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Commerson’s dolphins and Peale’s dolphins – Argentina

For over 20 years, WDC has been supporting research undertaken by Fundación Cethus on cetaceans off Santa Cruz province, Southern Argentinean, Patagonia, particularly on Commerson’s and Peale’s dolphins.

Both Commerson’s and Peale’s dolphins occur in the coastal waters of Southern South America and Falkland Islands/ Islas Malvinas. Commerson’s are also recorded around the Kerguelen Islands in the Southern Indian Ocean. Their relatively limited distribution makes them highly vulnerable. They are found along cold temperate waters to sub Antarctic waters, exclusively in the Southern Hemisphere.

Generally speaking, all coastal cetaceans face numerous threats such as bycatch in gillnets, habitat degradation, pollution, seismic exploration and emerging diseases among others. Of the threats mentioned, throughout the project the two main ones that would be affecting Commerson's and Peale's dolphins, as well as other species of cetaceans in the area, are by-catch and seismic exploration. The presence of some of these threats has been cyclical; for example, bycatch in gillnets has increased during the socioeconomic crises in Argentina.

The over-arching aim of this work is to increase knowledge on these and other species of cetaceans of Southern Patagonia to better understand the impact that human threats might have on them and help to find solutions to mitigate these threats.

Additionally, information on stranded cetaceans is collected during beach surveys in the Santa Cruz province. This allows us to have a better idea of cetacean diversity within Patagonian waters by recording not only species that are regularly seen within the area but also rare species such as: spectacled porpoise, Shepherd’s beaked whale, strap-toothed beaked whale, Cuvier’s beaked whale, sei whale and humpback whale, among others. Samples collected from these stranded and dead animals are analysed, and, where possible, a necropsy is performed.

Peale's dolphin

Objectives

  • To estimate population parameters on Commerson’s and Peale’s dolphins in Santa Cruz province.
  • To study the acoustic behavior of Commerson’s and Peale’s dolphins and identify potential impacts of human-made noise on these species.
  • To provide information to better understand cetacean diversity and help develop new conservation programmes for cetacean species in Santa Cruz waters.
  • To provide decision makers with information and assessment to mitigate the threats that these species face.
  • Strengthen existing marine protected areas (MPAs) and/ or create new MPAs for cetaceans along the Patagonian coast, as deemed necessary.
  • Provide the local community with information of the species present in their area in order for them to appreciate those neighboring species and work for their conservation.

Achievements

  • Since July 2001, Commerson’s dolphins have been protected in Santa Cruz province, thanks to a provincial law which created the Commerson’s dolphin Provincial Natural Monument. In 2002, the hunting or intentional capture of individuals of the species was also made illegal.
  • In October 2009, Peale’s dolphins were designated as a Provincial Natural Monument.
  • We have the oldest Commerson’s dolphin photo-id catalog which dates back to 1996.
  • We recorded and characterized for the first time whistles produced by Commerson’s dolphins, and described the echolocation behaviour of the species in Bahía San Julián.
  • Ambient noise levels were estimated in Bahía San Julián and Ría Deseado, allowing us to have baseline information to monitor future changes in these important habitats for Commerson’s and Peale’s dolphins.
  • During our studies in Santa Cruz province we contributed to strengthen the marine protected areas of Santa Cruz province: Reserva natural Cabo Vírgenes, Parque interjurisdiccional marino Makenke, Reserva provincial Península San Julián, Ría Deseado, Bahía San Julián.
  • Through the educational component of the project, different activities were undertaken such as presentations about whales, dolphins and their habitat, beach cleaning and the opening of an exhibition in January 2019 in Puerto San Julián which then moved on to Puerto Deseado with other locations planned for the future.

Further information: Scientific papers we have contributed to.