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SEALS: Species --
. Seals,
Sea Lions and Walruses . Grey seal .
Ringed seal .
. Baltic ringed seal . Saimaa seal . East
Atlantic Harbor seal .
. California Sea Lion .
--- Grey seal (Halichoerus grypus)
The grey seal males are
195-230 cm long and weigh 170-310 kg. Females have a length of 165-195 cm
and a weight of 95-105 kg. Pups are at birth 95-105 cm long and weigh
11-20 kg. This is the
seal species with the most pronounced sexual dimorphism. Males are dark
with light patches and have an elongated snout with a wide heavy muzzle.
Females are light coloured with dark spots. Pups are born with a white
lanugo and moult after 2-3 weeks.
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| Picture: Female grey seal. |
Distribution
The grey seal lives in three
separate areas:
- West Atlantic
- East Atlantic (Iceland, Faroes Islands, British Isles, WaddenSea,
Norway)
- Baltic
Habitat
Not much is known of the grey seal habitats outside the breeding season. They are then mostly found near rocky shores and around small islands. They usually breed on rocky shores, but in some areas also on sandy beaches. In the Baltic and in Canada however, the grey seal breeds on the ice.
Feeding
The grey seal feeds on local
inshore fish species, cephalopods and crustaceans. They eat approximately
5-7½ kg per day. Many of the fish species in the grey seals' diet are
commercially exploited, so there is competition for resources with the
fisheries. Grey seals have been seen to
raid the nets of fishing boats and completely empty them. They also do
damage to set nets.
Consequently some seals drown in the nets or are shot by the fishermen. Another concern relating to the fisheries is that the grey seal acts as a host of the cod worm.
Life history
Females become mature at ages 4 to 7 and males at ages over 10 years.
Pregnancy lasts 11½ months. The maximum age for females is 46 years and
for males 26 years. Pup mortality is high. Depending on the location,
34-60% of all pups do not survive the first year.
Population size and status
Several censuses have been carried out of grey seal populations, using land, boat and aerial counts. The West Atlantic stock is estimated at 30,000 animals, of which 17,900 are located in the Gulf of St. Lawrence and 9,400 at Sable Island. The total for the East Atlantic stock is somewhere between 85,000 and 89,000. about 69,00 of which are in the British Isles. The 1995 Baltic population was estimated to consist of 5,300 seals. The grey seal populations in Scotland and Canada are regulated because of the codworm problem. (The codworm is a parasite of the commercially important fish species cod). In the United Kingdom on average 1,000-1,500 pups have been taken annually. In Iceland there is no regulation of the hunt, but annually about 500 pups are killed. In other areas, except the Faroes, the grey seal is protected, but may be shot by fishermen if the seals approach their nets. Only the Baltic stock is still in danger, because of the pollution of the Baltic Sea with organochlorines (DDT, PCB). Also net and fishing gear entanglement is a large problem there.
--- Ringed seal (Phoca hispida)
Taxonomy
Several subspecies of the
ringed seal have been recognized, each with their own specific range.
These are: the North Atlantic ringed seal, Phoca hispida hispida, the
Japanese ringed seal, Phoca
hispida ochotensis, the Bering Sea ringed seal, Phoca hispida
krascheninikovi, the Baltic ringed seal, Phoca hispida botnica, them
Ladoga seal, Phoca hispida ladogensis and the Saimaa seal, Phoca
hispida saimensis. In the following some general information about ringed
seals are given, followed by some more details on the Finnish seals: the
Baltic ringed seal and the Saimaa seal.
Appearance
The ringed seal measures from 85 to 160 cm and weigh 40 to 90 kg. Males are usually slightly larger than females. Pups are 55-65 cm at birth and weigh 4-5 kg. The colour of the coat is dark grey with a grey to black backside with oval white rings. The underside is light grey. Pups are born with a white lanugo and moult after 3-4 weeks.
Distribution
As already indicated above, the different subspecies inhabit different areas. These are:
· Phoca hispida hispida:
Arctic coasts of Europe, the USSR,Canada and Alaska.
· Phoca hispida krascheninikovi: North Bering Sea
· Phoca hispida ochotensis: Kamchatka, Okhotsk Sea and along the Japanese
Pacific coast.
· Phoca hispida botnica: Baltic Sea, Gulf of Bothnia and Gulf of Finland.
· Phoca hispida saimensis: Lake Saimaa, Finland
· Phoca hispida ladogensis: Lake Ladoga, Russia
Feeding
The ringed seal is an opportunistic feeder, feeding on bottom-dwelling organisms, plankton and fish. In winter a large portion of the diet is taken up by polar cod, in summer by crustaceans and invertebrates.
Life history
The ringed seal females become mature at the age of 5-8, males at 6-8. Pregnancy lasts 10½-11 months. The maximum age is about 46 years.
--- Baltic ringed seal (Phoca hispida botnica) *
General information
The Baltic ringed seal is the most common seal in the Baltic. The Baltic ringed seal is on average 140 cm long. Males are about 5 cm longer than females. The females become sexually mature at the age of 3-8 years. Pups are born on the ice of the Baltic in winter. The females build a den in the ice, in which the pups are born. The den has an underwater exit. At birth, they are 60-70 cm long and weight 4-5 kg. The pup stays in the den for 3-4 weeks.
Population size and status
In 1988, the population was estimated to be 6,000-9,000 animals. In 1995, the total Baltic population was about 6,000 animals. Of these, 4,000 lives in the Bay of Bothnia. The Gulf of Finland population is small: 200-300 animals. This sub-population is considered to be endangered. Since 1989, hunting ringed seals is prohibited in Finland.
--- Saimaa seal (Phoca hispida saimensis)
General information
The Saimaa seal is rather unique in that it lives in a freshwater lake system in Finland. In general, they are darker in colour than the Baltic ringed seal and also somewhat smaller. The maximum age is about 40 years. Pups are born in dens in the ice on the lakes. The Saimaa seal feeds mainly on shoaling fish.
Population size and status
In 1983, the population consisted of 100-150 animals. Of those seals, there are 38-40 sexually mature females. The number of pups born each year ranges from 18-26 For 1995, the population was estimated at over 200 seals. The Saimaa seal has been protected since 1955. Its main reproductive areas, Linnansaari and Kolovesi are now protected areas.
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| Picture: (c) Tommi Natri |
Despite the protection, there
are still a number of threats to the Saimaa seal. Especially young seals
are prone to drowning in fishing gear. For that reason, setting nets in
the breeding area during the
breeding season is now prohibited. Also, the habitat of the seal is
threatened by coastline development, especially the establishment of
summer cottages on the Lake. In winter, the use of snowmobiles can disturb
the seals in the dens and may even cause the collapse of a den. And also
pollution of the lakes poses a threat to this rare seal.
--- East Atlantic Harbor
seal (Phoca vitulina vitulina)
Taxonomy
Of the harbor seal, Phoca vitulina, commonly 4 subspecies are recognized: the Eastern Atlantic harbor seal, Phoca vitulina vitulina, the Western Atlantic harbor seal, Phoca vitulina concolor, the Insular harbor seal, Phoca vitulina stejnegeri, and the Pacific harbor seal, Phoca vitulina richardsi. In addition, some authors consider the Ungava seal, Phoca vitulina mellonae, a freshwater seal, as a separate subspecies, but its status as a subspecies is doubtful.
Appearance
The length of males ranges from 150 to 180 cm and the weight from 55 to 105 kg. Females measure 120-150 cm and weigh 45-87 kg. Pups measure 70-90 cm at birth and weigh 9-11 kg. The colour of the harbor seal is variable: grey to brownish grey with black spots. Characteristic for the harbor seal are the V-shaped nostrils.
Distribution
The Eastern Atlantic harbor seal can be found in Iceland, the British Isles and Ireland, in Norway up to the Finmark and into the Barents Sea, in the southern part of the Baltic and in the Wadden Sea and North Sea coasts of Denmark, Germany and the Netherlands.
Habitat
Harbor seals are usually found close to shore. During low tide they haul out on sandy beaches, rocks or tidal flats. In the Baltic, they reproduce only in the southern part, on beaches. It is the only seal in Finnish waters that does not reproduce on the ice.
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| Picture: Harbor seal having a lunch. |
Feeding
The harbour seal feeds mainly on inshore shallow water fish species, such as flounder, sole, herring, cod, whiting and eel, but also on mussels, crabs and squid. They eat 5-8½ kg per day.
Life history
Females become mature at the
age of 3. Pregnancy lasts 10½-11 months. Pups are nurse for 4-6 weeks.
The maximum age in the wild is 35 years for females and 25 years for
males. In the Wadden Sea 60% of the pups do not survive the first year. In
the Danish Kattegat-Skagerrak area, this is 33-52%. The pups can swim
right after birth, which is necessary since the pups are usually born in
areas that are flooded during high tides (beaches, tidal flats).
--- California Sea Lion (Zalophus californianus)
Taxonomy
Three subspecies are recognized: the California sea lion, Zalophus californianus californianus, the Galapagos sea lion, Zalophus californianus wollebaeki and the Japanese sea lion, Zalophus californianus japonicus, each living in a clearly separate range.
Picture: Australian Sea Lion.
Appearance
Males measure on average 220
cm and weigh 275 kg. Females are much smaller: 180 cm and 91 kg. Pups are
about 75 cm long and weigh 5-6 kg at birth. The coat is dark greyish brown
to black. The
males have small manes and an enlarged crest on their heads.
Distribution
Each subspecies has its own range. The California sea lions ranges from the West coast of Mexico to British Colombia. The Galapagos sea lion lives exclusively on the Galapagos Islands. The Japanese sea lion lived in the Sea of Japan, but is now probably extinct.
Habitat
Males form territories in breeding time on rocks and sand or gravel beaches.
Feeding
The California sea lion is an opportunistic feeder: it eats whatever is available. Its main diet consists of herring, whiting, anchovies and squid.
Life history
Despite its popularity as a zoo and oceanarium animal, very little is known about its vital parameters in the wild. The age of maturity andmortality rate are unknown. Pregnancy lasts about 50 weeks and lactation 5 to 12 months. The maximum aged is probably be around 17 years.
Population size and status
There are probably
75,000-100,000 California sea lions, maybe more. The population of
Galapagos sea lions is probably around 20,000animals. They are protected
throughout their ranges and are currently not endangered. In zoos and
oceanaria, they breed well and currently birth control measures are
necessary to prevent overcrowding of existing parks. In Washington state,
some animals are interfering with the salmon runs, which provides them
with an easy meal. Toprevent extinction of some salmon stocks, the US
government has considered killing some sea lions. In the end, Sea World
caught the main salmon eater and kept it. In early 1998, young sea lions
have suffered from food shortages, caused by the El Niño event, which has
driven fish stocks offshore.
Population size and status
There are about 15,000 seals
in the United Kingdom and some 2,000 in Ireland. In Denmark, there are
about 5,000 seals. In Norway there are about 1,000 seals and in Iceland
there may be as many as
28,000. The Baltic population is quite small: about 200 animals.
The Wadden Sea population in 1980 was estimated at 4,000-5,000. In 1987 this had increased to around 10,000 animals. In 1988 a viral infection wiped out a large portion of the Wadden Sea population. The population size after the epidemic was about 3,000 animals, but since then, the population has recovered and was at 7,250 in 1992.
The harbor seal has been hunted in the past throughout its range and in some areas (Iceland and Norway), there may still be some hunting operations. The Wadden Sea and Baltic populations have suffered a lot from pollution, especially with PCBs, which had a very negative effect on their reproduction: the numbers of pups born in these areas have long been too low.