The federal government today listed four key populations of scalloped hammerhead sharks under the Endangered Species Act (ESA).

The National Oceanic and Atmospheric Administration, for the first time in history, gave a shark species federal protections under the Endangered Species Act. The scalloped hammerhead shark is considered globally endangered by the International Union for the Conservation of Nature (IUCN). The species is targeted primarily for its fins but is also killed as "by-catch" in fisheries targeting other species.

NOAA Fisheries listed scalloped hammerhead sharks inhabiting the Eastern Atlantic Ocean and Eastern Pacific Ocean as "endangered." The agency listed scalloped hammerhead sharks living in the Central and Southwest Atlantic and Indo-West Pacific as the less-serious status of "threatened." The federal agency declined to list scalloped hammerhead sharks that inhabit the Northwest Atlantic or Central Pacific.

"This is great news for hammerhead sharks," Jay Tutchton, senior staff attorney with the nonprofit Defenders of Wildlife, said in a prepared statement. "Today's listing is a significant step in the right direction, but there is still much work to be done."

Scalloped hammerhead sharks feed mainly on fish, squid and stingrays. Males grow to about 6 feet in length. The shark and its parts are prohibited from all harvest, possession, landing, purchase, sale or exchange in Florida.

Fish ecologists say the long-term loss of large sharks could create a cascade of ill effects in the ocean's ecological systems. Scalloped hammerhead, white and thresher sharks, for example, are estimated to have dipped some 75 percent over the past two decades. During the same period, their prey, which includes 12 species of rays, skates and smaller sharks, jumped as much as 10-fold, according to some studies.

Photo: School of scalloped hammerheads (Sphyrna lewini), Seawatch.org