CETACEOUS AND BIRDWATCHING

In Getari Charter we invite you to make fishing trips to see whales and seabirds.

HARBOUR PORPOISE (PHOCOENA PHOCOENA)

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The harbour porpoise (Phocoena phocoena) is one of six species of porpoise. It is one of the smallest marine mammals. As its name implies, it stays close to coastal areas or river estuaries, and as such, is the most familiar porpoise to whale watchers. This porpoise often ventures up rivers, and has been seen hundreds of miles from the sea. The harbour porpoise may be polytypic, with geographically distinct populations representing distinct races: P. p. phocoena in the North Atlantic and West Africa, P. p. relicta in the Black Sea and Sea of Azov, an unnamed population in the northwest Pacific and P. p. vomerina in the northeast Pacific.

Physical description
The harbour porpoise is a little smaller than the other porpoises, at about 67–85 cm (26–33 in) long at birth, weighing 6.4-10 kg. Adults of both sexes grow to 1.4 m to 1.9 m (4.6-6.2 ft). The females are heavier, with a maximum weight of around 76 kg (167 pounds) compared with the males’ 61 kg (134 pounds). The body is robust, and the animal is at its maximum girth just in front of its triangular dorsal fin. The beak is poorly demarcated. The flippers, dorsal fin, tail fin and back are a dark grey. The sides are a slightly speckled, lighter grey. The underside is much whiter, though there are usually grey stripes running along the throat from the underside of the body.

Populations and distribution
The harbour porpoise species is widespread in cooler coastal waters of the North Atlantic, North Pacific and the Black Sea. The populations in these regions are not continuous[4] and are classified as separate subspecies with P. p. phocoena in the North Atlantic and West Africa, P. p. relicta in the Black Sea and Sea of Azov, an unnamed population in the northwest Pacific and P. p. vomerina in the northeast Pacific. Recent genetic evidence suggests the harbour porpoise population structure may be more complex, and they should be reclassified.

In the Atlantic, harbour porpoises may be present in a curved band of water running from the coast of West Africa to the coasts of Spain, France, the United Kingdom, Ireland, Scandinavia, Iceland, Greenland, Nova Scotia and Newfoundland and the eastern seaboard of the United States. There is another band in the Pacific Ocean running from the Sea of Japan, Vladivostok, the Bering Strait, Alaska, British Columbia, and California. The harbour porpoise has a global population of 700,000. Areas with sizable numbers include the North Sea, where porpoises number about 350,000; the Gulf of Maine/Bay of Fundy area, and the US/Canadian west coast.

SHORT-BEAKED COMMON DOLPHIN (DELPHINUS DELPHIS)

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The short-beaked common dolphin (Delphinus delphis) is a species of common dolphin. It has a larger range than the long-beaked common dolphin (D. capensis), occurring throughout warm-temperate and tropical oceans, including the Indian Ocean although in smaller quantities than other places they are found. There are more short-beaked common dolphins than any other dolphin species in the warm-temperate portions of the Atlantic and Pacific Oceans. It is also found in the Caribbean and Mediterranean Seas. The short-beaked common dolphin is also abundant in the Black Sea, Gulf of Mexico, and Red Sea. They follow the gulf stream up to Norwegian waters. Seldom do any short-beaked dolphin venture near the Arctic.

Physical characteristics

The short-beaked common dolphin is a medium sized dolphin, smaller than the more widely known bottlenose dolphin. Adults vary in length from five to eight feet and range in mass from 100 to 136 kilograms or 220.26 to 299 pounds. Males are generally longer and heavier, with a sexual size dimorphism of 1.06. Mature males also have prominent postanal humps. The color pattern on the body is unusual. The back is dark and the belly is white, while on each side is an hourglass pattern colored light grey, yellow or gold in front and dirty grey in back. It has a long, thin rostrum with 50–60 small, sharp, interlocking teeth on each side of each jaw. Juvenile dolphins have a more muted appearance and become more distinguishable when they mature.

Taxonomy

The short-beaked common dolphin is a member of common dolphin genus, Delphinus, within the dolphin family, Delphinidae. Until the mid-1990s, the different forms within Delphinus were not recognized as separate species, but were all considered members of the species D. delphis.[5][6] Currently, there are two recognized species of Delphinus: the short-beaked common dolphin and the long-beaked common dolphin (D. capensis).[1] The short-beaked common dolphin is generally smaller than the long-beaked common dolphin and has a shorter rostrum. Differentiation among the short-beaked variety can be attributed to ocean temperature, chlorophyll concentration, and ocean turbidity, rather than zoogeographical distribution.

Behavior

Short-beaked common dolphins can live in aggregations of hundreds or even thousands of dolphins. They sometimes associate with other dolphin species, such as pilot whales. They have also been observed bow riding on baleen whales, and they also bow ride on boats. It is a fast swimmer (over 60 km/h), and breaching behavior and aerial acrobatics are common with this species. They are very social animals and engage in most necessary activities such as traveling, eating, and breathing together. They usually associate in groups that can consist of 1000s to 100,000s of individuals. When some individuals are sick, others in the group assist them by using their fins to help keep them afloat so they survive.

Diet

The short-beaked common dolphin has a varied diet consisting of many species of fish and squid that live less than 200 metres (660 ft) deep. The short-beaked common dolphin has been known to eat small fish, such as herring, pilchard, anchovies, hake, sardines, bonito, and sauries, as well as squid and octopus. The diet of short-beaked common dolphins near the English Chanel consist mostly of lanternfish, Atlantic mackerel, sprats, and squids. In the Black Sea, their diet contains sprats, anchovies, and pipefish. In the Mid-Atlantic region near the Northeastern United States, their diet contains of Atlantic Mackerel. They typically eat anywhere from 18 to 20 pounds a day.

In order to study the long-term diet of short-beak common dolphins, their intake of Cadmium (Cd) was osbserved in 2004. It was observed that in oceanic regions short-beaked dolphins diet consist greatly of Cephalopods (such as Cranchids and Histioteuthids). In coastal areas, their diet contained up to 10 times less cephalopods, making cephalopods are more important to the diet of oceanic short-beaked dolphins.

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