Dolphin population at risk

RISK: Local populations of bottlenose dolphins are at risk due to the inverse estuaries in the gulf enhancing effects of climate change.

RISK: Local populations of bottlenose dolphins are at risk due to the inverse estuaries in the gulf enhancing effects of climate change.

Flinders University researchers have warned that ocean warming, noise pollution and fishing pose major concerns for large dolphin populations living in the Spencer Gulf and the Gulf of Saint Vincent.

Marine ecology researchers have said in a new study paper high densities of southern bottlenose dolphins that live in the gulfs are at risk due to little inflow of freshwater.

Lead associate professor at the cetacean laboratory at Flinders University Luciana Moller said the two large South Australian gulfs are inverse estuaries with limited water circulation, enhancing the effects of human influence and climate.

"As a result, the gulfs are particularly susceptible to human induced impacts such as climate change, habitat destruction and pollution, yet high densities of bottlenose dolphins are found in these waters," she said.

"Our study provides abundance estimates for two genetic populations (of dolphins) that can be used...to inform conservation management."

An aerial survey was conducted in 2011 over an area of 42,438 square kilometres within the gulfs and an estimated 3493 dolphins were seen in summer/autumn and 3213 in winter/spring.

Co-lead associate professor Guido J. Parra said this sort of data was needed to assess and mitigate anthropogenic (man-made) impacts, including fishery interactions, coastal zone developments, and oil and gas exploration.

"High densities of bottlenose dolphin are found in coastal gulf water year round, and also in northern gulf waters, suggesting that both gulfs have large areas of suitable habitat for this species," said professor Parra.

"These waters are also where more anthropogenic activities occur and where climate change is likely to have the largest effect."

The study paper is titled 'Abundance estimates and habitat preferences of bottlenose dolphins reveal the importance of two gulfs in South Australia' and has been published in the journal Scientific Reports.