Murdoch University researcher Professor Neil Loneragan says Marine Protected Areas (MPAs) are still needed in Western Australia despite evidence that fish stocks are healthy.
Professor Loneragan, Chair in Fisheries Science said a joint research project by the Department of Fisheries and Murdoch University, revealed fishing has not significantly altered marine food chains.
“Our report analysed data from commercial fisheries in Western Australian from 1976 to 2005 and covered four major fisheries management zones in the state from Mandurah to Kalbarri,” said Professor Loneragan.
“The report found that although the species composition of the catches had changed, few detectable changes were found in the food chains, or the biomass of fish and their average size.
“No evidence was found over these large areas that the marine food webs had been significantly altered by fishing, which contrasts with some findings in other parts of the world, where the removal of top predators by fishing has resulted in changes in the food webs.
Professor Loneragan said that although food chains can be maintained over large geographic areas, depletion of certain fish stocks still occur in localised areas.
“We have seen this in the snapper stocks of Shark Bay and Cockburn Sound and more recently in dhufish and pink snapper in the metropolitan waters off Perth.”
“The Department of Fisheries has responded to these localised depletions by introducing closures and other restrictions on catch to rebuild stocks in Shark Bay and Cockburn Sound, and closing the metropolitan waters to commercial fishing and limiting the catch by recreational fishers in this region.”
Professor Loneragan said that State and Federal Governments have had and will continue to have a commitment to establishing MPAs around Australia to protect and conserve the marine environment and its biodiversity, particularly those areas that are an important component of sustainable oceans management.
“The primary purpose of sanctuary areas in MPAs is for biodiversity conservation and not fisheries management. These areas are an important component of sustainable oceans management,” he said.
“The protection of biodiversity through MPAs is an insurance policy to enhance resilience in the face of human impacts, particularly climate change.
“They also increase the scope for multi-purpose management of marine areas and provide reference areas to help us understand how the marine environment is responding to a range of influences from fishing to climate change.”
The study was funded with a grant of $576,510 from the Commonwealth Government’s Fisheries Research and Development Corporation (FRDC) and ran for five years.