Mar

29

2007
 
 

Death rays



Sharks. Good if you're a mollusc.With the great sharks gone, the bivalves are in trouble

The more philosophical bay scallops along the eastern seaboard of the United States are no doubt wondering where the big sharks have gone. But a study published today in Science shows why the disappearing predators – great whites, sand tigers, bull and blacktip among them – have had such a catastrophic effect on the musing mollusks. The study’s authors, a collaborative team led by Dalhousie University’s Julia Baum and the University of North Carolina’s Charles Peterson, found that the precipitous decline of great shark populations – driven by the surging global demand for their fins – has allowed seven families of rays, skates and smaller sharks to increase. Cownose rays Rhinoptera bonasus, for example, could now number as many as 40 million. And what do they eat? You’ve guessed it: those poor, thoughtful bivalves.

Source: Myers RA, Baum JK, Shepherd TD, Powers SP & Peterson CH (2007) Cascading effects of the loss of apex predatory sharks from a coastal ocean. Science DOI: 10.1126/science.1138657

Image © Kathy Wynn

Related story in Conservation magazine: Healing powers

Filed Under Endangered species, Restoration, Marine, Monitoring, Economics and conservation | 

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