Risso’s dolphins are in some ways an unusual species that has not been well studied, mainly due to their preference for deep, oceanic waters but research is now underway on several populations throughout their range. One of the most enigmatic cetaceans, this little-known dolphin has an unusual appearance. Unlike many other dolphins, Risso’s dolphin lack a beak, and the bulbous head rises almost vertically from the upper jaw and blunt snout. The body is robust and powerful, and tapers towards a relatively narrow tail, and a distinct crease runs along the top of the melon. Risso’s dolphin may also be recognized from the extensive lines of white scar tissue that stretch down the sides of the body. Their physical appearance is unique and the numerous scars, from their major prey item, squid, and made by other Risso’s dolphins, give them peculiar markings. The amount of white scarring generally increases with age and older individuals can have a notably white head because of this. These scars, along with unique features on the dorsal fin allow for identification of individual dolphins, although allowance has to be made for them changing over time. Risso’s dolphins are also the only species of cetacean to possess a distinct vertical crease on its forehead; this is more pronounced in calves.
Risso’s dolphins can be highly active at the surface exhibiting a range of behaviours including breaching and spyhopping. They do not generally bow ride, but they can be seen travelling in the wake of ships and surfing in waves. They are generally seen in groups of between 10 and 50 animals, but larger schools, up to 4,000 individuals, have also been reported. There is little information about their behaviour but group dynamics are thought to be fluid as in some other dolphin species, with composition changing over time. Risso’s dolphins generally prefer deeper offshore waters where they feed almost exclusively on squid, and have been seen forming lines when hunting. They can be found associating with other species of cetacean such as bottlenose dolphins and pilot whales.
The Risso’s dolphin is a widely distributed species and can be found in the temperate and tropical zones of all the world’s oceans. Although there is no global population estimate, the species is listed on the IUCN Red List as of ‘Least Concern’ worldwide. Major threats to this species include directed hunts (for example in Japan, the Faroes, Sri Lanka, the Philippines and Taiwan), accidental entanglement in fishing gear, climate change, and noise pollution.
Video: Risso’s Dolphins
In Taiji: The 2017/2018 Drive Hunt Quote allows for 251 Risso’s Dolphins
Risso’s dolphins suffer greatly in Taiji, they are rarely taken for captivity and releases are also very rare. This species is hunted solely for their meat, along with other body parts. When a Risso’s pod is driven into the cove, the nets close and the tarps are drawn over the killing beach and you know their fate is set and that slaughter is now imminent.
Witnessing a pod of dolphins spending their last moments together in fear, frustration, panic and hearing those last few breathes they take as they are pushed under the tarps of killing shore is utterly heartbreaking. There are some moments you just don’t forget from a slaughter or perhaps are unable to forgot … the sounds of the banger boats banging on their poles as they drive the dolphins into the cove, the sound of a dolphin taking its last breathes and the sound of a dolphin thrashing furiously in an attempt to escape death and then the eerie silence that tells you the slaughter is done and that yet another pod has lost its life at the hands of the Taiji fisherman.
I took the majority of the photos above during my time in Taiji in December 2013, with the exception of the one of the police monitoring myself and fellow Cove Guardian, Michelle. During my weeks in Taiji, I witnessed several different pods of Risso’s dolphins slaughtered and not a single dolphin was taken for captivity. Apparently the Risso dolphin meat is a favourite among the locals in Taiji.
The Risso on the Rocks photos are a moment I will never forget. If you would like to read more about the story behind the photos please check out: https://goo.gl/c7byTc