is poorly documented, likely due to the species’ pelagic nature (Notarbartolo-Di-Sciara et al. 2003).

In the North Pacific, the known summer range extends northward to 50ºN in the Sea of Okhotsk, 60ºN in the Bering Sea and 58ºN in the Gulf of Alaska, and southward to 40ºN in the Sea of Japan and 32ºN off the coast of California. The known winter range extends from Korea to Taiwan, the Hawaiian Islands and to the Baja California peninsula, although the distribution is believed to be primarily offshore (Leatherwood et al. 1988).

The IWC recognises seven stocks of fin whales in the North Atlantic (Donovan 1991), two of which--Newfoundland/Labrador and Nova Scotia--summer largely in Canadian waters. The U.S. National Marine Fisheries Service (NMFS) recognizes only a western North Atlantic stock in its territorial waters. While there may be as many as three Canadian stocks on the east coast--Newfoundland/Labrador, Nova Scotia, and Gulf of St. Lawrence (Mitchell 1974)--the stock structure in the North Atlantic is not well resolved (Waring et al. 2002).

Recent genetic analyses distinguished between eastern and western populations of North Atlantic fin whales, but did not identify any significant genetic differences between individuals from the Gulf of St. Lawrence and the Gulf of Maine (Bérubé et al. 1998). Coakes et al. (in prep.) photo-identified 36 animals near Halifax in 1997, of which 9 had been photographed previously in the Gulf of Maine and three in the Gulf of St. Lawrence. Considerable exchange has been documented throughout the Gulf of St. Lawrence and with Nova Scotia and the Gulf of Maine by researchers operating from Mingan Island, on the north shore of the Gulf of St. Lawrence (Richard Sears, personal communication. Mingan Island Cetacean Study, 285 rue Green, St. Lambert, Québec, Canada, J4P 1T3). These observations imply that at least the putative Nova Scotia and Gulf of St. Lawrence stocks may be from the same population.

The IWC considers the fin whales in the eastern North Pacific a single stock, while NMFS recognizes three stocks in the eastern North Pacific: Northeast Pacific, Hawaii, and California-Oregon-Washington (Carretta et al. 2002). Fujino (1960)concluded that the North Pacific contains an eastern and a western population based on histological and marking data. The marking data further suggested that the fin whales off British Columbia may be isolated to some degree.

There is some evidence of more than one stock in the eastern North Pacific, or at least for several feeding grounds. Year-round concentrations of fin whales in the Gulf of California (Tershy et al. 1990) involve a genetically isolated population (Bérubé et al. 2002). Year-round occurrences are also observed in the south/central California region (Forney et al. 1995). Summer aggregations have been documented in Oregon; and summer-fall groups have been observed in the Shelikof Strait/Gulf of Alaska region (Carretta et al. 2002). Recovered tags from the eastern North Pacific suggested that fin whales summer between Alaska and central California (Rice 1974).

The Northeast Pacific and the Nova Scotian stocks, and possibly the California-Oregon-Washington stock, are trans-boundary stocks, frequenting habitat in both Canadian and U.S. territorial waters (Figure 2). The core summer range of the putative Gulf of St. Lawrence and Newfoundland/Labrador stocks would be solely in Canadian waters.

Canadian range

Fin whales are seen and reported much more regularly in Atlantic than in Pacific waters of Canada. This is at least partially attributable to greater observational effort within the species range in Atlantic Canada.

Fin whales are common along the east coast of North America in the summer months and are also often seen in winter, particularly along the Atlantic coast of Nova Scotia (Brodie 1975, Gaskin 1982). Summer aggregations have been noted off Newfoundland, in the St. Lawrence, on the Atlantic coast of Nova Scotia, and in the Bay of Fundy (Mitchell 1974, Perkins and Whitehead 1977, Sergeant 1977).

The fin whale has been described as the most abundant large whale in the Bay of Fundy from June through fall (Gaskin 1983). The North Atlantic Right Whale Consortium (NARWC) database contains extensive sightings in this region (Kate Bredin, personal communication. Atlantic Canada Conservation Data Centre, Mount Allison University, P.O. Box 6416, Sackville, NB, E4L 1G6). The Species at Risk (SAR) database maintained by DFO (Sean C. Smith, personal communication. Department of Fisheries and Oceans, St. Andrews Biological Station, 531 Brandy Cove Rd., St. Andrews, NB, E5B 2L9) contains concentrations of sightings there and along the edge of the Scotian shelf (Figure 3). The majority of the sightings are from whale watching enterprises in the Bay of Fundy and the marine observer program. Sightings off Labrador and Newfoundland (Figure 4), maintained by DFO’s Newfoundland & Labrador Region (Jack Lawson, personal communication. Marine Mammal Section, Newfoundland & Labrador Region, Fisheries and Oceans Canada, P.O. Box 5667, St. John's, NL, A1C 5X1) demonstrate the continued occurrence of fin whales in this area. These data include sightings from aerial surveys conducted in 2002 and 2003, from which estimates of fin whale density and abundance are expected some time in 2005 (J. Lawson, personal communication). A map of sightings from the St. Lawrence was not available.

During aerial surveys between Cape Hatteras, North Carolina and Nova Scotia (1978–1982), fin whales made up 46% of all large whale sightings and 24% of all cetacean sightings (CeTAP 1982). These surveys indicated a wide distribution across the continental shelf, extending well offshore into waters deeper than 2,000 m, showing that few areas between Cape Hatteras and Nova Scotia were not occupied by fin whales at some time during the year (Hain et al. 1992).

Fin whales were also sighted on the Scotian Shelf more frequently and in greater overall numbers than any other species on the whaling grounds in the late 60s early 70s (Mitchell et al. 1986). Studies conducted on the shelf at various locations from Nova Scotia to Labrador have regularly encountered fin whales (Perkins and Whitehead 1977, Whitehead and Glass 1985, Whitehead et al. 1998).

Some animals summer near Tadoussac, Quebec in the St. Lawrence Estuary (Sergeant 1977), where 88 individuals have been photo-identified between 1986–2001(Giard et al. 2001). About 30% are considered seasonal residents, while the remainder are considered regular or occasional visitors. Since 1998, the photo-id “discovery curve” has levelled off at 2–4 new sightings per year, suggesting a seasonally resident population of approximately 26 animals (Giard et al. 2001). On the north shore of the Gulf of St. Lawrence, over 300 different fin whales have been photo-identified since the early 1980s (R. Sears, personal communication).

In British Columbian waters, fin whales were frequently observed in exposed coastal seas (Hecate Strait and Queen Charlotte Sound) and occasionally in the more protected waters of Queen Charlotte Strait and the Strait of Georgia (Pike and MacAskie 1969). Only about 17% of the catch by British Columbia coastal stations for which positions were recorded was on the continental shelf (Gregr 2004).

Based on a comparison of whaling records from coastal stations around the Gulf of Alaska, Gregr et al. (2000) concluded that the species did not appear restricted latitudinally. An analysis of whaling records from British Columbia whaling stations (Figure 5) identified fin whale habitat along the continental shelf, in the exposed inland waters of Dixon Entrance and Hecate Strait, and in a region offshore of northern Vancouver Island (Gregr and Trites 2001).

Contemporary sightings of fin whales in British Columbia waters are predominantly from the west coast of Vancouver Island, and the inland waters of Hecate Strait and Queen Charlotte Sound. Recent annual spring and summer cruises (2001–2003) have regularly recorded fin whales in off-shelf waters, near the shelf edge boundary of Queen Charlotte Sound, in Hecate Strait, and in Dixon Entrance (John K.B. Ford, personal communication. Fisheries and Oceans Canada, Pacific Biological Station, Nanaimo, BC, V9R 5K6). Sightings are also reported off the southern end of Vancouver Island in summer (Brian Gisborne, personal communication. Juan de Fuca Express, 427-118 Menzies Street, Victoria, BC, V8V 2G5). Additional surveys conducted in August 2002 and 2003 found fin whales in Queen Charlotte Sound and Hecate Strait (J. Calambokidis, personal communication. Cascadia Research Collective, 218 1/2 W. 4th Avenue, Olympia, WA 98501 USA).

The B.C. Cetacean Sightings Network (BCCSN) contains 83 fin whale sightings from 1985 to 2003; with the majority between 1999 and 2003, and virtually all provided by recreational boaters (Doug Sandilands, personal communication. Vancouver Marine Science Centre, P.O. Box 3232, Vancouver, BC, V6B 3X8). The sightings are concentrated around the Queen Charlotte Islands and in Hecate Strait, with some off the west coast of Vancouver Island (Figure 6). There are no recorded winter sightings, nor are there any contemporary sightings in the Strait of Georgia (J.K.B. Ford, personal communication). The last review of the status of marine mammals in the Strait of Georgia (Calambokidis and Baird 1994) made no mention of fin whales.

NMFS conducted 2-week summer surveys in the northern offshore waters of Washington State each year from 1995 to 2002 and did not sight a single fin whale (Calambokidis et al. 2004). Similarly, aerial surveys off the west coast of Washington and southwest coast of Vancouver Island in the early 1990s also did not spot any fin whales (Green et al. 1992 cited in Calambokidis et al. 2004).

A recent (2004) line-transect survey of British Columbia’s inshore waters did not produce enough sightings to generate a population estimate. However, observations in Queen Charlotte Sound and Dixon Entrance served to confirm the limited inshore distribution of the species in the Canadian Pacific (Rob Williams, personal communication, Raincoast Conservation Society, Pearse Island, P.O. Box 193 Alert Bay, BC, V0N 1A0).