The Alaska Department of Fish and Game predicts that the Upper Cook Inlet will see a total run of 7.1 million sockeye salmon in 2016.

The prediction is more than 800,000 fish greater than last year’s total run, according to Fish and Game records. Last year’s run was slightly higher than the forecast and the latest run on record, with its midpoint landing on July 25.

However, the commercial harvest was less than the 2005-2014 average, landing at approximately 2.6 million sockeye salmon. It is the sixth lowest harvest in the last decade, according to Fish and Game’s 2015 season summary.

The 2016 forecast predicts a commercial harvest of approximately 4.1 million fish, 1.1 million more than the 20-year harvest average. About 1.2 million sockeye are estimated to be taken in other harvests for a total of 5.3 million.

The forecasts are based on a number of models that take into account the number of fry in the freshwater lakes where the sockeye lay their eggs. Fish and Game biologists count the number of fish in a particular age group in any given year and base their predictions for the following year on the size of an age cohort, called a sibling model.

This is not the only model they use, though, said Pat Shields, the commercial area manager in the Soldotna Fish and Game office. The researchers who do the predictions look at a number of models, determine which one is most accurate and use that to calculate the forecast for the following year, he said.

The Kasilof River and the Susitna River are predicted to see lower runs than the 20-year average, with 861,000 fish running to the Kasilof and 372,000 to the Susitna. Fish Creek is predicted to see a higher run than the 20-year average, with 110,00 fish.

However, more than half of the run is predicted to go to the Kenai River — 4.7 million fish. The Kenai River is also the largest source of the king salmon run. The late-run king salmon peak around mid-July as well.

The commercial fishery regulations from 2014-2017 allow an extra 12-hour fishing period per week in the Expanded Kenai, Expanded Kasilof and Anchor Point sections if the sockeye salmon run exceeds 4.6 million fish.

The Kenai River’s weak king salmon numbers and strong sockeye numbers present a problem for Fish and Game in managing the commercial setnet fishery at the river mouth. Because it is a mixed-stock fishery, it’s nigh on impossible to catch just the sockeye salmon and leave the king salmon for conservation, Shields said.

“It really is a challenge for how to reduce harvest of the weak stock and keep your harvest up on the strong stock numerically,” Shields said. “We know it going into the season that we’ll likely be over our escapement in sockeye. The last couple of years you’ve seen that.”

The harvest numbers are calculated mathematically and are a ballpark estimate, Shields said. If the fishing season goes well and all stocks meet their escapement goals, that is likely where the commercial harvest will land.

The later mid-point of the run is noteworthy but not a confirmed trend yet, he said. Salmon runs vary in timing — for example, the king salmon run was earlier than typical in 2015. Multiple environmental conditions affect run timing, so Fish and Game does not have a firm answer on why the sockeye have been running later, he said.

“There’s not a pattern yet that has been consistent enough to say that we’re seeing a shift in later run timing,” Shields said. “Some people are concerned with the ocean warming. That is something we’re keeping an eye on. I wouldn’t say that we’ve seen a consistent significant shift to later runs.”

Reach Elizabeth Earl at elizabeth.earl@peninsulaclarion.com.