The Chilean Dolphin is restricted to cold, shallow, coastal waters. According to Goodall (1994) it inhabits two distinct marine regions: (1) the channels from Cape Horn to Isla Grande de Chiloé and (2) open coasts, bays and river mouths north of Isla Chiloé. It seems to prefer areas with freshwater influence, rapid tidal flow, and shallow waters over banks at the entrance to fjords. The dolphins readily enter estuaries and river mouths.

Most sightings have been near shore and therefore the Chilean Dolphin is considered a coastal species, although there has been little survey effort in adjacent offshore waters. Movements appear quite limited, with most dolphins resident in small areas. Individuals identified from natural markings on their dorsal fins have been shown to concentrate their activities in specific bays and channels (Heinrich, 2006). Where year-round studies have been conducted, Chilean Dolphins reside in the same inshore waters throughout all seasons (Heinrich 2006, Pérez-Alvarez et al. 2007). Groups tend to be small (between 2 and 15), but aggregations of 50-60 dolphins, likely representing temporary associations of smaller groups, have been seen along the open coast near the northern limit of the species’ range (Goodall 1994, Pérez-Alvarez et al. 2007). Although mixed groups of Chilean Dolphins and Peale’s Dolphins (Lagenorhynchus australis) have been observed, a clear pattern of habitat partitioning by the two species has been documented based on fine-scale environmental features, with Chilean Dolphins having a notable preference for proximity to rivers and areas of higher tidal flow (Heinrich 2006, Genov, 2012, Viddi et al. 2010, 2015)

Recent genetic studies (Pérez-Alvarez et al. 2015, 2016) have shown that two distinct sub-populations exist: north of Isla Grande de Chiloé (northern coast) and south of Laguna San Rafael (southern fjords). This pattern is thought to be a result of post-glacial range expansion from a northern coastal refuge during glaciation into the southern fjords after the last glacial maximum ~11,000 years ago (Pérez-Alvarez et al. 2016). Fine-scale genetic population structure remains unknown, but it is suspected that substantial structuring might exist between localised sub-populations in the southern fjords where the species seems to be more patchily distributed.

No systematic studies of diet have been made, but anecdotal evidence suggests that Chilean Dolphins feed on shallow-water fishes (e.g., Sardines, Anchovies, Rock Cod), cephalopods, and possibly crustaceans (Goodall 1994).

The Chilean Dolphin is listed in Appendix II of the Convention on International Trade in Endangered Species.

Better information on the status of Chilean Dolphins is needed, especially at the subpopulation level. The species may be declining because of bycatch and the consequences of extensive modification of its limited habitat in southern Chile. Specifically, it is important to obtain abundance estimates, quantitative information on incidental (and possibly direct) mortality, and better information on habitat use in relation to aquaculture and other human activities that may degrade or eliminate these dolphins’ habitat. The rapid expansion of salmon (and shellfish) farming southward in southern Chile is of particular concern. It is also important to evaluate possible gaps in the distribution of Chilean Dolphins to determine the conservation status of various subpopulations.