CANBERRA, Nov. 21 (Xinhua) -- The government of South Australia (SA) has revealed a plan to implement a speed limit for boats in the state's dolphin sanctuaries.

Under the plan, boats in the Adelaide Dolphin Sanctuary, a 118.7-square-km area that houses up to 400 wild dolphins, will be held to a speed limit of seven knots (12.96 km per hour).

SA Transport Minister Stephan Knoll made the announcement on Wednesday after a petition calling for the speed limit received more than 20,000 signatures.

Knoll dismissed a 10-knot speed limit in the area as "unworkable" in May but on Wednesday changed his tune.

"The state government has consulted widely and taken into consideration the feedback of all stakeholders on this issue," he told News Corp Australia.

"Port Adelaide is not only our state's busiest port but it's also used by our recreational and commercial fishers, various recreational boating groups and those who wish to enjoy the dolphin sanctuary."

The "Protect Our Dolphins" campaign was launched by Messenger Community News publications, which are owned by News Corp, after four of the seven dolphin calves born in the sanctuary in 2017 died as a result of "blunt trauma".

A report published by the SA Museum found that 17 out of 35 adult dolphins deaths in the region were also a result of blunt trauma.

Mike Bossley, a dolphin expert who has studied the sanctuary for more than 30 years, said that the deaths could have only been caused by boats.