whalewednesday

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The Sei Whale is identified by a dorsal fin, 38 to 56 ventral grooves (throat grooves that allow their throat to expand during the hug intake of water during filter feeding). Sei whales are also baleen whales, meaning that instead of the common mammal tooth form, baleen whales have plates for filtering foods in and water out, specifically sei whales have two rows of 300 to 380 baleen plates. This whale is known to be 14 to 20 m long and weighs about 20 tons – females are generally 1-2 m longer than males. The sei whale is dark gray or bluish grey on the back and sides with a greyish white area on the ventral grooves of the lower jaw and underbelly.

The sei whale is one of the fastest cetaceans, reaching speeds of up to 50 km/hour. Sei whales have a more regular dive sequence than most others and is known to stay near the surface more consistently. The sei whale normally blows once every 40 to 60 seconds, for about 1 to 4 minutes, and then can dive for 5 to 20 minutes. During the shorter dives, the sei whale rarely descends deeper than a few feet, so its progress can be followed by “fluke prints” or swirls left by the beat of the tail just below the surface. The sei whale seldom breaches, however the dorsal fin and back remain visible for longer periods of time than with other large whales.

Fluke Prints – the path of the unseen whale

Sei whale groups mostly consist of 2-5 individuals, however thousands may aggregate where plenty of food is available. Like the other baleen whales, sei whales feed by skimming and swallowing surface plankton, mainly copepods (tiny marine crustaceans) but also euphausiids (krill, shrimp like crustaceans).

Mating season ranges from November to February in the Northern Hemisphere and from May to July in the Southern Hemisphere. Females generally give birth to a single calf every other year in winter, after a gestation period of 10.5 to 12 months. Although little is known about their breeding habits, some data indicate that sei whale migration is loosely organized around sex, age, or reproductive function. This presumably relates to mating strategies, but at this time nothing is known of their mating habits or calving grounds.

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The sei whale species was intensively exploited worldwide after blue and fin whale stocks have been reduced. In 1980, it was estimated that the Southern Hemisphere population had been reduced to around 24,000 from an initial level of 100,000 or so. In the North Pacific there was a decline from 42,000 in 1963 to just 8,600 in 1974, while figures in the North Atlantic are the most uncertain, although some surveys have suggested a figure around 10,000. Since 1985, the International Whaling Commission has officially halted all commercial whaling of this species. However, today 50 sei whales are killed annually by the Japanese whalers in the North Pacific in Japan’s “scientific whaling” program.

Sei whales inhabit all ocean and adjoining seas except in polar regions, feeding in cold water during the summer and migrating to warm tropical and subtropical waters during the winter. In the western North Pacific, sei whales are most common in the south-west Bering Sea to the Gulf of Alaska, and offshore in a broad arc between about 40 degrees North and 55 degrees North across the Pacific.

In the North Atlantic, sei whales can be found from the coast of Labrador, and along the coasts of Greenland and Iceland. In the East Atlantic, sei whales migrate north to northern waters off Norway, Shetland, Orkney and the Faeroe Islands an occasionally, Svalbard. Sei whales are also present in the Denmark strait

Sei Whale Feeding Frenzy video:

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The North Atlantic right whale, as some of you may already be aware, has been in the news recently as the Canadian Federal Fisheries officials investigate the death of yet another endangered right whale on the Canadian east coast. The department confirmed on Tuesday August 1, 2017 that a whale was found dead in the Gulf of St. Lawrence after washing ashore on the west coast of Newfoundland. In total the carcasses of 10 endangered right whales have been found in the Gulf since June 7 of this year. Jerry Conway of the Canadian Whale Institute in Campobello, NB, said the deaths are disastrous for an already vulnerable species. “We feel there is tremendous urgency,” he said “This has had catastrophic ramifications on the right whale population, this number of whales being killed when we only know of three calves being born this year. It certainly indicates a rapid decline in the population”

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What are the threats to the North Atlantic right whale? North Atlantic populations have been decimated by historical over exploitation by whaling industry. The species get its name from early whalers, who considered them to be the “right” whales to hunt. Their slower pace, the fact that they come close to land, their tendency to float after being killed and their “productivity” in terms of oil made them lucrative whales to target. Today, the species is threatened by ship collisions, entanglement in fishing nets, and separation from calving areas because of shipping traffic. Since the right whale is found in coastal habitats, it is more likely to suffer impacts of human activity than more open-water cetaceans.

The North Atlantic right whale is mostly found along the Atlantic coast of North America, where it is threatened by entanglement in fishing gear and ship collisions. Some scientists believe these whales have already been extirpated from the eastern North Atlantic and now survive only on the east coast of Canada and the U.S.

The right whale is characterized by a symmetrical skill, paired blowholes, and rows of baleen plates for feeding on plankton. Males can reach up to 12.9m, while females can reach up to 18m and weigh approximately 96, 000 kg or 105tons. They are a relatively slow swimmer, averaging about 8 km/hr and typically makes a series of 5 or 6 shallow dives, then submerges for around 20 minutes. Right whales emit a number of low frequency sounds, mostly during courtship. It is estimated that they can live longer than 30 years and up to about 75 years.

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This large whale mostly inhabits temperate waters and compared to other similar sized cetaceans is found more often in coastal waters, especially during breeding season.

Whereas groups of North Atlantic right whales once numbered in the hundreds in feeding grounds, nowadays they usually travel alone or in groups of 2-3 sometimes up to about 12. Groups splinter off for feeding, most likely the result of the sheer quantity of food required for each individual whale. These aggregations are not fixed, and individuals have been observed to change groups. One notable exception is in the Bay of Fundy, where up to two thirds of the remaining population aggregates in the summer to feed.

North Atlantic right whales feed mostly on copepods and krill larvae. About 2200-5500 lbs may be consumed every day. The right whale feeds by swimming through a swarm of prey with its mouth open and the head slightly emerging on the surface. Having filtered the prey with its baleen plates, it drives out the water, dive, and swallows the food, as a process known as skimming.

Females breed about once every three to five years. Gestation is about one year and the single calf is nursed for 9-12 months. Pregnant females migrate to area off the coast of Georgia and Florida to give birth between December and March and then migrate north to their feeding grounds in the Bay of Fundy. Scientists are confident there is at least one other nursery area but have yet to discover it – where these whales mate is also a mystery.

As with other mammals, right whale mothers and their calves display strong attachments, with the calf keeping in close contact with its mother by swimming up on her back or butting her with its head. Sometimes the mother may roll over to hold her calf with her flippers.