An Endemic Species
The Chilean dolphin (Cephalorhynchus eutropia) is a small, robust cetacean found exclusively in the cold, shallow coastal waters of Chile. Adults typically measure up to 1.7 meters in length and weigh around 60 kilograms, with a stocky body shape where the girth can be up to two-thirds of its total length. This unique build, along with a blunt head and a rounded dorsal fin, often causes them to be mistaken for porpoises. Their coloration is a complex mix of grays, with a darker back and lighter sides, and distinct white patches on the throat and behind the flippers.
These dolphins are endemic to Chile, ranging from Valparaíso (33°S) south to Cape Horn (55°S). They show a strong preference for habitats less than 20 meters deep, often staying within 500 meters of the shore. The sheltered fjords, channels, and estuaries of the Chiloé archipelago and southern Patagonia are core areas for the species. Unlike migratory cetaceans, Chilean dolphins are believed to be relatively sedentary, with local populations remaining in specific areas year-round. Their diet consists mainly of small schooling fish like sardines and anchovies, as well as squid and crustaceans. They often hunt in small groups, using circular or zig-zag patterns to herd their prey. The total population is estimated to be in the low thousands, and the species is classified as Near Threatened by the IUCN.
Acoustic World and Industrial Threats
Chilean dolphins communicate using high-frequency clicks, whistles, and cries. Their vocalizations are part of a group of cetaceans that use narrow-band high-frequency (NBHF) clicks, which are thought to be an adaptation to avoid detection by predators like killer whales. Studies in different parts of their range, including the waters around Chiloé Island, show variations in their acoustic signals. This suggests that, like other dolphin species, they may have regional dialects or accents influenced by their specific environment and social groups.
The dolphin's coastal habitat increasingly overlaps with Chile's massive salmon aquaculture industry, the second-largest in the world. This industry poses multiple threats. Underwater noise from boat traffic and farm operations can interfere with the dolphins' ability to communicate and navigate. Entanglement in anti-predator nets surrounding salmon pens is a direct cause of injury and mortality. The high concentration of fish farms leads to localized pollution from excess feed and feces, which can deplete oxygen in the water, creating "dead zones" on the seabed and altering the local ecosystem. Escaped salmon can also compete with native species for food resources, further impacting the dolphins' prey availability.