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Harbor
Seal
Phoca vitulina richardii
Class: Mammalia
Order: Carnivora
Suborder: Pinnipedia
Family: Phocidae (earless seals or true seals)
General
Natural History
Phoca vitulina means "sea calf," or "sea
dog." Harbor seals are widely distributed throughout
temperate and arctic waters of the northern hemisphere. Harbor
seal are the most common and widely distributed pinniped in
Washington waters. They are frequently sighted by boaters,
ferry passengers and other users of the marine environment.
This relatively small, stocky seal is considered a non-migratory
species, breeding and feeding in the same area throughout
the year. In water, harbor seals use their hind flippers for
propulsion, while on land their method of locomotion is a
caterpillar-like undulation utilizing their fore flippers
for momentum.
Male and
female harbor seals are of similar size (to 250 lbs.) and
coloration. Coat (pelage) color is typically a light
colored base pelage with dark spots although some individuals
have a reversed pattern of mostly black or dark brown with
white spots. Occasionally a "red coat" harbor seal
may be seen. The red pelage coloration may result from deposits
of precipitated iron oxide on the hair.
Harbor
seals generally do not live longer than thirty years although
captive seals have been known to live up to thirty-three years.
Females tend to out live males and both genders incur their
highest mortality rate during the first few months after birth.
Harbor
seals and other marine mammals are at the top of the food
chain and frequently have high concentrations of various pollutants
in their blubber (subcutaneous fat) layer. High concentrations
of chemical compounds like PCBs and DDT have been demonstrated
to negatively affects the health of harbor seals and other
marine mammals, the WDFW is continuing this research which
it began in the 1970's
FOOD
Harbor seals are opportunistic feeders. Their diet varies
from one area to another and throughout the year depending
on prey availability, and includes: a wide variety of fishes
and cephalopods,. They generally feed close to shore or in
shallow waters, and may feed at specific or preferred sites
on a regular basis. Seal may actively feed in fresh water
(rivers and lakes) connect to estuaries. Seals have been observed
feeding during daylight hours as well as night.
HABITAT
Harbor seals may inhabit shallow areas of estuaries, rivers,
and places where sandbars, beaches, or rocks are uncovered
at low tide. Harbor seals use a variety of sites to rest or
"haul-out" along coastal and inland waters these
include: intertidal sand bars and mudflats in estuaries, intertidal
rocks and reefs, beaches, log-booms, docks and floats in most
marine areas. They prefer gently sloped beaches and low lying
flat spots since unlike their cousin the sea lion, a seal
unable to rotate its hind flippers underneath its body.
Marine
mammals, including harbor seals, are protected under the Marine
Mammal Protection Act of 1972 (http://www.nmfs.noaa.gov/prot_res/laws/MMPA/MMPA.html)
therefore it is illegal to hunt, harm or harass any species
of marine mammal in U.S. waters. Many fish species consumed
by harbor seals are also commercially fished, and through
interactions with fisheries seals can become entangled and
drown in fishing nets or harmed by different type of gear.
Further, human generated beach trash, such as strap banding
used on cardboard boxes.
Pups
and Pupping
Pups are born in the spring and summer and the timing of the
peak birth period varies from area to area. Pups are born
along the coast Oregon during in mid-March; along the coastal
estuaries of the Columbia River, Willapa Bay, and Grays Harbor
from mid-April through June; Olympic Peninsula coast from
May through July; San Juan Islands and eastern bays of Puget
Sound from late June through August; southern Puget Sound
from mid-July through September; and Hood Canal from August
through January. Females produce one pup per year, beginning
at age four or five. The majority of pups are born at protected
haul-out sites but a female may give birth anywhere that there
is easy access to the waters edge. Pups are precocious at
birth, capable of swimming and following their mother into
the water immediately after birth. Nursing pups remain with
their mothers for about 4 to 6 weeks and then are weaned to
forage and survive on their own. A nursing pup may triple
its birth weight by the time it is weaned and uses its stored
fat reserves as it learns to feed on its own. Pups frequently
call to their mother with a sheep like "m-a-a-a";
adults make a variety of sounds including. Grunts, growls
and barks.
Table1. Distinguishing characteristics of Pacific pinnipeds.
| CHARACTERISTIC |
Harbor
Seals |
CA
Sea Lions |
N.Elephant
Seals |
| Ears |
"hole"
(no flaps) |
external
flaps |
"hole"
(no flaps) |
| Hind-flippers |
lack
flexibility |
rotate
under bodies |
lack
flexibility |
| Vocalizations |
seldom
(pups only) |
loud
"bark" |
"bull"
sound |
| Pup's
body shape |
football |
elongated |
football |
| Whiskers |
shorter |
long/prominent |
shorter |
| Sand
"flipping" |
none |
some |
regularly |
| Coat
("pelage") |
spotted
coloration |
uniform
coloration |
uniform
coloration |
Average
adult
male weight |
80
kg
(175lbs) |
350
kg
(750 lbs) |
2400
kg
(5000 lbs) |
Average
adult
male length |
1.5
m
(5 ft) |
2.4
m
(8 ft) |
4.5
m
(15 ft) |
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