When the genetic make-up of globally distributed marine species are studied, it is often found that there are significant differences between populations. The differences may be so great that what was thought to be one species is actually two.

A recent study into scalloped hammerhead sharks, Sphyrna lewini, shows that although the fish in the Atlantic and Indo-Pacific populations appear identical, genetically they are different. The scalloped hammerhead in the western north Atlantic is actually a new, cryptic, species.

The study concludes that effective management of large coastal shark species should incorporate this discovery. It indicates that the cryptic scalloped hammerhead is less abundant than S. lewini, making it potentially more susceptible to fishery pressure.

Journal Reference: Marine Biology, Volume 148, Issue 5, Mar 2006

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