White tip reef shark
White tip reef shark

Although marine protected areas (MPAs) are a common conservation strategy, these areas are often designed with little prior knowledge of whether the species they are designed to protect stay in the area or travel outside it.

Currently, the Coral Sea area and its seamounts in north-east Australia are under review to determine if MPAs are warranted. The protection of sharks at these seamounts should be an integral component of conservation plans.

In a study published yesterday, researchers conclude that a Marine Protected Area would be effective in protecting reef shark populations at Osprey and Shark Reef in the Coral Sea, but only if fishing of sharks was banned.

The Australian research team investigated the movements of sharks at Osprey Reef, namely whitetip reef sharks Triaenodon obesus, grey reef sharks Carcharhinus amblyrhynchos and silvertip sharks Carcharhinus albimarginatus.

They found that most individuals showed year round residency at Osprey Reef, although five of the 49 sharks tagged moved to the neighbouring Shark Reef which is 14 km away, and one grey reef shark completed a round trip of 250 km to the Great Barrier Reef. At Osprey Reef adult sharks generally stayed around the north-west corner: the east wall and southern ends were rarely visited.

The Coral Sea region, an area of approximately 972 000 km2, extends east of the Great Barrier Reef Marine Park (GBRMP) to the edge of Australia’s Exclusive Economic Zone. In May 2009, the entire Coral Sea region was declared a Conservation Zone to provide interim protection while the area is being assessed for potential inclusion in the Commonwealth Marine Reserves. Activities taking place in the Coral Sea region, including tourism and commercial and recreational fishing, were allowed to continue.

Since September 2008, there has been a campaign in the Australian community to have the Coral Sea declared a Marine Park. The initial proposal is for a multiple use marine park model for the whole region that promotes sustainable use (where some fishing is allowed), similar to that of the Great Barrier Reef Marine Park. Conservation groups and some scientists have proposed a total no-take model. To date, this no-take proposal has polarized the debate amongst the community and stakeholders.

In the initial proposed multi-use model, our study location, Osprey Reef is listed as a Habitat Protection Zone that would allow limited commercial fishing and recreational fishing.

It is estimated that each year, live-aboard dive boats are directly responsible for generating at least AU$16 M worth of income to the Cairns/Port Douglas region (North Queensland). Of all the Coral Sea reef systems, Osprey Reef has the highest visitation rate by tourism operators, primarily to conduct shark dives. So, the depletion of reef sharks at Osprey Reef would have financial ramifications for tourism in North Queensland. To put this into perspective, in the Maldives, the removal of only 20 grey reef sharks, with a market value of only AU$1 000, caused an estimated loss of AU$500 000 annually in diving revenue.

Further Reading:
Barnett A, Abrantes KG, Seymour J, Fitzpatrick R (2012) Residency and Spatial Use by Reef Sharks of an Isolated Seamount and Its Implications for Conservation. PLoS ONE 7(5): e36574. doi:10.1371/journal.pone.0036574