A banner day on an Alaska gillnetter/University of Alaska Fairbanks photo
Only days after over-seeing the deaths of nearly 90,000 Upper Cook Inlet coho salmon in two commercial drift gillnet openings in the belief the coho run was late and strong, fishery managers with the Alaska Department of Fish and Game have changed their minds.
An emergency order issued Sunday cut commercial fishing time in the northern Inlet in half and restricted drift netters to drift “Area 1” south of Kalgin Island, along with a corridor near the mouth of the Kenai River.
The Area 1 restriction pushes the fleet down into the wide, unconstricted part of the Inlet where it is harder to find the fish.
The emergency order noted a state Sport Fish Division decision to ban bait fishing for coho in the popular Little Susitna River west of Wasilla, and said that “the Little Susitna River coho salmon sustainable escapement goal (SEG) is 10,100 – 17,700 fish.
Recent daily weir counts are below average, and as of Saturday… total passage
through the Little Susitna weir of 1,833 fish projects that the minimum SEG will not be achieved.
“The restrictive actions to commercial fishing in this announcement are intended to reduce the harvest of coho salmon returning to Northern Cook Inlet.”
There remains hope the Little Su could meet its lower goal.
Good days gone so-so
After a Friday count of 738 coho at the Little Su weir coupled with warm weather leading to glacial melt in the Talkeetna Mountains that brought water levels up by more than six inches, biologists were expecting a big Saturday, but the day’s count was a disappointing 416.
It was not an encouraging sign. Coho are notorious for sprinting for the upper reaches of Alaska drainages when water levels rise.
The Deshka River – a tributary to the big, glacially fed Susitna River – saw 1,600 salmon pass the weir there when the water there started rising on Friday, but even though the water went up more than a foot between Friday and Saturday, the Saturday count fell to 1,200.
The big, two-day return did put the Deshka back on track to meet a minimum spawning goal of 10,200, but that is nowhere near guaranteed. The Little Su, meanwhile, lags behind last year at this time. And in 2016, the river fell short of the minimum spawning goal.
The commercial restrictions came just after Andy Couch, a Little Su fishing guide who lobbied Fish and Game to impose drift fleet restrictions last week to protect coho, finally got a response from state Commercial Fisheries Director Scott Kelley saying the nearly 90,000 coho caught by the drift fleet were collateral damage from an attempt to keep Kenai River sockeye escapements low.
Kelley also offered assurances the Little Su and Deshka were on track.
“The primary reason to open commercial drift gillnet fishing to all waters of Central District for those two periods was to harvest available Kenai and Kasilof sockeye salmon surplus to escapement goals,” Kelley wrote, adding that “the offshore-test-fishery (OTF) coho salmon catch-per-unit-effort (CPUE) model projects escapement goals will be achieved at Little Susitna and Deshka rivers.
“The cumulative coho salmon CPUE through July 30, 2017 was the 10th highest CPUE since 1988. A model based upon coho salmon test fishery CPUE indicated a high probability of achieving the Little Susitna River coho salmon SEG (10,100–17,700) and the Deshka River coho salmon SEG (10,200–24,100).”
It remains possible a lot of coho salmon could show up late. Fish are fickle. And high CPUE’s often indicate strong runs. But sometimes, fishermen prove amazingly efficient at finding where fish concentrate or just get lucky and post high CPUEs even when there aren’t that many fish.
“Because fishers preferably operate where they believe there are fish, fishing effort is not randomly distributed, but rather concentrated on good fishing grounds,” fisheries scientist Daniel Gaertner observed in a 2012 paper published by the International Council for the Exploration of the Sea. “This pattern can be expected for schooling fisheries where searching is highly efficient….
“As a consequence, catch per unit effort is not proportional to abundance.Despite its shortcomings, CPUE still remains a simple and attractive index of abundance commonly used for stock assessment diagnosis by international fishery agencies.”
Much the same is true for test fisheries. Sometimes nets just happen to be set in the right place at the right time and post strong CPUEs even when runs aren’t great.
The hope now is that Kelley’s model based upon CPUE indicating “a high probability of achieving the Little Susitna River coho salmon SEG” is right and not an outlier.