LITTLE SUSITNA PUBLIC USE FACILITY -- The parking lot at the Little Susitna River boat launch was nearly full Friday morning and it wasn't even 7 a.m.
Boats lined the shore as more arrived behind pickups towing trailers that rattled down the gravel road to the launch that's only about 40 minutes from Wasilla.
Landon and Haley Chapman dragged their 4- and 5-year-old daughters out of bed early Friday to join the crowds celebrating decent returns of coho salmon to this, one of the biggest freshwater coho fisheries in Alaska but beset by poor returns in recent years.
"My neighbor, he's a state trooper, and he's like, 'You gotta get to the Little Su. They're catching 'em,' " Landon Chapman said.
Biologists say average to slightly better than average numbers of silvers are expected to return to the Little Su and other popular spots like Jim Creek and Knik Arm streams. Managers last week upped bag limits for coho and added a day to the weekend fishery at Fish, Cottonwood and Wasilla creeks.
That steady stream of coho salmon is prompting cries of victory from Mat-Su backers of new restrictions on commercial fishing in Cook Inlet after several years of weak returns that shut down fishing on the river altogether in 2011 and 2012.
But biologists say it's too early to gauge the effect of so-called conservation corridors imposed on the commercial drift gillnet fleet this year by the Alaska Board of Fisheries. Last year's coho returns were solid too, despite a huge commercial harvest. It was just that fishing conditions and run timing made for poor angler success.
"I'll want to have more than one year of data before I come to a conclusion on whether this is helping northern-bound coho salmon," said Pat Shields, the Alaska Department of Fish and Game's Soldotna-based area biologist for commercial fisheries. "Others will disagree."
Valley anglers, guides and members of the Mat-Su Fish and Wildlife Commission in February successfully petitioned the state Board of Fisheries to keep the drift fleet out of the middle of Cook Inlet in the second half of July. The adoption of conservation corridors was intended to get northern sockeye and coho past gillnets while the fleet targeted its big-money fish, sockeye from the Kenai and Kasilof rivers.
Fishing guide Andy Couch credited the new policy with the best coho fishing on Knik Arm streams he's seen in six years.
Silvers also seem bigger this year, Couch said in a newsletter he circulates by email.
"Fish have been in prime shape as well, with seemingly higher percentages of clean salmon with little or no net mark burns," Couch wrote last week. "The fishery has been providing a much appreciated economic infusion for many businesses in the Mat-Su Valley."
The strength of this season's coho returns is surprising given low numbers of "parent" fish counted several years ago and a major flood that scoured streams while those fish were in them, said Larry Engel, a former Fish and Game biologist and borough fish commission member.
This is only the first year for the new corridor but Engel said the changes mark a clear improvement over the former "gantlet" style fishery in which Mat-Su fish had to make it past the fleet.
Roland Maw, executive director of the United Cook Inlet Drift Association, isn't buying it. Maw says there's no indication the corridors made much difference getting more silvers north but it clearly had a chilling effect on the harvest.
"I watched those numbers very carefully this year anticipating this very interview because the folks up in the Valley, they're saying, 'What a good boy I am. Look what we did,' " Maw said. "Well, I'm not sure that much of anything occurred there other than it disrupted some normal fishing patterns. … It certainly took us off our chum and pink harvests."
The conservation corridor starts at the bottom of Kalgin Island, runs east across the Inlet to about eight miles offshore and north to the place the Inlet narrows near Nikiski.
Under the new restrictions, state managers held the drift fleet to half its normal fishing area starting July 21, Fish and Game's Shields said. During the next period on July 24, managers held the fleet out of the middle of the Inlet altogether. Then they kept it out of part of the Inlet one more period, this time to protect Kenai River sockeye, which may also have helped northern-bound coho, he said.
Last year, the drift fleet caught 185,000 coho, according to ADF&G numbers. The catch as of last week was 63,000, with a few more weeks of fishing to go.
The total commercial harvest on sockeye was down a bit too -- about 2.3 million, compared to nearly 2.7 million last year, Maw said.
He called imposing one conservation area uniquely on the drift fleet a "crapshoot" that doesn't take into account the different routes fish take through the Inlet in different years. Some years, winds blow salmon up the west side of Kodiak Island and then along the east side of the Inlet. Other years, they end up near the McNeil River and on the west side.
"To describe some magical little box and say, oh, that's going to fix it -- what a dream," he said.
Coho runs are notoriously unpredictable from year to year, coursing up and down.
But generally, Shields said, 30 years of data from test fishing off Anchor Point and north shows this trend: When northern coho runs are strong, the drift fleet catches more, and vice versa. Last year's northern coho runs were characterized as above averaged and the drift fleet had a strong harvest.
The commercial fleet in total in 2013 caught more than 260,000 coho -- one of the highest tallies in nearly two decades -- but biologists in the Mat-Su still figure they were at the upper end of the Little Su goal they use to make sure enough silvers return to spawn.
"If harvest drives the runs up there, why weren't the runs decimated last year?" Shields said. "I'm not saying the drift fleet doesn't have any impact on northbound stocks -- of course it does. But their coho catch tends to be in relation to the run size."