Website shows how sonar used to track salmon

FISHERIESJanuary 14, 2012 

Most people don't know that 40 years ago Alaska pioneered the use of sonar to track salmon runs, or that state fishery managers operate 15 sonar sites on 13 rivers from Southeast to the Yukon.

The goal of making Alaskans more aware of one of Alaska's most important fish-counting tools has been accomplished with the launch of a new online project that lets visitors see three types of sonar in action.

The site explains that traditional tools such as weirs and counting towers can be used to count salmon in clear, narrow streams but not in wide, turbid rivers.

"To gauge salmon runs we can't see we have taken a lesson from one of Mother Nature's fish finding experts. In glacial silt-laden bays and rivers, beluga whales find salmon by emitting high pitched calls and listening for returning echoes. Similarly, we have adopted sonar as a tool to detect salmon not by sight but by sound," it explains.

Sometimes conditions are so harsh the equipment can't operate properly, such as at the Pilot Station site on the Yukon River.

"It is a mile wide, and you almost have to imagine sand dunes changing in a windstorm on the bottom," said Debby Burwen, a research biologist with Fish and Game's sport fish division in Anchorage who helped spearhead the project. "But that is where they need to count the salmon because they are trying to ensure that enough fish escape to Canada. In order to do that, they have to know how many fish are coming into the river."

Burwen said people also don't realize that managers never depend solely on sonar information, especially on the more complicated rivers like the Yukon and the Kenai.

The sonar website project provides virtual tours of all 13 rivers as well as radio programs and downloadable brochures. Go to www.alaska fisheriessonar.org.

Fish abundance

This year the U.S. became the first country to put catch limits on every species it manages. That includes all fish and shellfish caught in waters from three to 200 miles from shore. For Alaska, that means 80 percent of the total annual catch.

The outlook this year for both supply and markets is good. Market expert Ken Tally summed it up as "supplies of major species are expected to increase worldwide with prices to stabilize with the strong demand."

Pollock, the world's largest food fishery, is holding steady for the biggest producers: Alaska and Russia. For cod, the groundfish bellwether global fisheries are picking up in the Atlantic and the Barents and Baltic seas. In Alaska, Pacific cod supplies this year are expected to increase 4.2 percent.

Total groundfish catches in the Gulf of Alaska are pegged at 3 percent higher to about half a billion tons. That includes a nice 15 percent increase for black cod (sablefish).

For fisheries in the Bering Sea and Aleutian Islands region, scientists said groundfish stocks could sustain a catch of 2.5 million tons or roughly 5.5 billion pounds in 2012.


Laine Welch is a Kodiak-based fisheries journalist. Her Fish Radio programs can be heard on stations around the state. This material is protected by copyright. For information on reprinting, contact msfish@alaska.com.

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