| Big sharks now 'functionally extinct': scientist |
|
|
|
|
Friday, March 30, 2007 The overfishing of large shark species off the eastern seaboard of the United States has upset the balance of marine life, a team of Canadian and U.S. scientists says. "We're chopping off the top of the food chain," said Julia Baum of Dalhousie University in Halifax, co-author of a study outlining the huge decline in big sharks over 35 years. Fewer big sharks mean there are more of the fish they once ate, such as the cownose ray. The population of the rays in Chesapeake Bay has grown by 20 times in 30 years, said Charles Peterson, a professor of marine sciences at the University of North Carolina at Chapel Hill and co-leader of a study published in Science on Friday. As the rays increase — they may now number 40 million — they have slashed the populations of bay scallops, oysters and soft-shell and hard clams, Baum said. The century-old bay-scallop fishery is now just a memory. So many sharks have been killed that they are "functionally extinct," which means they can no longer perform their role of controlling middle predators in the marine ecosystem, Baum told CBC News. See complete article at CBC News. |
