Among the Whales
by Dr. Sarah D. Oktay
Managing Director UMass Boston Nantucket Field Station
I have friends visiting me from the Pacific Northwest and Texas this
weekend and I have enjoyed taking them around the island to the many
places that makes Nantucket so special. One of my favorites is the Nantucket
Whaling Museum, which not only instills wonder at the size and beauty of
whales, but also reminds me that we are especially lucky to be able to view
these animals in the wild around the island. Over the past few years I have
written about several individual species that have either washed ashore or
been seen from local vessels. Nantucket's proximity to popular feeding
grounds and exposure to the open ocean results in it becoming an inevitable
resting place for marine mammals in trouble.
Where once islanders made their living by hunting down these mammoth
creatures, we now marvel at and financially benefit from their presence. A
small minke whale swam into Nantucket Harbor a few weeks ago to both the
delight and consternation of islanders. There is no definitive answer for why
this mammal decided that the middle of August Race week was a good time
to take a jaunt in the harbor. The most likely reason for its foray is that it was
chasing small bait fish into the harbor and didn't realize it made a mistake
until it had practically booked a ticket on the Steamship slow boat. This happens
somewhat frequently with common dolphins that get caught up in the
chase of their prey and soon find they are ricocheting between cuspate spits
along Coatue and the inner harbor shoreline on the south side.
I wasn't surprised to find out that the World Wildlife Fund ranks
Massachusetts as the 10th best place in the world to whale watch. The best
time for whale watching in Massachusetts is from April to October, although
whales have been spotted in Bay State waters as early as mid-March and as
late as early November. Whales migrate to Massachusetts to feed on mackerel,
herring, krill, and other schooling fish that breed in these nutrient-rich
waters. As soon as the cold weather settles in, however, whales travel to
warmer waters to mate and give birth.
Several types of whales migrate to Massachusetts during feeding season.
The most common sightings are humpback whales, which range in length
from 35 feet to 55 feet and weigh nearly 37 tons. Also common are finback
whales, ranging from 45 feet to 70 feet and weighing 40 tons. Minke, right,
and pilot whales are also spotted in Massachusetts waters. On rare occasions,
smaller species, including sperm, beluga, sei and blue whales, have
recorded. Whales seen within 30 miles of Nantucket on local whale watches
or that have washed ashore over the past ten years include finbacks, humpbacks,
pygmy sperm, dwarf sperm, minke, and northern right whales. Over
the past few years I have written about the dwarf (Kogia sima) and pygmy
sperm (Kogia breviceps) whales that beached themselves here just because I
had never heard of either of these until they appeared on our shores.
Common or northern minke whales (Balaenoptera acutorostrata) are
members of the baleen whale family and are the smallest of the "great
whales" or rorquals which include the humpback whale, the fin whale, the
Bryde's whale, the sei whale and the blue whale. The scientific name for
minke whales translates to: "winged whale" (Balaenoptera) with a "sharp
snout" (acutorostrata). Its close relative, the Antarctic minke whale or southern
minke whale (Balaenoptera bonaerensis) shares many traits but inhabits
the waters of the Southern Ocean for most of the year. Minke whales
received their common name from a Norwegian novice whaling spotter
named Meincke, who supposedly mistook a minke whale for a blue whale
(www.nmfs.noaa.gov/pr/species/mammals/cetaceans/minkewhale.htm).
Minkes are relatively small whales with sickle-shaped dorsal fins located
two-thirds of the way back on the body and white bands on their flippers,
Minkes are pretty sleek for whales and typically exhibit no visible breath
(spout). Like all the rorquals, the minke is a fast swimmer, capable of reaching
speeds of 18-24 knots (16-21 mph). The minke can be curious, and has been known to approach ships, even at times keeping up with moving vessels.
Whale observers always look for long-distance cues such as spout patterns
and fluke and tail behavior to identify whales at a distance and the
minke rarely lifts its tail. Our harbor visitor was an excellent example of a
minke and was estimated by Captain Blair Perkins of Shearwater Excursions (one of our many local New England Aquarium stranding volunteers) to be
20-25 feet long. The National Oceanic and Atmospheric Administration
(NOAA) estimates there are 185,000 minke whales in the Atlantic. They prey
on small schooling fish (like anchovies, dogfish, capelin, coal fish, cod, eels,
herring, mackerel, salmon, sand lance, saury, and wolfish) and crustaceans.
The animals grow to about 35 feet and can weigh up to 20,000 pounds. They
live up to 50 years and reach sexual maturity between three and eight years
of age. Minke whales can be very active at the surface, breaching and "spyhopping" (a term for raising their heads vertically out of the water) while
making clicking and, up until recently unidentified, "boing" sounds.
You might recall last year that we had a juvenile humpback whale wash
up on Smith's Point in July. Humpbacks are seen relatively frequently around
Nantucket. Humpback whales (Megaptera novaeangliae "mega" for "giant" and "ptera" for "wing") may grow to be fifty-five feet long and they are usually
black with long white flippers, knobby bumps on their heads and distinctive,
variably sized dorsal fins. These are showy exciting animals on a whale
watch with spectacular breaching maneuvers, exhibiting flamboyant tail lifting
while diving with distinctive black and white patterns underneath. Their
signature bubble net fishing techniques are icing on the cake. During the
spring, summer, and fall, these whales are found most often around the sloping
sides of the banks and ledges of the Gulf of Maine, Georges Bank, and the
continental shelf south of the Islands. Humpbacks are baleen whales that
feed on mostly small schooling fish like sand lance, herring, young mackerel,
and krill. Each whale eats up to 1 1/2 tons (1,361 kg) of food a day.
Because their feeding, mating, and calving grounds are close to shore and
because they are slow swimmers, the humpback whales were an easy target
for early whalers. The International Whaling Commission (IWC) gave them
worldwide protection status in 1966, but there were large illegal kills until the
1970s. Population estimates vary from 35,000 to 70,000 individuals depending
on the source.
North Atlantic Right whales (Eubalaena glacialis which means "good, or
true, whale of the ice") are the most seriously endangered whales with a population
teetering between 400-500 animals. According to a census of individual
whales identified using photo-identification techniques, the latest
available stock assessment data (December 2010) indicates that a minimum
of 361 recognized individuals were known to be alive in 2005. More than 450
North Atlantic right whales are thus thought to exist at present; almost all living
in the western North Atlantic Ocean. Vessel strikes and entanglement in
fixed fishing gear are the two greatest threats to their recovery. They migrate
between their feeding grounds in the Gulf and Maine, the Bay of Fundy, and
in Cape Cod Bay and their calving grounds down south off the coasts of
Georgia and Florida.
North Atlantic Right whales are stocky (they prefer big-boned) mostly
black whales with no dorsal fins and rough white patches called callosities on their heads. They can be identified at a distance from their
spouts which appears as a V-shaped pattern of water vapor due
to their partitioned blow holes. When they dive they usually lift
their black, triangular tail high. They eat zooplankton, including
copepods (tiny crustaceans), euphausiids (small shrimp-like
crustaceans), salps (gelatinous tunicates) and cyprids (barnacle
larvae). Unlike other baleen whales, right whales are skimmers:
they feed by removing prey from the water using baleen while
moving with their mouth open through a patch of zooplankton.
Our other local cetacean denizen is the fin whale
(Balaenoptera physalus), also called the finback whale, razorback,
or common rorqual. Finback whales can be up to 80 feet
in length and their dorsal fin is very far back on their dorsal
(back or upper) side. They are the second longest animal in the
world and the second in size after the Blue Whale. Finbacks are
grayish, sleek whales with tall, curved dorsal fins. Their heads
are asymmetrical with darker markings on the left side and
lighter marking on the right side. The reason for this unusual
coloring is unknown, but some scientists have speculated that
fin whales circle schools of fish with the white side facing the
prey and frightening them into denser schools that are easier for
the whale to catch. Other scientists theorize that this lighter
color is mostly pointed downward as they swim on the right
side to feed. Of course a few have to swim on the left side just
to mess with that theory. Similar to the minke whale, finbacks
rarely lift their tails while swimming. Like other baleen whales,
fin whales have two blowholes positioned in a V-shape while
toothed whales have only one blowhole. They have a broad,
flat rostrum (upper part of the head). Their throat grooves or
ventral pleats, in addition to streamlining their shape, allow
their throat area to expand tremendously during feeding. In the North Atlantic, they prey on krill and small schooling fish (e.g. capelin, herring,
and sand lance) which they can scoop up while swimming on their sides
at speeds from 6-10 mph while side-feeding and up to 25 mph while lunging into balls of fish.
Fin whales were severely overhunted in the 19th and 20th centuries and
are still hunted by commercial vessels from Iceland and Japan and aboriginal
subsistence vessels from Greenland. Estimates suggest that the population
of the remaining fin whales in the all the world's seas range from less than
100,000 to roughly 119,000. As with many whale species there is a division
of species between northern and southern hemispheres. The fin whale that
inhabits the North Atlantic is the Northern fin whale, (Balaenoptera physalus
physalus) which is smaller than and distinct from the southern fin whale
(Balaenoptera physalus quoyi). Fin whales are more gregarious than other
rorquals, and often live in groups of 6–10, although feeding groups may reach
up to 100 animals.
Another relatively common marine mammal visitor is the long finned
Pilot whale (Globicephala melas). Like the orca, the long-finned pilot whale
is really a dolphin (Delphinidae family). Six of the larger species in the
Delphinidae, the Orca and the Pilot (long-finned and short-finned), Melonheaded,
Pygmy Killer and False Killer Whales, are commonly called whales,
rather than dolphins; they are also sometimes collectively known as "blackfish."
A female pilot whale beached itself twice and eventually died in June
of 2011 near Smith's Point. Pilot whales are often involved in mass strandings
off of Cape Cod. During the summer of 2000, there was a mass stranding
of 11 pilot whales on Nantucket on the 4th of July. The weather was clear
and calm and the animals showed no obvious underlying health problems as
opposed to other mass strandings that can be linked to storms or unusually
high or low tides. From the New England Aquarium (NEAQ) website: "The
term "mass stranding" refers to events in which groups of distressed
cetaceans (whales, dolphins, porpoises) come ashore alive. They can involve anywhere from a few to several hundred animals. Mass strandings regularly
occur in several parts of the world (primarily Australia, New Zealand and
Cape Cod), yet so far we have no universally accepted, comprehensive explanation
for this syndrome. In many cases, the animals show no obvious signs
of health problems other than those resulting from coming ashore. Although
mass strandings typically occur during winter months and at times of severe
weather, they can occur at any time of year and under any conditions. Once
a cetacean comes ashore, a cascade of physiological changes occurs, often
resulting in shock and death. Because the species typically involved are
extremely social, the bonds that hold groups together are perhaps strong
enough to supersede the survival instincts of individual animals. Although
we don't know what specifically might set off a mass stranding event, we
know that once animals start coming ashore, it's extremely difficult to stop
the process from continuing and escalating. Affected animals will relentlessly
follow one another ashore, as if crippled by widespread panic, even when
there is clear access to open water. Gregarious offshore species such as
Atlantic white-sided dolphins (Lagenorhynchus acutus) and long-finned pilot whales (Globicephala melaena) are particularly known to mass strand in New
England, mainly on Cape Cod." Sometimes it does not pay to be one of those
friendly party people.
It is important to remember that all marine mammals are protected under
the 1972 Marine Mammal Protection Act. This year marks the 40th anniversary
of this critically important legislation which has ensured that our children
and grandchildren will be able to see these creatures in the wild.
The New England Aquarium (NEAQ) oversees the Nantucket Stranding
Team volunteers on island and local volunteers go through extensive NEAQ
training before they are allowed to work with the team. The aquarium is
authorized by the National Oceanic and Atmospheric Administration's
Fisheries Service to respond to marine mammal strandings of whales, dolphins,
porpoises and other animals. Anyone spotting a stranded marine
mammal on Nantucket is urged stay away from the animal, and to call the
NEAQ's 24-hour stranding hotline at (617) 973-5247.