Some Shark Populations Collapsing. By Andrew C. Revkin, NYTimes, June 12, 2008. "Some shark populations in the Mediterranean Sea have completely collapsed... with numbers of five species declining by more than 96% over the past two centuries. 'This loss of top predators could hold serious implications for the entire marine ecosystem, greatly affecting food webs throughout this region,' said the [study's] lead author... at Dalhousie University in Nova Scotia. Particularly troubling, the researchers said, were patterns indicating a lack of females of breeding age, which are essential if populations are to recover even with new conservation measures... The study focused on five species for which there were sufficient records to chart a long-term trend -- hammerhead, blue and thresher sharks and two types of mackerel sharks. The Mediterranean is home to some 47 shark species, and similar declines are presumed to have occurred in many of them."
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