Long Beaked Common Dolphin Longbeaked Common Dolphin

Besides what is known about common dolphins in general, little is yet known about the specific behaviour of the long-beaked dolphin (2). Common dolphins are amongst the most gregarious mammals and are sometimes seen in groups of more than 1,000 individuals (4) (6). These large schools may comprise smaller social units of 10 to 30 closely related dolphins (5). At the surface, common dolphins are extremely energetic, moving in and out of the water in a series of high speed jumps, known as porpoising, or leaping vertically to create a dramatic splash on landing (5) (6). Speeds in excess of 40 kilometres per hour can be reached and these dolphins will often ride the bow waves of ships (4) (5). Common dolphins typically dive for two to three minutes in the pursuit of food and can reach depths of up to 280 metres (4). A large geographic range accounts for a diverse mix of prey, that includes various species of small schooling fish and squid (4) (5) (6). Breeding usually takes place between spring and summer, with a sexually mature female giving birth every two or three years. The calf is born following a gestation period of nine to eleven months and is weaned after around six months. The age at which sexual maturity is reached appears to vary with region such that males may take two to seven years and females may take between three and twelve years. The maximum life expectancy is estimated to be around 22 years (4) (5).

The long-beaked common dolphin benefits from The Pacific Offshore Cetacean Reduction Plan which was implemented in 1997 to reduce the number of cetaceans killed or injured incidentally in driftnets. Amongst other obligations, the plan requires that vessels use 'pingers' which send out an acoustic pulse to deter marine mammals such as the long-beaked common dolphin (6). In West Africa, WWF are working to develop an action plan for the conservation of small cetaceans in the region. This plan is to be built around formulating and implementing protective policies and laws, and improving scientific knowledge and public awareness (10).

Since the mid-1990s, the common dolphin has been split into two species, the long-beaked common dolphin and the short-beaked common dolphin (2) (4). As implied by their respective names, beak length is important for distinguishing between the two species, but is not the only defining feature (2). Based on specimens from California, both species have a bold, light and dark hour-glass pattern on the side of the body, forming a V below the dorsal fin, but the colouration of the long-beaked species is noticeably muted. A slightly curved dorsal fin is equally characteristic of both species but the body of the long-beaked common dolphin is more slender and the head is less rounded (2) (5). The long-beaked dolphin has more teeth than any other dolphin with 47 to 67 pairs lining each jaw (6). Although an exceptionally long-beaked form occurring in parts of the Indo-Pacific is sometimes considered to be a separate species, the most recent evidence indicates that it is a subspecies of the long-beaked common dolphin, Delphinus capensis tropicalis (1) (4) (7). There is growing evidence that several scattered populations, currently labelled as long-beaked common dolphins, may have actually evolved independently of each other in response to similar ecological conditions. The implications of this convergent theory are that these populations potentially represent different subspecies of the short-beaked common dolphin, or even unique species. Supporters of this alternative taxonomic view point to the fact that, in parts of the long-beaked common dolphin's described range, it is very difficult to separate the two species of common dolphin on either morphological or genetic grounds (8). Needless to say, more research is needed before the true taxonomic status of this species will be revealed (9).

The long beaked common dolphin is generally found within 180 km of the coast in warm temperate and tropical waters. It rarely occurs near islands that are far from mainland coasts (1) (5).

As the long-beaked common dolphin was only given distinct species status in 1994, its exact distribution in the three major oceans is yet to be fully identified (1) (5). The nominate subspecies, D. c. capensis is known from disjunctive populations on the east and west coast of South America, southern Mexico, central California, West Africa, South Africa, southern Japan, Korea, northern Taiwan and possibly China (1). The less widespread subspecies, D. c. tropicalis, is known only from the northern Indian Ocean and Southeast Asia (5).

Classified as Data Deficient (DD) on the IUCN Red List (1) and listed on Appendix II of CITES (3).

Despite having a smaller distribution than the short-beaked dolphin and probably a far smaller overall population, the long-beaked dolphin is thought to still have a relatively widespread population in the high tens of thousands or even low hundreds of thousands (1) (7). However, in some regions, such as West Africa, East Asia and the east and west coasts of South America, undetermined numbers of long-beaked dolphin are being directly exploited, or taken as incidental bycatch in other fisheries (1). In Peru and West Africa in particular, there is increasing concern about the number of long-beaked dolphin being caught and used for human food and shark-bait (1) (6) (7). Given the lack of data quantifying these impacts, the long-beaked dolphin is currently listed as Data Deficient on the IUCN Red List (1).

The Long-beaked common dolphin (scientific name: Delphinus capensis) is one of two species of common dolphin. Known for its long beak, this dolphin has the most teeth out of any dolphin in the world. Both species of common dolphin are extremely colorful, however, the long-beaked common is typically less brightly colored. In addition to slightly different coloring, beak size, and other physical characteristics; the long-beaked common dolphin differs from the short-beaked in that it prefers more shallow, warmer waters. Also, the long-beaked common dolphin is less abundant than the short-beaked common dolphin. A marine mammal, the Long-beaked common dolphin is a member of the family Delphinidae, part of the order of cetaceans. Thie species name, capensis, was derived from the location of the original specimen for this dolphin, being found on the Cape of Good Hope in the early 1800s. Long-beaked common dolphins have a rounded melon, moderately long beak, and a sleek but robust body with a high, pointed, falcate dorsal fin located in the mid portion of the back. This species can be identified by its distinct bright contrasting coloration patterns. There is a dull yellow/tan thoracic panel between the dark cape and white ventral patch forward of the dorsal fin. The bold coloration forms a crisscrossing hourglass pattern below the dark saddle, and a lighter gray area extends up to the tail stock. Long-beaked common dolphins usually occur in sizable social groups ranging from 100 to 500 individuals, but have been occasionally seen in larger herds of thousands of individuals. These large schools are believed to consist of smaller sub-groups of 10 to 30 animals that are possibly related or separated by age and/or sex.