Whales, Dolphins, and Porpoises of the Western North Atlantic Part 24

Grampus feed on fish and squid.

May Be Confused With

From a distance grampus are most easily confused with Atlantic bottlenosed dolphins. They may be most readily distinguished by the following differences:

ATLANTIC BOTTLENOSED GRAMPUS DOLPHIN

SIZE

To 13 feet (4 m). Rarely to 12 feet (3.7 m); usually less than 10 feet (3.1 m).

BODY COLOR

Young are uniform light Dark gray on body; lighter gray; older animals dark gray on sides; white or pink with grayish regions on on belly; may appear brownish chest and belly; very in water.

old animals white and scarred.

DORSAL FIN

To 15 inches (38.1 cm); To 12 inches (30.5 cm) less sharply falcate; pointed sharply falcate; pointed on on tip. tip.

HEAD COLOR AND SHAPE

Blunted and creased on Uniformly brownish to gray front; frequently all distinctly bottlenosed.

white in larger animals.

MARKINGS

Very often extensively Less frequently scratched scarred. and scarred.

Distribution

Grampus are known to be distributed in temperate and tropical seas from at least eastern Newfoundland, south at least to St. Vincent, Lesser Antilles, and in the eastern and northern Gulf of Mexico. The species may not be as rare as the paucity of records suggests. Though they have been seen in Buzzards Bay on several occasions, grampus generally have an oceanic range and, along the Atlantic coast of North America, may be distributed from the Gulf Stream seaward, outside the theater of normal boating traffic.

Stranded Specimens

Stranded grampus are most readily identifiable by 1) the presence of only seven, or fewer, teeth in each side of the lower jaw (many of those teeth may have dropped out in older animals and remaining teeth may be extensively worn) and the absence of teeth in the upper jaw; 2) the presence of a distinct crease or bifurcation in the melon on the extreme front of the head; 3) the presence of numerous scratches and scars all over the body; and 4) the tall, slender, sharply falcate dorsal fin which may be more than 15 inches (38.1 cm) tall.

[Ill.u.s.tration: Figure 103.--Grampus are frequently found in small tight groups "porpoising." From a distance they may resemble the Atlantic bottlenosed dolphins, though grampus have taller dorsal fins, blunted beakless heads, and lighter coloration. (_Photo off Was.h.i.+ngton State by C. Fiscus._)]

[Ill.u.s.tration: Figure 104.--Grampus off Fistler, Scotland (top) and from Baja California in the tank of Sea World, Inc., San Diego, Calif.

(bottom). Note the tall pointed dorsal fin, which remains dark even in adult animals, the blunted head, which lacks a beak, and the extensive scarring of the body. In the photo on the right, note also the long pointed flippers and the white head characteristic of older animals.

(_Photos by A. S. Clark (top) and courtesy of D. K. Caldwell (bottom)._)]

[Ill.u.s.tration: Figure 105.--Grampus, particularly younger animals, have two regions of grayish-white on the ventral surface, one in front of the flippers and another beginning on the belly narrowing towards the tail.

These markings closely resemble the ventral marking of pilot whales.

(_Photos courtesy of Marineland of Florida._)]

[Ill.u.s.tration: Figure 106.--Stranded grampus can be readily identified.

On this captive animal note the blunted head, the distinct crease on the front of the head (see also Fig. 107), and the extensive scarring of the body. (_Photo courtesy of D. K. Caldwell._)]

[Ill.u.s.tration: Figure 107.--Grampus have seven or fewer teeth in each side of the lower jaw. (None in the upper jaw.) Many of these teeth may have fallen out of older specimens, and the remaining teeth may be extensively worn. (_Photo courtesy of Marineland of Florida._)]

Medium-sized Whales Without a Dorsal Fin

BELUGA (T)

_Delphinapterus leucas_ (Pallas 1776)

Other Common Names

White porpoise, white whale, belukha, sea canary, marsouin blanc (Quebec).

Description

Belugas reach a maximum overall length of about 16 feet (4.9 m). Males are slightly larger than females. In the western North Atlantic they have been found to grow to greatest lengths in oceanic environments near the southern extremities of their ranges, though they are found in far greater abundance in estuarine areas of the Arctic. Belugas have extremely robust bodies tapering to a distinct "neck" region and a very small head relative to body size.

They do not have a dorsal fin. Instead, along the back just behind the midpoint there is a narrow ridge notched laterally to form a series of small b.u.mps. These ridges may be clearly visible on a swimming animal.

Newborn belugas are brown. As they age, they gradually lighten through slate gray, and by their sixth or seventh year have a.s.sumed the all-white coloration characteristic of adult animals.

Natural History Notes

Belugas feed on a variety of fishes (including cod and capelin), on squid, and on a variety of benthic crustaceans.

They are frequently found in shallow bays and river mouths, where the young are born, and occasionally ascend rivers.

May Be Confused With

Because of their limited distribution, all-white coloration and lack of a dorsal fin, belugas are unlikely to be confused with any other species of cetacean.

Distribution

Belugas have been reported from the Arctic Circle south as far as eastern Connecticut, typically in estuarine habitats, though they do range into oceanic regions. They are most abundant from the north sh.o.r.e of the Gulf of St. Lawrence northward. They remain near the Arctic Circle and in Hudson Bay to northern Greenland during winter, undertaking migrations to the south in autumn, straggling to the Maritime Provinces and as far as Connecticut. Belugas are regularly seen in the St. Lawrence and Saguenay rivers throughout late spring and summer. Return migrations to the north take place in spring.

A small population in the estuary of St. Lawrence is resident throughout the year.