Skip to content

Franciscana dolphins and Lahille’s bottlenose dolphins – Argentina

In the southwest Atlantic, off the coast of Northern Patagonia in Argentina, WDC is supporting vital conservation efforts for two rare species of dolphins.

The endemic franciscana is a small river dolphin inhabiting coastal waters of the Southwest Atlantic Ocean (SWAO) from Southeast Brazil (18°25’S) to the North of Patagonia (42°10’S), Argentina. The distribution of the species is not continuous; on the contrary, several studies showed that there are different populations and even subpopulations restricted to smaller distribution ranges. There is no current estimate of all of these population sizes, and information on the distribution pattern within their total range is limited. In Argentina the species is relatively common in the La Plata River estuary, along the Buenos Aires coast, and the Rio Negro estuary, in the northern limit of Patagonia. Incidental mortality is likely the greatest threat to the franciscana throughout its distribution with recent analysis suggesting that levels of bycatch are not sustainable. Based on these results, in 2017, the International Union for the Conservation of Nature (IUCN) classified the franciscana as Vulnerable in the IUCN red list, and it is actually the most threatened small cetacean in the SWAO.

Habitat degradation, prey depletion due to overfishing, ingestion of marine debris, chemical and noise pollution are other potential threats faced by franciscanas. This species share the same habitat as the also small and fragmented bottlenose dolphin populations which are equally vulnerable to the same threats. The coastal populations of bottlenose dolphins in the SWAO have recently been recognized as a distinct subspecies (Lahille’s bottlenose dolphin - T. t. gephyreus). Lahille’s bottlenose dolphins have been among the most frequently observed cetacean species in Argentinean coastal waters. Since the 1980s, however, this situation has changed: research in Argentina has revealed a progressive disappearance of the species along the Buenos Aires province coast, and declining trends in the populations residing in northern Patagonia. In 2019, the subspecies was classified as Vulnerable by IUCN.

Since 2011, WDC has been supporting research and conservation activities in the Río Negro Estuary (RNE) in northern Patagonia undertaken by Fundación Cethus. The RNE waters provide an important habitat for both species and have been identified as the southernmost breeding and feeding site for franciscanas. Research includes visual, acoustic and strandings surveys as well as an educational programme. This work is included under the umbrella of the International Whaling Commission which has established a Conservation Management Plan (CMP) for Franciscana since 2016, and recently a Task Team to provide guidance for the implementation of conservation strategies for Lahille’s bottlenose dolphins.

Objectives

The project aims to contribute to the international conservation efforts to protect the Franciscana and Lahille’s bottlenose dolphin, reduce the threats they face, develop sustainable management measures and protect the environment for future generations, by  means of:

  • Increasing the scientific understanding of both species in Argentina but mainly at the Rio Negro Estuary.
  • Increasing community stewardship and awareness, so local people understand the value of abundant natural resources and are skilled to deliver the conservation work.
  • Supporting coordination of conservation actions with the governments of Argentina, Brazil and Uruguay.
  • Promoting the creation and establishment of El Rincón Marine Sensitive Area in Argentina under the International Maritime Organization (IMO), through providing key data on cetaceans.
  • Establishing land-based responsible whale/dolphin watching using the best practices based on worldwide experience.

Achievements so far

  • We assessed the impact of local activities and fishery expansion - mostly recreational, developing scientific evidence to define conservation strategies in the Río Negro estuary.
  • Our research allowed us to identify the Río Negro estuary as the southernmost breeding and feeding site for the franciscana.
  • We described for the first time the sounds produced by franciscanas in the wild, and developed open-source click detector software that can be used to conduct future passive acoustic monitoring on this species.
  • By comparing pictures from this catalogue with other catalogues of the species, we were able to detect that 12 of these dolphins were also observed approximately 200km west, at Bahía San Antonio, in the Golfo San Matías, by another research team.
  • Sounds produced by Lahille’s bottlenose dolphins have been collected in the Río Negro estuary and Bahía San Antonio. These sounds are being analyzed and will be compared to other populations in Brazil and Uruguay, to help understand population differentiation along the whole range of the subspecies.
  • Our educational program "Delfines del Río Negro" has reached more than 12,000 students and teachers. Outreach was also accomplished through artistic campaigns, beach cleanings, design and distribution of informative brochures and posters.
  • From the beginning of the project we were working to establish land-based responsible whale/ dolphin watching (RWW) using the best practices based on worldwide experience. Local operators and authorities were trained on RWW through a series of workshops.
  • Since the very early stages of this project, we have shared our research with the international research community, and in particular within the International Whaling Commission (IWC) we had an active role supporting the establishment of the Conservation Management Plan in 2016, and the ongoing work under the CMP.

Further Information: Scientific Papers we have contributed to.