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Salmon experiment puts fish in river water
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SACRAMENTO . (AP) — State fish and wildlife officials are studying a new way of transporting hatchery salmon that are intended to repopulate the Sacramento River system, a newspaper reported.

About 100,000 Chinook salmon have been taken to San Francisco Bay, where they were released, in water actually from the Sacramento River, The San Mateo County Times reported this week.

The theory being tested is that the fish will develop a memory of the water's chemical makeup that will improve their ability to get to the river from the bay to spawn.

Fish and Wildlife biologists have raised concerns that too many hatchery fish are straying and not returning to the river.

The experiment could help boost salmon populations and impact how hatcheries release the fish, the newspaper reported.

"We're hoping that this is the way of the future," said Andrew Hughan, a Fish and Wildlife spokesman.

Salmon are known to develop smell-related memories on their way to the ocean that guide them on their return trip. The process is known as imprinting.

"They know how the water tastes and smells from their river of origin," said Colin Purdy, leader of the three-year study, now in its second year.

But they are also vulnerable on their trip through the river — hence the decision to release them directly into the bay. That decision, however, deprives them of the chance to imprint, a phenomenon the fish and game experiment seeks to re-establish.

Researchers will determine how many of the 100,000 salmon released as part of the experiment return to the Sacramento River. They will then compare that number to the survival and stray rates of two other groups from the same hatchery.