Peale’s Dolphin Project












From 1992 to 2009 a research project on Peale’s dolphin (Lagenorhynchus australis) was carried out in Cabo Vírgenes (on the eastern mouth of the Magellan Strait, Santa Cruz province The aim is to study the biology and ecology of the species and to come up with strategies as to how to conserve both it and its habitat. Given the oil activity development at the study area, this research project was also accompanied by a study of the potential impact of such activity.

Since 1998, studies of photo-identification on this species are carried out in La Mina, Bahía San Julián, Santa Cruz province, studies that are planned to be complemented with genetic studies.

During field work, behavior, location and distribution of different groups of animals are recorded and the interaction with other species is studied as well. Surveys are also conducted, and dolphins are individually photographed in order to find peculiar characteristics, using the photo-identification technique, so we can gather as much information as possible about the species.

The studies on this species were supported by Dirección de Recursos Naturales del Consejo Agrario Provincial, Prefectura Naval Argentina, Servicio de Hidrografía Naval, Armada Argentina, Universidad Nacional de la Patagonia Austral and Dirección de Turismo of Río Gallegos, and they were funded by WDCS (Whale and Dolphin Conservation Society) and IFAW (International Fund for Animal Welfare and Habitat).

Getting to know Peale’s Dolphin
Its latin name, Lagenorhynchus australis, comes from the Greek lagenos (flask or phial) and rhynchos (nose or beak) making reference to the barely defined beak. The specific name australis comes from the Latin and it refers to its southern distribution.

The common English name, Peale's dolphin, refers to Titian Peale who described this species in 1848 through a drawing made during a North American expedition to Patagonia.

Physical characteristics
Peale’s dolphin is the largest and sturdiest of the dolphins of the genus Lagenorhynchus that inhabit our seas. Males can reach a maximum length of 2.18 m, females 2.10 m, while at birth the calves would measure around one meter. Their average weight is 100kg.

The colour of the back and of the dorsal fin, flippers and fluke is dark gray or black, as well as the head, mouth and throat. The chest and belly are pale in colour, but it gets darker towards the genital area, highlighting a white area in the insertion of the flippers. Peale’s dolphin has a short and not very defined beak. From the caudal peduncle, and beyond, it has a light gray stripe which narrows towards the level of the dorsal fin, ending in a thin line which extends almost to the blowhole.

The well developed and slightly falcate dorsal fin is inserted in the middle of the back. Calves are paler, so they have a more uniform coloring of pale gray.

Distribution
Its distribution is restricted to the southern waters of South America. The northern limit of its range is Valparaiso (33°S) on the Pacific coast, and up to 38°S on the Atlantic coast. To the south, it is found down as far as Cape Horn and the Burdwood Bank (about 57°S). One specimen was found off Miramar, Buenos Aires province (38° 17'S). Sightings further north in the Atlantic were registered at 42ºS, but Peale’s dolphins are more commonly found to the south of Caleta Olivia and Cabo Blanco (47ºS). They are frequently seen in Santa Cruz province, Tierra del Fuego province, the Magellan Strait, the Beagle Channel and on waters around the Malvinas Islands.

Biology and Ecology
The habitat of this dolphin is mainly coastal, being often seen in capes, coves, bays, channels and fjords (such as those of Tierra del Fuego and southern Chile), where they are strongly associated with kelp beds (Macrocystis pyrifera) looking for refuge and food.
Its diet is generally coastal, generalist and possibly opportunistic. Records of its diet show that these dolphins often prey on fishes such as creole cod (Salilota australis), ling (Genypterus blacodes), hake (Merluccius hubssi), longtail hake (Macroronus magellanicus), silversides (Austroatherina sp.), rock bass (Eleginops maclovinus), as well as squid (Loligo gahi), octopus (Enteroctopus megalocyathus), cray-fish (Pleoticus muelleri) and small mysid crustaceans. Peale’s dolphins use different cooperative feeding techniques in which it is common to see them swimming fast on the surface displacing a lot of water, with several individuals swimming in a circle, leaping low, high and on their sides, and tail-slapping, which serve both to stupefy their preys as well as to force them to move in a certain direction, and so corner them.
No obvious migrations have been registered. Very little is known about the reproduction of this species. Births would occur in spring, and females would become sexually mature when they reach a length of 1.90 m.
In the Cabo Vírgenes area groups consist of 1-13 individuals. However, in other areas, groups have been observed of between 30-100 animals. Breathing and diving frequencies are 3-4 per minute, with apnoea intervals of 1 to130 seconds.
Interaction with other species is common, such as the Commerson’s dolphin (Cephalorhynchus commersonii), Southern right whale (Eubalaena australis), great grebe (Podiceps major), Magellan penguin (Spheniscus magellanicus), Magellan cormorant (Phalacrocorax magellanicus), kelp gull (Larus dominicanus), and South American sea lion (Otaria flavescens).

Conservation
During the 1970s and 1980s, records show that many were captured for use as bait for king crab (Lithodes antarctica) and false southern king crab (Paralomis granulosa) in southern Argentina and Chile. Between 1977 and 1979, it is estimated that in this area more than 4,000 dolphins were caught for use in traps, mainly Commerson’s dolphin and Peale’s dolphin. In Chile, some were caught for human consumption.
Fortunately, both countries established conservation measures to reduce these captures. Some dolphins have been caught in gill and other fishing nets used to catch sea bass and other species.
Main threats to Peale’s dolphin are over-fishing, bycatch, the growing oil activity in the species range and the lack of knowledge regarding this species. Peale’s dolphin is listed in Appendix II of CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora), while the IUCN (International Union for Conservation of Nature) classified it in the category Data Deficient, in 2008. Argentina’s Red List considers it to be at low risk, dependant on conservation.

On October 8th, 2009, the Chamber of Deputies of Santa Cruz province declared it Provincial Natural Monument, the highest protection category that can be given to a species, under Article 6 of Law No. 786.