Whales, Dolphins, and Porpoises of the Western North Atlantic Part 14

Distribution

Though bowhead whales in the western North Atlantic were once distributed from Arctic waters, from the edge of the ice, south as far as the Strait of Belle Isle and the St. Lawrence River in such abundance that they were once referred to simply as "the whale," overwhaling through the 19th century until as recently as 1911 has severely reduced their numbers and restricted their modern range. Today in addition to the more abundant populations of the Bering, Beaufort, and Chukchi seas and the Sea of Okhotsk, there are populations off eastern Greenland and in Davis Straits, Baffin Bay, James Bay, and the adjacent waters. Within these ranges, bowhead whales move southward in front of the advancing ice floes and may be expected near the southern limits of their range from September or October through the early spring months. Populations in the western North Atlantic appear to be increasing slowly.

Stranded Specimens

In addition to the fact that their ranges may overlap only slightly if at all, bowhead whales may be distinguished from the other right whales of the western North Atlantic by differences in 1) primary distribution, 2) coloration, 3) lengths of the longest baleen plates, and 4) presence of callosities.

BOWHEAD WHALE RIGHT WHALE

DISTRIBUTION

Arctic distribution south to Texas, southwest Florida Davis Straits only during north to Iceland, reaching winter. northern limits only during spring and summer.

COLORATION

Black with white "vest" on Sometimes black often front part of lower jaw, brown or mottled with regions sometimes containing a of white on chin and string of black spots; upper belly; patches of yellowish to jaw lacks the "rock garden." pink callosities and lice encrusting the snout in what has been called a "rock garden."

BALEEN PLATES

325-360 per side; plates to 14 250-390 per side 12 inches (35.6 cm) at base and inches (30.5 cm) at base and longest plates up to 14 feet up to 7.2 feet (2.2 m) long.

(4.3 m) long. Dark gray or Dirty gray with black fringes; black with gray fringes; some anterior plates anterior margin of some partly or completely white.

plates whitish, showing green iridescence in sunlight.

BONNET AND OTHER CALLOSITIES

Not present. Present.

[Ill.u.s.tration: Figure 43.--Swimming adult bowhead whales, particularly males, often show two characteristic humps or curves to the back--one on the head, ending just behind the blowholes, and a larger curve from just behind the blowholes to near the flukes; the second is accentuated when the animal humps up to begin a dive. (_Photo by J. Lentfer._)]

[Ill.u.s.tration: Figure 44.--Bowhead whales have no dorsal fin. The back is smooth and black, though often irregularly s.p.a.ced white or grayish scars of unknown origin appear. (_Photos by J. Lentfer._)]

[Ill.u.s.tration: Figure 45.--The unusually shaped head and the broad lower jaw, colored by a broad white vest, are evident in the swimming bowhead whale (left) and in both members of the copulating pair (right). Also evident on the animal to the far left is the "string of black beads"

which is sometimes found in the white region. (_Photos by J. Lentfer._)]

[Ill.u.s.tration: Figure 46.--A harpooned bowhead whale (this one from the Alaskan population). Note the high arching upper jaw of the species.

Bowhead whales have up to at least 360 plates per side, far more than the black right whale. The longest plates, located near the middle of each jaw, are reported to reach 12 feet (3.7 m), or more, in length.

(_Photo by D. R. Patten._)]

RIGHT WHALE (B)

_Eubalaena glacialis_ (Borowski 1781)

Other Common Names

Black right whale, Biscayan right whale, Biscay whale, Nordcaper right whale.

Description

These right whales reach a length of about 53 feet (16.2 m).

The body is rotund and completely lacking a dorsal fin or a dorsal ridge. The upper jaw is long, narrow, and highly arched. The lips are similarly highly arched. The top of the head has a series of b.u.mps or callosities, the largest one of which is known as the "bonnet," on the upper surface in front of the blowholes. Yellowish-brown lice and, less frequently, barnacles grow on the callosities. The color and extent of the callosities varies from one individual to the next.

The two blowholes are widely separated, resulting in the projection of the blow upward as two distinct spouts. The body is dark on the back, sometimes black, more often brown or mottled, usually has a region of white on the chin and belly, and sometimes has numerous small grayish-white scars of unknown origin. The baleen plates are up to 7.2 feet (2.2 m) long, very narrow, and variable in color from dark brownish through dark gray to black in color. When the animals swim, mouth agape near the surface, the baleen sometimes appears pale yellowish gray in color.

Natural History Notes

Right whales are usually not wary of boats and may often be approached very closely.

Like sperm and humpback whales, they usually throw their flukes high into the air when beginning a long dive.

Right whales feed primarily on copepods.

Historically, this whale was nearly exterminated by hunters, who took advantage of its slow speed and who knew that its carca.s.s floats, to harvest these animals for their great yield of whalebone and oil. It was these characteristics which prompted whalers to dub these animals the "right" whales to kill (as opposed to the ones that were too fast to catch and sank when killed).

May Be Confused With

The distinct blow of the right whales and their smooth dark back, devoid of any traces of a dorsal fin, make it unlikely that the species will be confused with any other large whales except, perhaps, the bowhead whale.

In the event that the expansion of their ranges again causes these two species to overlap in distribution, they can be distinguished from one another by the characteristics discussed on p. 49.

If only the flukes are seen as the animal begins a dive, right and bowhead whales may be distinguished from the other two species of large whales exhibiting this behavior, the sperm and the humpback, in this way: the flukes of right and bowhead whales are broad, pointed on the tips, greatly concave towards a deep fluke notch, and dark below: those of the sperm whale are more nearly triangular, while those of the humpback whale have a jagged irregular or rippled rear margin and are sometimes variously white below.

Distribution

Like its more northern relative, the bowhead whale, the right whale was once the object of a widespread and extensive whale fishery, which reduced the species to critically low numbers.

Though the former range of right whales is not clearly known, the species is thought to have been abundant from the Davis Straits south at least to the Carolinas and Bermuda and to have occurred in winter to Florida and perhaps into the Gulf of Mexico.

Currently, right whales are known from Iceland south to Florida. Animals move north along the eastern Florida coast between early January and late March. During this time the species has also been observed in the Gulf of Mexico off southwestern Florida and Texas. Right whales pa.s.s the coast of New England in fair numbers in spring and continue as far north as at least Nova Scotia. Right whales are also found off Iceland, though the migration routes to and from Iceland waters are not known. The recent apparent increases in numbers at the northern and southern coastal approaches in New England and Florida, respectively, lend credibility to the hopeful contention that the species will again recolonize its historical range.

Stranded Specimens

Stranded right whales can be easily identified by all the characters discussed on p. 49 and summarized in Table 2.

[Ill.u.s.tration: Figure 47.--The V-shaped blow characteristic of right whales. Note the two distinct spouts, bushy in appearance. (_Photo off Cape Cod by W. A. Watkins._)]

[Ill.u.s.tration: Figure 48.--A right whale off the northeastern Florida coast. Note the robust body, the smooth back, completely lacking a dorsal fin, and the narrow rostrum, bearing the characteristic yellowish callosities. Right whales, primarily mothers with calves, show up on the Florida coast in the early spring on their slow annual migration to the north. (_Photo by N. Fain, courtesy of Marineland of Florida._)]