COMMON DOLPHINS IN CABO SAN LUCAS
We often see large pods of Common Dolphins during our Cabo San Lucas Whale watching tours. There are 2 species of Common Dolphin encountered here in Cabo San Lucas, the Short Beaked Common Dolphin and the Long Snout Common Dolphin. The Short Beaked we often see in large groups that are most often very active, porpoising and transiting very quickly. While they will often approach our vessels, they quickly lose interest and move off. The Long Snout Common Dolphins are usually seen in smaller groups and also can be very inquisitive.
SHORT BEAKED COMMON DOLPHINS INFORMATION
Short-beaked common dolphins are energetic, boisterous animals often seen breaking the water’s surface at high speed and frequently bow-riding in front of large vessels. While previously considered to be one species, in 1994 the common dolphin was separated into short-beak and long-beak varieties. However, the recent (2009) review of the Delphinus taxa by the IWC scientific committee concluded that the long-beaked and short-beaked common dolphins should probably be treated as the same taxonomic unit which shows considerable variation through its large range. (For these and some other cetaceans however, the species concept does not work very well and what this means in conservation terms will need to be given some careful consideration). A subspecies, D. d. ponticus found only in the Black Sea has, however, also been recognised and there are specific conservation concerns about this isolated population.
The common dolphin has very distinctive colouring, forming an hourglass pattern on its side. A yellow panel runs down the front half of both sides, separated from the grey stripe in the rear by a cape of black that forms a saddle just below the dorsal fin. Most individuals have a prominent white patch on the dorsal fin, one characteristic that distinguishes them from the long-beaked common dolphin. The short-beaked common dolphin is slightly stockier than the long-beaked common dolphin, has a more rounded melon and as its name suggests, a shorter beak. The distinctive hourglass pattern and yellow flash on the animal’s side may also be brighter and more pronounced. The short-beaked common dolphin also has a more spectacled appearance with a patch around the eye. Many colour variations exist of the short-beaked common dolphin and at a quick glance it may be confused with the Atlantic white-sided dolphin, though in that species the colour patches are reversed with the tan or yellow appearing on the tail stock.
Short-beaked common dolphins typically travel in large social groups numbering between 10 and 50 animals, and occasionally, thousands of individuals. They are very acrobatic and can often be seen breaching and somersaulting through the air. Entire pods will bow-ride large ships and they are often seen with other marine mammals (sometimes bow-riding the wake of large whales) and feeding seabirds.
The short-beaked common dolphin is found in most tropical and temperate areas of the Pacific and Atlantic Oceans, although it has declined in some areas recently. The cause of the decline is bycatch in illegal driftnets, prey depletion from overfishing, chemical pollution and habitat degradation. In 2008, the IUCN classified the short-beaked common dolphin as of ‘Least Concern’ at the same time as reclassifying the Mediterranean population as Endangered and the Black Sea population as Vulnerable.
- Delfín Común Oceánico
- Male: 2.7m
- Female: 2.6m
- Calf: 0.8m
- Male: 150 kg
- Female: Unknown
- Calf: Unknown
- Small schooling fish
- Squid
LONG BEAKED COMMON DOLPHIN INFORMATION
This species is difficult to distinguish from the more widely distributed short-beaked common dolphin. It too is very acrobatic and can be seen bow and wake-riding in large numbers. Small pods of 10-30 animals will congregate and form herds of hundreds or thousands of individuals. The recent review of the Delphinus taxa by the IWC Scientific Committee concluded that the long-beaked and short-beaked common dolphins should probably be treated as the same taxonomic unit which shows considerable variation through its large range. (For these and some other cetaceans however, the species concept does not work very well and what this means in conservation terms will need to be given some careful consideration.)
Both common dolphin species are slender, with a long distinct beak and a high dorsal fin. The most notable difference, as the name suggests, is the beak, which in the long-beaked common dolphin can be up to 10% of the total body size. The long-beak common dolphin generally has a sleeker, more streamlined appearance and although both species have a criss-cross pattern on their flanks (forming a lighter horizontal ‘hour glass’ pattern), in the long-beaked species the pattern is less distinct and more muted in colouration. In contrast to the dorsal fin of the short-beaked, the white patch is either absent or minimal in the long-beaked. Also, rather than having a patch covering the eye, there is a stripe running from the beak extending to the eye. Long-beaked common dolphins are slightly larger than the short-beaked, and the long-beaked males are slightly bigger than the females. Long-beaked common dolphins also have possibly the highest tooth-count of all delphinids with between 47 – 67 sharp, pointed teeth in each row.
Long-beaked common dolphins are highly gregarious and are often seen ‘porpoising’ at the water surface, breaching and bow-riding. They are also highly vocal and can be heard when they are above the surface of the water. Long-beaked and short-beaked common dolphins can be found living alongside each other in some near-shore waters. However, the long-beaked form seems to prefer shallower and warmer waters and generally lives closer to shore whilst the short-beaked form prefers oceanic waters. Both species feed on a wide variety of schooling fish and squid and are found in large schools, sometimes consisting of hundreds or thousands of individuals. Long-beaked common dolphins are believed to live for approximately 40 years.
The long-beaked common dolphin lives in warm temperate and tropical waters, including in West Africa, Latin America (from Venezuela to Argentina), along the coast from California south to Mexico and along parts of the Peruvian, Madagascan, South African, Japanese and Korean coastlines. Long-beaked common dolphins have a ‘patchy distribution’ but generally occur within 180km of the coast. Classified by IUCN as Data Deficient, the species is widespread and may number in the high tens or low hundreds of thousands. Large numbers are known to have been taken in gillnet fisheries off the coast of California, in the eastern tropical Pacific tuna fishery and in direct hunts in other South American coastal fisheries, but no one knows exactly how many animals are being affected this way, making it difficult to assess the impacts on the species.
- Delfín común costero
- Delfín de rostro largo
- Male: 2.5m
- Female: 2.2m
- Calf: 1m
- Male: 235 kg
- Female: Unknown
- Calf: 17 kg
- Schooling fish (sardines, anchovies etc.)
- Squid