Risso's Dolphin
Grampus griseus


Classification
Scientific Name: Grampus griseus

Other Names: Grampus, Grey Grampus, White-headed Grampus, Grey Dolphin

Suborder: Odontoceti

Family: Dephinidae 

Description
Newborn Risso's Dolphins are uniformly grey with a white belly, become olive brown as juveniles and turn a pale grey which, in more mature animals, is often covered by pattern of paler scars.
The dorsal fin is tall and falcate, the flippers are long and pointed and the head is bulbous with a square, abrupt forehead. They are often active at the surface, breaching and spyhopping but seldom bowride. They often associate with bottlenose dolphins and pilot whales.
Maximum Length
Adult: 2.6 - 4 m
Calf: 1.1 - 1.7 m

Maximum Weight
Adult: 300 - 500 kg

Calf: 20 kg

Risso's Dolphin Ecology

Range: Tropical and temperate waters of both hemispheres

Usual Habitat: Generally found in deep waters (generally depths of 400-1000m) just off the continental shelf

Usual group size: 10-30 individuals, sometimes alone, in pairs or groups of 100s

Main Diet: Squid, octopus, cuttlefish and krill

Local population: Unknown

Global range of the risso's dolphin

The dark blue areas indicate where Risso's Dolphins are likely to be found
 Conservation Information
Protection and Conservation Status

IUCN Conservation Status: 
Risso's
Dolphins are listed as "Least Concern" on the IUCN red list.

SPAW Protocol:  Risso's Dolphins are cetaceans, which are listed under Annex II of the SPAW protocol. As such they require total protection under article 11 of this protocol which prohibits the "taking, possession, killing and commercial trade of the species, their parts or products". The SPAW protocol was created to help with the implementation and promotion of the Ramsar Convention and the Convention on Biological Diversity. The Annexes of the SPAW protocol can be found here.

Local Laws: Cetaceans are protected under the Conservation of Wildlife Act of Trinidad and Tobago which offers protection to all species not listed under the second or third schedules of this act.   
Reports of Risso's Dolphins in Trinidad and Tobago
This is currently being researched and written. It will appear here shortly.
  

References
The above information was obtained from the following sources:

  • A Princeton Field Guide: Whales Dolphins and Other Marine Mammals of the World by Hadoram Shirihai and Brett Jarrett (2006)
  • Smithsonian Handbooks: Whales Dolphins and Porpoises by Mark Carwardine and illustrated by Martin Camm (2002)
  • The Whale and Dolphin Conservation Society's Species Guide at http://www2.wdcs.org/species/index.php
  • The IUCN Redlist at http://www.iucnredlist.org
  • The SPAW protocol Annexes with links available at http://www.car-spaw-rac.org/?Annexes-of-the-SPAW-Protocol,83

Acknowledgements
We would like to thank the following people for the use of the art work and photographs:

  • Al√ęsha Naranjit (Illustration of Risso's dolphin)
 
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