WA’s unique marine world

The longest coastline

With 40% of Australia’s coastline and less than 10% of the population, West Australians have their fair share of Australia’s marine waters. Not only does our coastline stretch more than 12,500 km, it spans over 20 degrees of latitude from 14°S in the north to 35°S in the south, including many different ecosystems. Despite its vast size, some of our marine wildlife traverses our coastline every year. Humpback Whales migrate northwards from the Antarctic Circle up along the WA coast to shelter in Camden Sound (Kimberley Coastline). Here, females give birth and suckle their young for their first few months until their calves are strong enough for the arduous swim back south for a summer of feeding in the antarctic. Camden Sound is crucial habitat for the Humpback Whale, a protected species in Australia.

A curious current

The marine environment of Western Australian is unusual because of the Leeuwin Current, the longest, continuous coastal current in the world. The Leeuwin Current flows down the west coast from the North West Shelf and turns east at Cape Leeuwin flowing past the Great Australian Bight, bringing warm, relatively low salinity and nutrient poor tropical waters along the edge of the continental shelf. This current allows WA’s marine life to be extraordinary because many tropical species occur much further south than usual.

The Leeuwin current from Ridgway and Condie, 2004

Extraordinary and diverse ecosystems

With tropical species dominating the northern waters and temperate species prevailing in the southern ocean, the transitional zone in-between has most unusual communities: at the Abrolhos Islands, temperate seagrasses live beside tropical corals. Incredibly, as much as 10% of the shallow water marine life is only found in WA and much of the rest are Australian locals too.

Marine management planning in WA

At present, there are no functioning regional marine plans in WA. Thus, WA’s marine environment is facing continual demise through small, but ad-hoc decisions by federal, state and local governments. Currently only 2.4% of our state’s marine waters are fully protected, despite multi-use marine parks implemented in nearly 12% of our coastal waters. The federal government has yet to implement National Marine Parks in its offshore waters (from 3 nautical miles out to the EEZ).

The role of fully protected Marine Parks

Fully protected areas (marine sanctuaries) are currently the best management tool for conserving many marine systems because they exclude destructive extractive activities like fishing and mining. To give our marine wildlife a fighting chance for survival, our ecosystems need to exist as close to their natural state as possible.

Locally, direct impacts such as overfishing, dredging, pollution, coastal development and industrialization weaken our coastal ecosystems. Globally, warming seas, acidification of the oceans, industrialised overfishing and loss of fragile marine ecosystems, such as coral reefs, are affecting the health of our marine wildlife.

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