The North Atlantic Marine Mammal Commission

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NAMMCO 25

Distribution and Habitat

The fin whale has a worldwide distribution, occurring in the Atlantic, Pacific, Indian and Arctic Oceans. In all oceans, it ranges from tropical to polar regions, primarily in temperate to polar latitudes, being rare in tropical or ice-covered polar seas. Fin whales are largely pelagic (open-ocean dwellers), but may be seen in coastal waters in some areas, sometimes occurring in waters as shallow as 30 m.

At least 3 distinct worldwide populations are recognized - Southern Hemisphere, North Atlantic and North Pacific - which are further subdivided genetically (e.g., Martin 1990). Some taxonomists classify fin whales from the Northern and Southern Hemispheres as two subspecies, B.p. physalus and B.p. quoyi respectively. Northern and Southern Hemisphere populations never meet or mix across the equator because the seasonal patterns are reversed in the two hemispheres, and so they migrate to the equator at different times of year.

In the central and western Mediterranean, there is a resident subpopulation, which is genetically distinct from that of the North Atlantic (Bérubé et al. 1998).

Distribution in the North Atlantic

The 20-year long series of NASS and T-NASS summer sightings surveys provides a good understanding of the potential summer distribution of the species in the North Atlantic. The surveys are centred upon the three first week of July.

fin whales all 5 NASS survey s

Fin summer dist all NASS coda SnessaSummer distribution of common minke whales in the North Atlantic, showing sightings and effort from all North Atlantic Sightings surveys, 1987 – 2007, as well as 2007 CODA and SNESSA surveys.

The species is present in summer over the entire NAMMCO area, ranging from temperate to polar waters, when it is most common off Nova Scotia and Newfoundland, in the Davis Strait off Western Greenland, in the East Greenland – Iceland – Jan Mayen area and west of the Iberian Peninsula.

Migration

Fin whales are migratory, and exhibit seasonal north-south movements between lower latitudes in winter to warmer breeding grounds and high latitudes in summer to cold feeding grounds (Kellogh 1929, Mackintosh 1965, 1966). These migrations do not, however, necessarily involve the entire population and several resident populations are known to exist, as in the Mediterranean (Lockyer 1984, Mizroch et al. 2009).

North Atlantic fin whales may occur to some extent throughout the year in all of their range, as suggested by acoustic data (Clark 1995), although the density of individuals in any one area may change seasonally.

Fin whales are not usually seen in groups near islands or coasts and are difficult to study in the wild. Studying their habitat use is challenging for many reasons, including the large temporal and spatial scale needed. This is especially true in high latitudes, because of harsh environmental conditions. Knowledge has long been limited. Clear migratory routes and wintering (breeding) grounds have not been identified.

New techniques have recently permitted monitoring of the acoustic activity of cetaceans, witness to their presence and activities, over long-time periods, and independently of weather, sea, ice and light conditions (Mellinger et al. 2007). Simon et al. (2010) have recently brought new information on the migratory pattern and habitat use of fin whales in the Davis Strait, between Greenland and Canada, by monitoring the whales' acoustics activity using three bottom-moored acoustic recorders over a 2-year period. They showed that fin whales are present in the area from June to at least the end of December and thus that at least part of the population migrate south much later than October, as previously believed (e.g. Norris 1967, Heide-Jørgensen et al. 2008). Also, not all the whales migrate south to mate, some continue feeding, starting mating at high latitudes.