Risso’s Dolphin and Pelorus Jack
Grampus griseus Eats Squid and Bears Their Scars
Pelorus Jack was a famous dolphin who escorted ships through dangerous passages.
Risso's Dolphin (Grampus griseus) is also known as 'The Grampus'. It is a large, sturdy animal (about 10-12ft long) with a worldwide distribution. It is usually seen offshore and prefers to feed on squid.
Risso's Dolphin and the name 'Grampus'
Risso’s Dolphin was probably called ‘Grand Poisson’ by French sailors, which was corrupted to ‘grampus’ by any English-speaking crew. Another ‘Grand Poisson’- grampus - was the Killer Whale, but by the time Risso described his ‘grey dolphin’ to Cuvier in 1812 the sailors’ name was only associated only with the dolphin (Orca had already started to be known as the ‘killer’).
Risso's Dolphin – Pelorus Jack
From early times there were stories of dolphins accompanying sailing-ships on occasions. Most are undocumented, but the story of ‘Pelorus Jack’ is undisputed. He escorted sailing-ships across ‘Admiralty Bay’ – near ‘French Pass’ close to Cook Strait - regularly between 1888 and 1912. He was so reliable and trustworthy that ships would wait for him to arrive before attempting the dangerous passage. At that time, when navigation got a bit tricky, a ‘pelorus’ was used to complement compass readings. ‘Jack’ was so competent at guiding the ships that there was no need of the pelorus, and he became known as ‘Pelorus Jack’. He was the first sea creature ever to have been recognised and treated as an individual – he was given special protection on 26 September 1904.
Pelorus Jack and ‘The Penguin’
On one occasion a drunken passenger (aboard ‘The Penguin’) shot and wounded Jack. The crew were ‘not amused’ and wanted to lynch him there-and-then, but both he and Jack survived the incident. A few weeks after his injury Jack returned to his escort work, but he never went near ‘The Penguin’ again. It is ironic that ‘The Penguin’ was wrecked in ‘French Pass’ a few years after this incident.
Risso's Dolphin – Conservation
Because of their world-wide distribution, and the fact that they usually keep away from the coast, it has been difficult to estimate how many Risso’s Dolphin there are. The species certainly appears on the red list of threatened species, but estimates by the American Cetacean Society are a bit more optimistic. The species is still hunted in some places (not many), but the main causes of mortality (caused by humans) seem to be pollution and accidental entanglement in fishing gear.
Risso's Dolphin - Feeding
Risso’s Dolphin seems to like squid, and the beaks of quite large ones (12 ft – same size as the dolphin) have been found in the stomachs of dead dolphins. Like Sperm Whales these dolphins usually carry evidence of their tussles with squid. It is common to find circular sucker-marks and other scars all over their body – squid do not give up easily!
Ref: An Encyclopaedia of New Zealand
Other articles by John Blatchford
