The Striped Dolphin (Stenella coeruleoalba) is an extensively studied dolphin that is found in temperate and tropical waters of all the worlds oceans. Striped Dolphins can be found in both the Atlantic and Pacific oceans, usually offshore, though sometimes in deeper waters closer to shore.
The ancient Greeks even observed these dolphins in the Mediterraean, and often painted pictures of them.
Striped Dolphin Characteristics
The Striped Dolphin is easily recognized by the dark blue stripe that runs from their dark colored rostrum, around their eye, and down along their side to their rear flank. Another darker patch runs from their melon along their back to their dorsal, ending just behind their dorsal fin, with one portion sweeping forward on the body.
The underside is usually considerably lighter in color – either white or pinkish. Colouration between individuals can vary greatly, with some looking grey in tone while others are more brown. Even within these two colors the tone of the color varies, with some being lighter or darker than others. There is also a dark blue patch around the eyes. The lips are white. The tail stock is the same mid-blue color as the middle stripe of the flank.
By adulthood Striped Dolphins have grown to 2.4 metres (females) or 2.6 metres (males) and weigh 150 kilograms (female) or 160 kilograms (male). Research suggest that sexual maturity is reached at 12 years in Meditterranean females and in the Pacific at between 7 and 9 years.
Striped Dolphin Behaviour
In common with other dolphins in its genus, the Striped Dolphin moves in large groups – usually in excess of 100 individuals in size. Groups may be smaller in the Meditterranean and Atlantic. These Dolphins may also mix with Common Dolphins and might even be confused as a common dolphin from a distance, but they lack the distinctive yellow hourglass shape on the side. Striped dolphins are also generally darker than a Common dolphin.
The Striped Dolphin is as capable as any dolphin at performing acrobatics – frequently breaching and jumping far above the surface of the water as high as 23 feet.
They sometimes approach boats in the Atlantic and Meditterranean but this is dramatically less common in other areas, particularly in the Pacific where it has been heavily exploited in the past.
Striped Dolphin Diet
A widely distributed species such as the Striped Dophin tends to include a high diversity of organisms in its diet. These include a variety of shoaling fish and cephalopods (squid and octopus) concentrating on those species occurring in large dense schools.
Striped Dolphin Communication
Like other dolphins, Striped Dolphins use echolocation, a way of sensing in which they emit high-pitched clicks and sense them as they bounce back off objects (like prey).
Striped Dolphin Reproduction
Gestation lasts approximately 12 months for the female Striped Dolphin and there is a 3 or 4 year gap between calving. Life span of the Striped Dolphin is about 55 – 60 years.
Striped Dolphin Predators
Some sharks (including tiger sharks, dusky sharks and bull sharks) and orcas will prey upon dolphins. Dolphins are also often trapped in fishing nets.
Striped Dolphin Conservation
The Striped Dolphin is an abundant species. It has had some of regional population loses such as the drive fisheries practiced in Japan and the mysterious die off of more than 1000 individuals in the Mediterranean. Fishing industry practices still cause some deaths through entanglement and indirectly impact on some populations by depletion of their food resource.
Striped Dolphin and Humans
Japan has hunted these Dolphins in the western Pacific since at least the 1940s. During the ‘Striped Dolphin drive’ heyday at least 8,000 – 9,000 species were killed each year and in one exceptional year 21,000 individuals were killed.
Since the 1980s, following the introduction of quotas, this number has fallen to around 1,000 kills per year. Conservationists are concerned about the Meditterranean population which is threatened by population, disease, busy shipping lanes and heavy incidental catches in fishing nets.
Attempts have been made to keep the Striped Dolphin in captivity. However these have all failed, with animals dying within 2 weeks due to failure to feed.