Spectacled Porpoise

As with other porpoise species, the spectacled porpoise has no beak. It has small pectoral fins with rounded tips positioned far forward on the body, and a triangular dorsal fin. This porpoise species shows obvious sexual dimorphism between adult males and females, as the dorsal fins in males are much larger and more rounded than those of females.

Records for female length range up to 204 centimetres (80 in), while males may reach 224 centimetres (88 in), which represents the largest specimen documented thus far. The maximum weight for a female was 85 kilograms (187 lb), while a male has been recorded at 110 kilograms (240 lb).

The distribution of the spectacled porpoise is thought to be circumpolar, and it is considered a predominately oceanic species, however occasional sightings and specimens are documented in coastal regions. Evidence from sightings and strandings suggest that the species can be found within cool temperate, sub-Antarctic and Antarctic waters, where water temperatures range between 0.9 and 10.3 °C (33.6 and 50.5 °F).

Little is known about the reproduction of the spectacled porpoise. In the Tierra del Fuego region, studies estimate that young porpoises are born at 100 centimetres (39 in) long in late spring or summer (November to February). No information is available on gestation, lactation, or inter-birth intervals.

The population size and its inter-connectedness across the Southern Ocean is unknown. Research cruises conducted between 1978 and 2004 in the Antarctic resulted in 28 sightings, however these were made in fair weather conditions and porpoises may have been missed during poorer conditions. It is possible that Passive Acoustic Monitoring (PAM) for spectacled porpoises may shed more light on their range and habitat use, however no studies have been conducted to date.