--- Baiji (Lipotes vexillifer)

The baiji, white flag dolphin or Yangtze river dolphin is the probably most endangered of the cetacean species. This freshwater dolphin species is limited to the Yangtze river. The main threats for this species are pollution, disturbance by increased boat traffic, habitat destruction (construction of dams) and entanglement in fishing gear. Very little is known about this species. Most of the data about the biology of the baiji comes from the study of a single captive male, named Qiqi, which has been kept at a facility in Wuhan since 1980 and is still alive.

Length: males: 1.41-2.16 m., females: 1.85-2.53 m.

Weight: males: 42-125 kg, females: 64-167 kg

Appearance: The baiji is a stocky animal, with a long, flattened snout. The blowhole is placed slightly left of centre. It is blueish-gray on the back and white on the belly. The dorsal fin is a triangular rise in the middle of the back. The flippers are small and wide.

Distribution: only occurs in the Yangtze river in China.

Social structure: Usually found in pairs, sometimes in larger groups

Feeding: exclusively fish

Abundance: less than 300

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--- Beluga (Delphinapterus leucas)

Together with the narwhal, the beluga or white whale belongs to a separate toothed whale family, the Monodontidae. Sailors used to call this cold water whale the sea canary, because this whale is
highly vocal and produces high-pitched whistles, that could be heard through the hulls of (wooden) ships. The beluga was originally thought to be a coastal species, but recent studies have revealed
that belugas travel long distances over deep water and even through the pack ice, swimming from breathing hole to breathing hole. They are excellent divers and can easily dive to depths of 900 m.

Length: males 4.5-5.5 m, females up to 3.5-4 m. The belugas in the Hudson Bay and White Sea are considerably smaller (3-4 m) than the ones from Greenland

Weight: males up to 1,600 kg (Hudson Bay and White Sea belugas: 300-400 kg)

Appearance: snowy white, extremely stocky, fat animal with a relatively small head. The melon is very bulbous and highly mobile: it distinctly moves when the whale vocalizes. Young animals are dark grey and turn white when they mature. The beluga has no dorsal fin, but has an elevated dorsal ridge. The flippers are short and wide and the tail flukes are broad. The beluga has an unusually flexible neck.

Distribution: Arctic Ocean and adjacent seas. The beluga is often found in shallow waters and estuaries.

Social structure: sometimes small pods (10-20 animals) but they often aggregate into large herds of several hundreds of whales.

Feeding: wide variety of food species, including fish, molluscs and annelids (worms), mostly bottom-dwelling species.

Abundance: total world population is probably about 60,000 animals.

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--- Dall's porpoise (Phocoenoides dalli)

The Dall's porpoise is a fast swimmer and an avid bow-rider. When swimming, they splash a lot, creating so-called rooster tails of water. There are 2 types of Dall's porpoise, which were originally considered to be different species: the dalli-type and the truei-type. The Dall's porpoise has been by-caught in the US salmon fisheries. In 1982 more than 4,000 Dall's porpoises were killed in this driftnet fisheries. Changes in fishing gear and techniques has reduced this by-catch to 741 animals in 1987 and less than 30 animals/year in the 90s. This porpoise is still hunted in Japan for its meat. Every year about 15,000 Dall's porpoises are killed.

Length: 1.8-2.1 m

Weight: 135-220 kg

Appearance: The Dall's porpoise is a very stocky animal, with small flippers and flukes. A ridge leads from the dorsal fin to the tail flukes. The dorsal fin is pointed and triangular. The flippers are very small and rounded at the tips. The small flukes are almost pointed at the tips. This species is jet-black with a variable white patch on the flanks and the belly. The tips of the dorsal fin and tail flukes are also white. There are 4 different colour varieties: all black (dalli-type) striped (dalli-type)
with white side patch below and behind the dorsal fin (dalli-type) with white side patch extending from the flippers to the mid-tail stock region (truei-type)

Distribution: The Dall's porpoise is found in the North Pacific, from Japan and Baja California in the south to the Bering Sea in the North.The dalli-type is found throughout this range, the truei-type is found from Japan to the Kurill Islands only.

Social structure: Usually in small groups of on average 5-6 animals. Feeding: The Dall's porpoises feeds on a variety of prey species, including squid, capelin, Pacific hake, mackerel, blennies, herring and sardines. They may be feeding in deep water.

Abundance: probably between 800,000 and 2,300,000 animals.

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--- Harbour porpoise (Phocoena phocoena)

The harbour porpoise is the only whale species occurring in the Baltic Sea. It is occasionally seen in Finnish waters. In the Baltic, the harbour porpoise has declined severely as a result of pollution
(PCBs). In many areas, the harbour porpoise is now being threatened, because large numbers (many thousands per year) get entangled in fishing gear and drown. Investigations on ways to reduce
this mortality are underway but have not shown any marked result yet (among others at the Fjord & Bælt Centret in Kerteminde,Denmark).

Length: 1.4 to 1.9 m.

Weight: 55-65 kg

Appearance: dark grey back, sometimes brownish, converging to light grey on the belly. The flippers are small and rounded. The dorsal fin is triangular, which is characteristic for nearly all porpoise species. The head is blunt, with no prominent beak. The harbour porpoise is one of the smallest whales.

Distribution: coastal waters of the North Atlantic and the North Pacific. Also found in the North Sea, the Kattegat and the Baltic Sea.

Social structure: usually single, in pairs or in small groups

Feeding: fish (herring, cod), squid and crustaceans

Abundance: unknown. In several areas, the population is believed to be threatened, due to high incidental mortality in fisheries.

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--- Killer whale (Orcinus orca)

The killer whale is sometime referred to as the wolf of the seas. This whale got its name from its group attacks on other marine mammals, including whales much larger than themselves. There have been no reports of attacks directed towards people. Once people were exposed to killer whales in oceanaria, it became clear that the name killer whale was not justified: this whale hunts to eat. In oceanaria the killer whale can peacefully coexist with other marine mammals, like dolphins.

Length: males on average 8.2 m, maximum 9.5 m, females up to 7.3 m

Weight: males 3,600-5,400 kg, females 1,400-3,600 kg

Appearance: back and pectoral fins are black, the belly and the underside of the tail flukes are white and there is white patch around the eyes. There is highly variable grey "saddle" patch behind the
dorsal fin. The body is robust and torpedo-shaped. The pectoral fins are large and paddle shaped. The dorsal fin is hook-shaped in females. In males, the dorsal fin can be very large, up to 2 m.

Distribution: Killer whales are true cosmopolitans and can be found in virtually all oceans and
major seas. Usually they are found within 800 km from the coast.

Social structure: they usually live in groups (pods). The group size varies per region.

Feeding: fish (herring, salmon), marine mammals and birds

Abundance: 70,000 in the Antarctic, about 7,000 around Iceland and the Faeroese islands. Unknown in other areas. Not endangered.

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--- Narwhal (Monodon monoceros)

With its large tusk, the narwhal is one of the most remarkablelooking whales. The function of the tusk has been the subject of speculation. It has been suggested that the tusk is used in sexual
and dominance display or possibly in foraging (digging in the bottom). Like the closely related beluga, the narwhal is very vocal and produces predominantly pulsed sounds. The narwhal has been
hunted by the Inuit people of Baffin island for centuries for its meat and muktuk (skin with attached blubber layer, which is a local delicacy and an important source of vitamin C for the Inuit). Currently a maximum of 542 narwhals may be taken by the Inuit each year.

Length: 4-4.5 m, males slightly larger

Weight: 900-1,600 kg

Appearance: The most prominent feature of the narwhal is the large tusk of adult males, which may grow to 2.4 m in length. This tusk is an extended tooth in the upper jaw. The narwhal has only 2 teeth in the upper jaw. In males one (the left one) grows into the tusk, the other one usually does not erupt. Very rarely narwhals are found with two tusks. The body is rounded and stocky, with a small head. The skin is blue-grey in young animals and brown-grey in adults, with leopard-like spots on the back. There is no dorsal fin, but a series of bumps on the dorsal region. The flipper are small and rounded and usually curled up at the tips. The tail flukes are pointed and have convex trailing edges, which is unusual in whales and dolphins.

Distribution: The narwhal is one of only two whale species that spend their entire lives in Arctic waters (the other species is the bowhead whale).

Social structure: usually small groups (4-10 animals) which sometime aggregate into larger herds. The groups are all male or all female.

Feeding: squid, halibut, cod and shrimp

Abundance: about 29,000 in the Canadian Arctic, 2,600-4,300 in NW Greenland, no data for other areas.

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--- Pantropical spotted dolphin (Stenella attenuata)

The pantropical spotted dolphin is often seen associating with schools of yellowfin tuna. Fishermen made use of this association by setting nets around the dolphins, thus catching dolphins and tuna.
The dolphins were discarded. Large numbers of spotted dolphins, and to a lesser extent common and spinner dolphins, were killed in the tuna fisheries, especially in the Eastern Tropical Pacific (ETP). From 1959 to 1972, between 350,000 and 650,000 dolphins were killed per year in this fisheries. Changes in fishing gear and methods have helped to reduce the dolphin by-catch. From 1986 to 1990, 51,200 dolphins were killed each year (33,900 spotted dolphins, 12,400 spinner dolphins and 4,900 common dolphins). In 1992, the pantropical spotted dolphin bycatch was about 6,500 and in 1993 and 1994 about 2,000 per year.

Length: males: 2.00-2.23 m., females: 1.87-2.07 m.

Weight: 90-120 kg

Appearance: At birth, this dolphin is unspotted, with a strongly defined cape, a flipper stripe ending at the mouth and a tail stock with a dark upper part and a lighter lower part. Spots appear first on
the belly and later light spots appear on the back. The dark spots on the belly increase in size and number and merge in some areas. The same happens to the light dorsal spots. There is a lot of regional variation in colouration and spotting. Coastal dolphins are in general more heavily spotted than oceanic dolphins. In some areas, such as Hawaii, the spots are barely visible.

Distribution: tropical and some tropical waters worldwide.

Social structure: Group sizes vary from a few animals to several thousands per group. Females with calves tend to group together and non-reproducing females are usually found in groups without adult males. Young animals form small schools or join schools of spinner dolphins.

Feeding: small fish, squid and crustaceans. Pregnant females may have different feeding habits from those of lactating females.

Abundance: In the Eastern Tropical Pacific, there are probably about 2,000,000 pantropical spotted dolphins. Little is known about this species in other areas.

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--- Sperm whale (Physeter macrocephalus)

The sperm whale is the largest of the toothed whales. With its asymmetrically placed blowhole and large head it is easy to recognize. A large part of the head is taken up by the so-called spermaceti organ, which consists mainly of fat. It probably plays a role in buoyance control. The enormous amounts of oil in the head made the sperm whale a desired target for whalers worldwide. The sperm whale has been hunted long and extensively. In the peak year, 1964, 29,255 sperm whales were killed. The sperm whale lives in deep waters and can dive to great depths, probably beyond 3 km.
The dives can last 60-90 minutes, although the average dive lasts about 10-20 minutes. Sperm whales produce short series of clicks, often called codas. The click patterns in these codas are probably unique for each whale and can be used to identify individual whales.

Length: males up to 18.5 m, females up to 12 m

Weight: males 32-45,000 kg, females up to 16,000 kg

Appearance: The head is large and rather square. It takes up about 1/3 of the total body length. The skin is rippled and brownish to blue-grey in colour. The area around the mouth and the belly are
distinctly lighter. The single blowhole is placed on the left side, on the leading edge of the large head. There is no dorsal fin, but instead a number of bumps along the tail stock. The flippers are small. The sperm whale has large teeth in the lower jaw only.

Distribution: Worldwide, except in polar waters. Along the Eastern Atlantic coast, the males go as far north as Northern Norway, whereas females don't come North of 45-50N. In summer, sperm whales can be observed off the Lofoten Islands, Norway.

Social structure: Most of the time, there is segregation of the sexes: there are breeding groups of sexually mature females and juveniles of both sexes and male bachelor groups. The males only join the breeding groups in the mating season. The size and composition of the groups varies. Occasionally, several groups come together in large herds.

Feeding: Sperm whales feed at great depths, mainly on large squid. They also feed on fish, including cod.

Abundance: Probably about 1.9 million worldwide, the majority in the Pacific and the Southern hemisphere. The North Atlantic population is probably about 190,000.

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--- Vaquita (Phocoena sinus)

The vaquita or Gulf of California porpoise, is considered an endangered species because of its low numbers and its very limited range. Up to 1990, 30-40 vaquitas were killed in fishing nets each year. Most were killed in the fisheries for totoaba. Although the fisheries for totoaba (an endangered fish species) was banned in 1983, illegal fisheries continued. Other fisheries were started in the same area, which also resulted in vaquita by-catches (10-15/year). The vaquita is the most endangered marine cetacean and is considered to be in immediate danger of extinction.

Length: 1.2-1.5 m

Weight: 30-55 kg

Appearance: The vaquita is lead-gray on the back and grayish white on the belly. There is a dark colouring around the mouth. The dorsal fin is much larger than in other porpoises. The flippers are small and broad and located in the lighter body area. Distribution: only in the northern part of the Gulf of California, Mexico.

Social structure: usually seen alone or in groups of up to 4 animals.

Feeding: fish, including grunts and croakers.

Abundance: no more than a few hundred.

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