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September 11, 2004
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Animal Census (6.20.03) - Some scientists want to take an animal census to classify all our furry and slimy neighbors.

Industrialized Fishing (05.14.03) - A study published in the journal Nature reveals that there may be as little as ten per-cent of major marine life left in the sea.

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FishBase – A Global Information System on Fishes

The Rogue River

Sturgeon Page



   07.31.03
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image: Wildlife Conservation Society
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What’s over seven feet long, can possibly live to be 100 years old, is green, and has something called scutes? It's the green sturgeon. They were here before the dinosaurs, but as this ScienCentral News video reports, little was known about these fish until recently.

Ancient Fish

Beneath the surface of the Rogue River in Oregon swims a seven-foot fish older than the dinosaurs.

Green sturgeon "look the same as they did 250 million years ago," says Dan Erickson, conservation fishery scientist for the Wildlife Conservation Society. Green sturgeon do indeed look like they're from another time, with bony ridges called "scutes" along their sides that they use as weapons to escape predators, and whisker-like barbels hanging off the end of their snouts. "It's just an incredible, majestic, large fish."

Until recently, wildlife experts knew very little about green sturgeon or how to protect them. "Most people on the west coast who fish or understand fish know about white sturgeon, but almost nobody knew about green sturgeon," says Erickson. "They’re difficult to catch on bait. White sturgeon take bait readily, but green sturgeon don’t, so the general public and even many scientists knew very little about the species."

image: Wildlife Conservation Society
Erickson set out to learn more about this mysterious fish in mid-2000. "To understand the behavior of green sturgeon in the Rogue River, we decided to use a technique called radio telemetry, which is simply placing a transmitter on the fish," says Erickson. "This tag transmits a radio signal, much like your local radio station." In a boat equipped with an antenna and a radio receiver, Erickson and his team tracked individual fish.

Previously, scientists thought green sturgeon stayed in the Rogue River only long enough to spawn before returning to the ocean. By tracking them, Erickson learned that this is not the case. "To our surprise, green sturgeon entered the river, spawned, and then they stayed in the river for more than six months and then left almost as a group at the same time during November," says Erickson, who published his research in the December, 2002 issue of the Journal of Applied Ichthyology. "This indicates that the species is vulnerable while it's in the river because they're there for such an extended period of time and therefore subject to water quality problems, perhaps poaching, things like that."

Fishing, agricultural pesticides, and development along the river could also be potential threats to the fish. So protecting the Rogue, one of only three rivers in the world where the green sturgeon spawn, will be an important key to managing them. "The public should be concerned about a species such as green sturgeon. They're really a part of the Pacific Northwest," says Erickson. "The Rogue River's been here for 10,000 years and the green sturgeon have probably been in that river for most of that time."

Researchers will continue tracking green sturgeon in hopes of preserving them for another 250 million years. Funding for this research comes from the David and Lucile Packard Foundation.


 
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