Research shows why shark nets took such a heavy toll on dugongs

A James Cook University team monitored dugongs moving between Hervey Bay near Bundaberg and Moreton Bay near Brisbane.

Scientists suspected dugongs navigated between the two bays close to the shoreline, but this had been impossible to establish before recent advances in GPS tracking.

JCU’s Professor Helene Marsh said of the four dugongs that made the roughly 300km journey, three stayed within 5 km of the coast.

“We suspected the dugongs would stay near to shore and the new research proves it. It shows us why shark nets were so much of a problem. They were deployed close to the shore and when they were first introduced in the 60s the dugong kill was very high. For example, 82 dugongs were killed off Townsville in the first year of netting.”

Professor Marsh said the problem had diminished since the replacement of shark nets with drumlines at most locations in the Great Barrier Reef, and the opening of dugong protection areas from the 1990s onward.

Thirty-nine dugongs were recorded drowned in shark nets in Queensland from 1989 to 2011.

However, Professor Marsh said she is concerned about the planned introduction of shark nets in northern NSW.  Dugongs are listed as an endangered species in NSW.

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