Bottlenose dolphins can be found in the sanctuary all year-round. Over the past 20 years, sightings of dolphins have increased, which signifies the importance of this area for the species. In the Adelaide Dolphin Sanctuary, there are about 40 resident dolphins, but up to 400 visitors have been recorded. These visitors likely use areas adjacent to the Sanctuary, such as the metropolitan coast. Some of the Sanctuary's dolphins even travel as far south as Glenelg, and can be often seen swimming in the Patawalonga Lake.
But dolphins are not the only marine mammals within the Sanctuary. Long-nosed fur seal and endangered Australian sea lions haul out on the Sanctuary's breakwaters after they have spent several days at sea foraging for food. It is important not to disturb these animals as they require lots of rest before they return to sea.
The mangroves and saltmarsh within the sanctuary provide vital habitat for juvenile fish. Their roots offer protection from predators and provide a nursery habitat. Stingrays are often found inhabiting the shallow waters and commonly seen species include eagle rays, smooth rays and fiddler rays. Sharks also swim into the Sanctuary on rare occasions.
The Sanctuary is home to many species of birds including some rare and endangered species. Sea birds often seen include pelicans, cormorants, terns, oyster-catchers and ospreys. Between September and March, the Adelaide International Bird Sanctuary National Park in the northern parts of the sanctuary becomes an important feeding ground for migratory shorebirds. Many of these migratory shorebirds travel from as far away as Siberia and Alaska, passing through up to 22 countries as they travel the East Asian-Australasian Flyway to reach the coast of Gulf Saint Vincent.