In 2006 the Commerson’s Dolphin Project (Cephalorhynchus commersonii) completed 20 years of uninterrupted work in Santa Cruz, Argentina. Since 1986 a research project has been carried out on Commerson’s dolphins in Puerto Deseado, Santa Cruz province, during which the movements of 26 identified individuals have been tracked within the estuary. The recorded increase in port activity and boat traffic has made the individuals change their behaviour and movements, growing increasingly timid and locating further up the estuary. The project is sponsored by the Whale and Dolphin Conservation Society (WDCS), and at its beginnings with was supported by the Santa Elena Fishery.
In 1996 a research project was started on Commerson’s dolphins in the region of Puerto San Julián (Santa Cruz Province). With the help of the Argentine Naval Prefecture, the local council and the Honourable Chamber of Deputies, daily monitoring from vessels has enabled 50 individuals to be photo-identified, and there have been sightings of several newborn calves. The aims of the project are:
-  To determine the social structure of the species
-  To determine the feeding strategies
-  To determine the distribution within the bay
-  To implement an environmental education plan within the local community
The animals of Puerto San Julián are extremely active compared with other populations of the same species which are affected by human activity. The first results indicate that throughout the study period rotation exists between the groups which enter the bay.
In January 2000, Fundación Cethus began two new research projects on this species in Santa Cruz province. One of the projects is in Río Gallegos and the other is in Puerto Santa Cruz.

More recently, a genetic study of Commerson’s dolphins of the entire Santa Cruz coast has begun. This project will enable us to evaluate the genetic diversity between the sub-populations of Santa Cruz province, a necessary means in determining the conservation status of the animal populations in order to be able to draw up conservation plans for them. This project is being undertaken with the collaboration of Frank Cipriano, Director of the Conservation Genetics Laboratory of San Francisco State University, USA.

Getting to know Commerson’s Dolphin
Commerson’s dolphin is one of the four species of the genus Cephalorhynchus which only inhabits the Southern Hemisphere. Its common name in Spanish (Tonina overa) refers to its characteristically black and white pattern of colours, and its English name, Commerson’s dolphin, refers to Philibert Commerson who was the first to describe the species in 1767 when crossing the Magellan Strait during his round-the-world voyage as part of Bougainville’s expedition. At a later date, his descriptions came into the hands of Lacépède, who wrote the scientific description in 1804.

Physical characteristics
This species does not exceed 1.5m in length and inhabits coastal waters. Its black and white markings are clearly defined, and the dorsal fin is rounded. The inquisitive nature and “lack of timidity” of this species has attracted the attention and respect of human beings.
Its body is characteristically robust, with a conical head and no distinct beak. It has 28-34 pairs of teeth in its upper jaw, and 26-35 in the lower jaw.

Distribution
Its distribution is restricted to temperate cold and sub-Antarctic waters of southern South America, although there is also an isolated population which inhabits the coastal waters of the Kerguelen Islands in the Indian Ocean.

Biology and Ecology
They generally inhabit shallow coastal waters, moving according to tidal patterns, and are usually found in groups of 1-3 animals, although groups of up to 100 individuals have been seen. They are characterised by their rapid and erratic swimming, their inquisitiveness, and their habit of interacting with boats.
These animals present natural markings so individuals can be recognized and thus kept track of by means of photos. Many of the Commerson’s dolphin populations have already been identified in this way, and various possible options have been presented in order to solve some of the problems which this species has to face. Photo-identification enables many of the mysteries surrounding the Commerson’s dolphin population to be uncovered, including their reproductive biology and social behaviour.
They mainly feed on Fuegian spratt (Sprattus fuegensis), Argentine anchovy (Engraulis anchoita), silverside (Austroatherina nigricans and A. smitii), crayfish (Arthromysis magellanica), squid (Loligo sanpaulensis), longtail hake (Macruranus magellanicus) and krill (Euphasis sp.).

Conservation
Some of the threats confronting this species are related, as with the majority of cetaceans, to being killed in fishing nets, over-fishing, and pollution. For many years they were caught for exhibition in aquariums and as bait for king crab and false southern king crab, although its capture is now prohibited.
The IUCN (The World Conservation Union) considers that there is insufficient information to carry out a direct or indirect evaluation on the risk of its becoming extinct based on the status of its population or distribution, therefore it is classified in the Red Book in the Data Deficient (DD) category.
It is listed in Appendix II of CITES.
In our country, it has been a protected species as from July 2001 in the province of Santa Cruz, thanks to Provincial Law No. 2582, awarding them the status of a Natural Provincial Monument.
From January 1999 to January 2001 more than 70 Commerson’s dolphins have been found washed up in the Gallegos area. Most of these animals bore the marks of fishing nets on their bodies, indicating that they were killed by being caught in these nets.