However, in 2006 the sonar counted 93,000 sockeye salmon, while the weir count was 126,000. A Didson sonar placed next to the original Bendix sonar counted 160,000 fish. The escapement goal was 90,000 to 160,000 sockeye.

The new method is intended to figure out not only how many fish are actually returning to the area, but what those fish are, according to Pat Shields, Alaska Department of Fish and Game area management biologist.

"The way sonar works in these rivers, we can't identify the species of fish that is swimming up the river with the sonar, at least not accurately," Shields said. "We can just count all fish, we call them 'targets,' swimming upriver. And what we do is we put a fish wheel on each bank and sample, take the proportion by species, and apply that to the sonar count. In the Yentna River what we've found out is that the species apportionment by fish wheel has been biased low for sockeye."

Shields said that people have identified this as a sonar issue, when more importantly it is a species apportionment issue that has led to chronic under-counting of sockeye. Fish and Game hopes to keep this new system in place for three or four years, and then go back to the sonar system that has been in place for 30 years once that is sorted out to the department's satisfaction.

However, the Bendix sonar will be replaced with a Didson sonar.

The Chulatna, Judd and Larson lakes were chosen for the project because they are the primary producers in the Susitna drainage, said Shields. And the escapement goals were determined with information acquired over the past three years with a mark-and-recapture study that used weirs at the lakes.

"We have data from these lakes and that's how the escapement goals were established, from an analysis of the current data that we have," Shields said.

The department, in partnership with Cook Inlet Aquaculture Association, will have weirs on a total of seven lakes in the Susitna drainage this summer, but the other four will not have separate escapement goals.

There may not be any immediate changes to the management of the commercial fishery as a result of the data that points to more sockeye than previously thought entering the Susitna drainage.

"Some people are asking 'how are you going to manage your commercial fisheries, and other fisheries in-season?' And really there's not an in-season tool that we'll have this year," Shields said.

The listing of the Yentna River as a "stock of yield concern" came with an action plan that restricts the drift fleet on four openings to the southern end of the inlet, below Kalgin Island and the three-mile corridor for four fishing periods, and that plan remains in place, Shields said.

The Northern District setnetters are restricted to one net instead of three from July 20 to Aug. 6.

A Didson sonar will be in place to monitor run strength in-season, so Fish and Game will not be flying blind, Shields said. And the Didson will likely see more fish going upstream, more in line with the projected return to the Susitna River system of 669,000 sockeye this year, compared to a projected return of 344,000 in 2008. The run is not expected to be twice as strong, but Fish and Game is anticipating counting all the fish this year, something that has not been done in the past.

"The Didson does see more targets going upstream," Shields said. "We still have the issue, though, what are those targets? We still need to go out to the fish wheels and apportion out those targets."

Cristy Fry has commercial fished in Homer since 1978. She also designs and builds gear for the industry. She currently longlines for halibut and gillnets salmon in Upper Cook Inlet aboard the F/V Realist. She can be reached at realist468@gmail.com.