with none of the mottling present on blue whales and are rarely as
heavily scarred as sei whales. Along the back, just behind the head,
there is a grayish-white chevron, with the apex along the midline of the
back and the arms of the chevron oriented posteriorly, which is
sometimes distinctive and may be visible as the animals surface to
breathe. The undersides, including the undersides of the flukes and
flippers, are white. On the head, the dark coloration is markedly
asymmetrical, reaching farther down on the left than on the right side.
The right lower lip, including the mouth cavity, and the right front
baleen (approximately one-fifth to one-third) are yellowish white.
Occasionally the right upper lip is also white. The remainder of the
plates on the right side and all those on the left side are striped with
alternate bands of yellowish white and bluish gray. The fringes of the
plates are brownish gray to grayish white.
Natural History Notes
Fin whales are one of the most common baleen whale species in the world
and constitute a major portion of the whaling catch. They are reportedly
one of the fastest of the big whales (sei whales may be slightly faster)
possibly reaching burst speeds in excess of 20 knots, and were not an
important commercial species until the comparatively recent development
of fast catcher boats and the depletion of blue whale stocks.
A fin whale's blow can be from 15 to 20 feet (4.6 to 6.1 m) tall and has
been described as an inverted cone or an elongated ellipse.
Fin whales dive to at least 755 feet (230.1 m). This depth is probably
deeper than that of either blue or sei whales, a factor usually
reflected in differences among the surfacing, blowing, and diving
characteristics of these three species. When they are moving leisurely
at the surface, fin whales expose the dorsal fin shortly after the
appearance of the blowholes, slightly later than that of the sei whales.
When they are surfacing from a deeper dive, however, they surface at a
steeper angle, blow, submerge the blowholes, and then arch the back and
dorsal fin high into the air before beginning another long dive. In this
species it can be generally stated that the maximum amount of the back
in the area of the dorsal fin which is exposed above the surface as the
animal sounds is approximately 2 times the height of the dorsal fin. Fin
whales do not show their tail flukes when beginning a dive.
Unlike blue or sei whales, fin whales do breach on occasion. When they
do leap clear of the water, fin whales usually reenter with a resounding
splash, like that made by humpback and right whales and not smoothly,
head first, as minke whales often do.
Fin whales are sometimes found singly or in pairs but more often occur
in pods of six or seven individuals and many pods consisting of as many
as 50 animals may be concentrated in a small area.
Fin whales calve and breed in winter, mostly in temperate waters.
Atlantic fin whales eat a wide variety of foods, including krill,
capelin, squid, herring, and lanternfish.
May Be Confused With
Fin whales may be confused with blue whales, sei whales, and, in the
southernmost portion of their range, with Bryde's whales. They may be
distinguished from the blue whales by differences in overall coloration,
coloration and shape of the head, and the size, position, and time of
appearance of the dorsal fin at the surface (see p. 19). After close
examination they may be distinguished from Bryde's whales by the
presence of three ridges along the head (of the Bryde's whale) and by
the smaller, more sharply pointed falcate dorsal fin of the Bryde's
whale (see Fig. 31). They may be distinguished from sei whales in the
following similar ways:
FIN WHALE SEI WHALE
DORSAL FIN
Slightly falcate, forms angle Sharply pointed and falcate:
of less than 40 deg. with back forms angle of greater than
slightly more than one-third 40 deg. with back well more than
forward from tail. one-third forward from tail.
SURFACING BEHAVIOR
Usually rise obliquely so top Primarily skimmer feeders;
of head breaks surface first; usually rise to surface at
after blowing, animal arches shallow angle so that dorsal
its back and rolls forward fin and head are visible
exposing the dorsal fin on the almost simultaneously; when
long dive; on sounding, the starting the long dive does
maximum amount of back in not usually arch the back as
the area of the dorsal fin much as the fin whale; on
which is exposed is approximately sounding, the maximum
2 times the height of amount of back in the area of
dorsal fin. the dorsal fin which is
exposed is approximately 1
times the height of the dorsal
fin.
BLOW
Tall (to 20 feet [6.1 m]); Similar shape but smaller--rarely
inverted cone (point down) taller than 10-15 feet
or elongated ellipse. (3.1-4.6 m).
DIVING
Dive for 5-15 (usually 6-7) Dive for 3-10 min; usually
min; blow 3-7 times or more blow at even intervals over
at intervals of up to several long periods of time; often
minutes, then dive again. visible just below the surface,
even on longer dives.
COLOR OF UNDERSIDES
White higher up on right Mostly gray; irregular whitish
than on left side. area on belly.
COLOR OF LOWER LIP
White on right, gray on left. Gray.
BALEEN PLATES
Right one-fifth to one-third Ash black with a blue tinge
in front white; all others and fine grayish bristles.
alternate bands of yellowish
white and bluish gray; bristles
grayish white.
Distribution
Fin whales are probably the most numerous and widely distributed large
whale species in the western North Atlantic.
Fin whales summer from below the latitude of Cape Cod, Mass., north to
the Arctic Circle. (They are frequently seen between New York and
Bermuda this time of year.) Within this zone they may sometimes be seen
very close to shore and appear to be concentrated between shore and the
1,000-fathom curve from at least lat. 41 deg.20' to 57 deg.00' N. In recent
years they have been reported in relatively large numbers in the Gulf of
Maine from March through June, off Newfoundland as early as June but
increasing to August, and entering Davis Straits and beyond in
substantial numbers in midsummer to late summer. There is some evidence
that the animals venturing farthest north are the largest individuals of
the species. Movements of the population(s) southward have usually begun
by October, though some fin whales sometimes remain in the northern seas
sufficiently long to become trapped in the ice and killed.
During winter the range of fin whales spreads out from the advancing ice
southward, reaching at least to the coast of Florida, into the Gulf of
Mexico, and to the Greater Antilles, though fin whales are not at all
common in tropical waters. During the winter many fin whales move into
offshore waters. Northward migrations probably begin in midspring.
Fin whales may be found in Cape Cod waters all year long.
There may be two or possibly three separate stocks of fin whales in the
western North Atlantic, one more northern cold-adapted stock and another
more southern stock. The ranges of the two stocks appear to overlap,
such that the winter range of the northern stock probably becomes the
spring and summer range of the more southern stock. The third stock may
consist of an isolated population in the northern Gulf of Mexico.
Stranded Specimens
Stranded fin whales may be most readily identified by 1) the
yellowish-white coloration of the right front baleen and the right white
lower lip; 2) the numerous baleen plates (262-473 in number); 3) the
numerous ventral grooves (56-100 in number) extending to the navel and
beyond (Table 2); and 4) the broad, flat sharply pointed head with only
a single head ridge.
[Illustration: Figure 15.--The heads of fin whales surfacing to breathe
off Japan and in the northern North Atlantic (inset). When they can be
approached from the right side, fin whales can be positively
distinguished from the other large balaenopterine species by the white
coloration of the right lower lip and the flat, narrow head. Note also
the single central head ridge. (_Photos by Japanese Whales Research
Institute, courtesy of H. Omura, and K. C. Balcomb_ (_inset_).)]
[Illustration: Figure 16.--A small group of fin whales off British
Columbia. Fin whales may be found in groups of up to six or seven
individuals and these groups may congregate in feeding grounds. (_Photo
by G. C. Pike, courtesy of I. MacAskie._)]
[Illustration: Figure 17.--The back of a harpooned fin whale in the
eastern North Pacific (left) and in the North Atlantic (right). In both
note the light grayish-white chevrons just behind the head. These
chevrons are not usually very distinctive in North Atlantic fin whales.
In the animal in the left photo note also the prominent ridge along the
back behind the dorsal fin--a characteristic which prompted the common
name "razorback." (_Photos courtesy of_ Los Angeles Examiner (_left_)
_and K. C. Balcomb_ (_right_).)]
[Illustration: Figure 18.--Surfacing fin whales show the head and blow,
then the wheellike silhouette of the back, and then the dorsal fin. Note
that in this species the dorsal fin is smaller and located farther back
than that of the sei whale and appears on the surface later after the
animal's blow. (_Photo from the northern North Atlantic by K. C.
Balcomb._)]
[Illustration: Figure 19.--As they begin a long dive, fin whales
frequently arch the tail stock high into the air, exposing the dorsal
fin. Even on a long dive, however, this species is not known to throw
its tail flukes high into the air or even to raise them slightly, as
blue whales sometimes do when beginning a long dive. (_Photo from off
Virginia by J. G. Mead._)]
[Illustration: Figure 20.--Probably a fin whale (perhaps a Bryde's
whale) breaching in the eastern tropical Pacific. This type of behavior
has been described for humpback, minke, and fin whales but is far more
common for the first two species. Breaching fin whales often reenter the
water with a resounding splash, much like humpback whales, but sometimes
smoothly, head first, as minkes sometimes do. (_Photo by K. D. Sexton,
courtesy of National Marine Fisheries Service._)]
[Illustration: Figure 21.--A head-on view of a fin whale stranded at
Ormond Beach, Fla. Note the flat narrow appearance of the head and the
single, central head ridge. (_Photo by F. Essapian, courtesy of
Marineland of Florida._)]
[Illustration: Figure 22.--In this partly flensed fin whale, at
Blanford, Nova Scotia, note the white lower lip and the white baleen in
the right front. The inset photo shows the right upper jaw of a fin
whale with the baleen intact. (_Photos by H. E. Winn, and from the North
Pacific by Japanese Whales Research Institute, courtesy of H. Omura
(inset)._)]
[Illustration: Figure 23.--A fin whale on the ramp of the whaling
station also at Blanford, Nova Scotia. Note the ventral grooves, 56 to
100 and extending at least to the navel. (_Photo by L. Rigley._)]
SEI WHALE (B)
_Balaenoptera borealis_ Lesson 1828
Other Common Names
Pollack whale, sardine whale, Rudolphi's rorqual.
Description
Sei (pronounced "say") whales have been reported to reach 62 feet (19
m).
The snout is less acutely pointed than that of the fin whale but when
viewed from the side appears slightly arched. In general, the head is
intermediate in shape between that of the blue whale and that of the fin
whale. The dorsal fin, which is from 10 to 24 inches (25.4 to 61 cm)
tall and strongly falcate in adult animals, is located about two-thirds
of the way back on the back, farther forward than that of the blue or
fin whales. Sei whales are dark steel gray on the back and sides, and on
the posterior portion of the ventral surface. The body often has a
galvanized appearance due to scars possibly resulting from lamprey bites
inflicted during migrations into warmer waters. These scars may be dark
gray to almost white in color. On the belly there is a region of grayish
white that is confined to the area of the ventral grooves. Neither the
flippers nor the tail flukes are white underneath. The right lower lip
and the mouth cavity, unlike those of the fin whale, are uniformly gray.
The baleen plates are uniformly grayish black with fine grayish-white
fringes. (A small number of sei whales have been noted to have a few
half-white plates near the front of the mouth, a feature which might
result in their confusion with fin whales.)
Natural History Notes
The blow of sei whales is an inverted cone rarely taller than 15 feet
(4.6 m).
Sei whales are generally skimmer feeders and do not usually dive very
deeply. For that reason they usually surface at a shallower angle than
fin whales. The head rarely emerges at a steep angle (except when the
whales are chased). Instead, the blowholes and a major portion of the
back, including the dorsal fin, become visible almost simultaneously and
remain visible for relatively long periods of time. In this species it
can be generally stated that the amount of the back in the area of the
dorsal fin which is exposed above the surface as the animal sounds is
approximately the same height as the dorsal fin. When they begin another
dive, sei whales do not arch the tail stock or flukes high. Instead,
they normally submerge by slipping quietly below the surface, often
remaining in view only a few feet down and leaving a series of tracks or
swirls on the surface as they move their tail flukes. When they are
feeding in this manner, sei whales may exhibit a highly regular blowing
and diving pattern over long periods of time.
Sei whales usually travel in groups of from two to five individuals,
though they may concentrate in large numbers on the feeding grounds.
In the northern portion of their range, sei whales feed on copepods.
Throughout the remainder of the range, however, their food is more
varied and also includes krill and a variety of small schooling fishes.
The species derived its common name, in fact, from its frequent
occurrence with or near sei fish.
May Be Confused With
The sei whale's smaller size and decidedly taller, more falcate dorsal
fin located well more than one-third forward from the tail should
prevent confusion with the blue whale. At a distance, however, sei
whales are difficult to distinguish from either fin whales or Bryde's
whales. The primary clues for distinguishing them from fins are the
differences in swimming, blowing, and diving characteristics tabularized
in detail on p. 26 and the asymmetrical coloration of the fin whale.
Sei whales may be distinguished from Bryde's whales only upon close
examination. The dorsal fin of Bryde's whales is small, to 18 inches
(45.7 cm), sharply pointed, and often worn on the rear margin. If close
examination is possible, the sei whale will be seen to have only a
single head ridge. Bryde's whales have two additional ridges--one on
each side of the main ridge. Bryde's whales are primarily fish feeders
and their diving behavior more closely resembles that of a fin whale
than that of a sei whale. (See p. 37).
Distribution
The distribution and migrations of the sei whale during most of the year
are rather poorly known. The species is known to avoid the colder
regions near the pack ice and to range from Iceland south to the
northeast Venezuelan coast and the northeast and southwest Gulf of
Mexico. There are also records from Cuba and the Virgin Islands. Along
the northeast United States and eastern Canadian coasts, where most
research on sei whales has been conducted, the species migrates from New
England through the Blanford, Nova Scotia area in June and July, is
found in small numbers off eastern Newfoundland in August and September
(abundant in Placentia Bay, Newfoundland in August), and continues
northward to the Davis Straits in September and October. An offshore
stock may be found year-round in the Labrador Sea. The summer range (May
to September or October) extends from New England to southern Arctic
waters. Though some individuals remain behind through November, the
southward movement of the bulk of the population presumably begins in
October. In general, sei whales do not venture as far north as fin
whales but may have a greater tendency to enter tropical waters.
Stranded Specimens
Stranded sei whales are most likely to be confused with fin whales or
Bryde's whales. The three head ridges of the Bryde's whale (sei whales
have only one) assist in distinguishing sei whales from Bryde's whales.
They may be distinguished from fin whales and all other rorquals by the
following characteristics: 1) The color of the baleen plates--uniformly
ash black with a blue tinge and fine white bristles (Table 2). 2) The
density of bristles on the plates--sei whales have from 35 to 60 baleen
fringes per centimeter; all other rorquals have far fewer (less than
35). 3) The relative lengths of the ventral grooves--the grooves of sei
whales end well before the navel; those of blue, fin, and Bryde's whales
extend at least to the navel. 4) The relatively small numbers of ventral
grooves (38-56)--both blue and fin whales have more; Bryde's whales have
approximately the same number.
If the animal is not in an advanced state of decomposition, the region
of white coloration of the belly may also be visible.
[Illustration: Figure 24.--The head of a sei whale is intermediate in
shape between that of the blue whale and that of the fin whale. When
viewed from the side it is slightly arched. Note the single central head
ridge, from just in front of the blowholes to near the tip of the snout.
Bryde's whales, with which sei whales are most likely to be confused in
the tropical and subtropical portions of their range, have two auxiliary
ridges, one on each side of the top of the head, in addition to this
main central ridge. (_Photo from the North Pacific by Japanese Whales
Research Institute, courtesy of H. Omura._)]
[Illustration: Figure 25.--Sei whales are dark gray on the right lower
lip. They can be distinguished from fin whales, which have a white right
lower lip, by approaching them from the right side. (_Photo from the
North Pacific by Japanese Whales Research Institute, courtesy of H.
Omura._)]
[Illustration: Figure 26.--Three views of swimming sei whales. In all
three, note the tall, distinctly falcate dorsal fin (which has been
described as sickle or scimitar in shape) positioned farther forward on
the back than the fins of either the fin whale or the blue whale. In the
photo in the middle, note that the dorsal fin has appeared on the
surface while the blowholes are still open. Sei whales, generally
skimmer feeders and rather shallow divers, often show the dorsal fin and
much of the back for relatively long periods as they surface to breathe.
(_Photos from off central California, courtesy of National Marine
Fisheries Service_ (_middle_); _northeast of Hawaii by S. Ohsumi_ (_left
inset_); and _from off Japan by Japanese Whales Research Institute,
courtesy of H. Omura_ (right inset).)]
[Illustration: Figure 27.--A freshly dead sei whale from the Pacific
(top) and a stranded specimen in an advanced stage of decomposition at
Cape Island, S.C. (bottom and inset). Note that even though the
distinctive coloration of the fresh specimen has faded on the rotting
specimen, the numbers and lengths of the ventral grooves (38 to 56 in
number and stopping well short of the navel) still permit the specimen
to be distinguished from fin, blue, and Bryde's whales, in all of which
the grooves extend at least to the navel. (_Photos by Japanese Whales
Research Institute, courtesy of H. Omura (top); and J. G. Mead (bottom
and inset)._)]
[Illustration: Figure 28.--Dorsal view of a sei whale on the deck of a
whaling ship in the North Pacific. Note the numerous scars on the body
and the otherwise dark gray coloration of the back. (_Photo by Japanese
Whales Research Institute, courtesy of H. Omura._)]
[Illustration: Figure 29.--The right upper jaw of the sei whale stranded
at Cape Island, S.C. The baleen plates, here partly buried in the sand,
numbering from 318 to 340 per side and uniform dark gray with fine
lighter gray bristles, continue to serve as identifying characteristics
even on a badly decomposed specimen. (_Photo by J. G. Mead._)]
BRYDE'S WHALE (B)
_Balaenoptera edeni_ Anderson 1879
Other Common Names
None known.
Description
Bryde's whales reach a maximum length of approximately 46 feet (14 m).
They closely resemble sei whales in external appearance. At a distance,
the head of this species is similar in profile and general appearance to
that of the sei whale. The most distinctive field characteristic of the
species, however, is the presence of three ridges along the head
anterior to the blowhole. In addition to the medial ridge characteristic
of all the other balaenopterid species, Bryde's whales have two
secondary ridges on the top of the head--one along each side even with
the blowhole running forward towards the tip of the snout. If they can
be examined at close range, Bryde's whales can be positively identified
by this character alone.
The dorsal fin of Bryde's whales is up to 18 inches (45.7 cm) tall,
extremely falcate, pointed on the tip, located well more than one-third
forward from the tail, and is often irregularly notched or frayed on the
rear margin from unknown causes. Bryde's whales are dark gray overall,
though some individuals, like some minke whales, have a small region of
gray on each side just forward of the dorsal fin.
Natural History Notes
Bryde's whales, like minke whales, reportedly often approach close to
vessels as if curious about them. During this time they may be examined
carefully and their identifying characteristics seen.
Though euphausiids may be an important food for this species in limited
areas, Bryde's whales often feed on schooling fish (including pilchards,
anchovies, herring, and mackerel). This food preference is reflected in
the diving behavior of the species. Bryde's whales are not "skimmer"
feeders; they are deeper divers. When they surface to breathe, they
often rise more steeply to the surface, exposing much of the head, roll
the body sharply, and hump up the tail stock before beginning another
dive. In this species, as in the fin whale, it can be generally stated
that the amount of the back which is exposed above the surface as the
animal sounds is approximately twice the height of the dorsal fin. They
apparently do not raise the tail flukes when beginning a dive.
May Be Confused With
At sea Bryde's whales may be confused with sei whales, fin whales, and
perhaps minke whales.
They may be most readily distinguished from sei whales by the
characteristics discussed on p. 32 and by differences in diving
behavior. The shallow-feeding sei whales surface and blow at regular
intervals over long periods of time. Bryde's whales are deeper divers,
less likely to surface, and blow at evenly spaced intervals. If they are
seen only briefly or at a distance, however, the two species may be
impossible to differentiate.
During the winter months, when fin whales may venture into tropical
waters, they may also be confused with Bryde's whales. But fin whales
seldom exhibit curiosity about boats. In addition, the dorsal fin of the
fin whale is larger, is located farther back on the back than that of
Bryde's whale, and does not become visible as soon after the blow. It is
also less likely to be worn on the rear margin than that of a Bryde's
whale.
The head of the fin whale is more acutely pointed. Furthermore, the
right lower lip and the right front baleen of the fin whale are white.
The baleen and the right lower lip of Bryde's whales are dark gray. If
the animals can be approached closely from the right side, positive
identification is possible using these differences in color.
Like Bryde's whales, minke whales often approach close to vessels. But
minke whales have an acutely pointed snout, a single head ridge, and a
white band on each flipper. Further, minke whales rarely reach 30 feet
(9.1 m) in maximum length.
Distribution
The distribution of Bryde's whales is rather poorly known, no doubt in
part, because the species is difficult to positively identify at sea,
and records of its occurrence may have often been confused with those of
sei whales, fin whales, or minke whales. From stranded animals and
confirmed sightings at sea, the species appears to be found primarily
near shore in areas of high productivity in tropical or subtropical
waters, though it ventures into warmer temperate waters as well. It has
been reported from Virginia south into the northeast Gulf of Mexico and
the southeast Caribbean, and southern West Indies (Curacao and Granada).
To date no migration has been described for the species.
Stranded Specimens