The rivers on the Kenai Peninsula are shucking their ice much sooner in the past few years than they have in decades, some flowing freely as early as mid-March.

The Anchor River officially became ice-free on March 18, nearly a month ahead of the 30-year average, according to the National Weather Service’s Alaska-Pacific River Forecast Center. The Kenai River did not appear to completely freeze up this winter and is now completely ice-free.

The peninsula only experienced about 40 percent of the normal freezing-degree days as of April 2016, according to the National Oceanic and Atmospheric Administration National Weather Service. Homer recorded a 58-degree day in March.

Fishermen may be delighted; with the lakes open earlier and the water warmer, they have some more time for chances to fish. The lake Alaska Department of Fish and Game biologists in Soldotna use Hidden Lake near Skilak Loop Road as a gauge for the ice on other lakes, and saw its ice recede by the first week of April this year, about a month ahead of schedule, said Jason Pawluk, assistant area management biologist for the Division of Sportfish in Soldotna.

“In general, all the lakes on the peninsula had an early ice-out,” Pawluk said. “A lot of the bigger lakes, (like) Tustumena, Skilak and Kenai, didn’t even freeze over. It isn’t too uncommon, but it happens every now and then.”

Fish and Game biologists were able to start field projects a little earlier this year. Biologists in Soldotna could start rescuing fish from the Soldotna Creek system earlier in the year in preparation for treating the system with rotenone to kill the invasive northern pike, and netting for the pike on Sevena Lake, Pawluk said. Biologists from the Homer office were able to get the weir into the Anchor River a little sooner, said Carol Kerkvliet, the area management biologist for Fish and Game in Homer.

An early breakup may also have some unforeseen consequences. Branden Bornemann, the water quality coordinator for the Kenai Watershed Forum in Soldotna, said one concern is the contraction of the breakup season. In the past, spring melts have stretched out over the course of a month or so, but with higher temperatures in the spring, the snowpack on the peninsula’s lowlands and the ice on the river all melt at once, condensing the breakup season.

He said the effect on salmon in warming streams would be unpredictable because the change is happening so quickly.

“Sure, salmon exist in California in 50- to 60-degree (Fahrenheit) water, but my answer to that would be that they’ve had thousands of years to adapt,” Bornemann said. “Within a century, we might be 5 to 6 degrees Celsius warmer. That doesn’t seem like a big leap, but it’s actually a lot.”

The change in breakup times may also have an effect on the water levels in streams. Sue Mauger, science director for conservation organization Cook Inletkeeper, said the organization tracks both water temperature and level in the Anchor River year-round, as well as in the Deshka River. This year, both the water level and the temperature in the Anchor River are ahead of schedule, she said. The Anchor River was open for much of the winter, and even when it did freeze, the snowpack on top of the ice was low, she said.

“This time of year, we often have really high water and it’s really muddy, and it’s about the time that people think about fishing for king salmon,” Mauger said. “We’re not at really high water right now.”

Cook Inletkeeper keeps its gauges in the river all winter, collecting data about the Anchor River’s water conditions throughout the year. Mauger said the collection of winter data helps fill in the gaps in Alaska’s climate change story.

Bornemann said there has historically been a lack of data for the Kenai Watershed in the wintertime because of ice conditions, so with the reduction in winter ice, researchers might be able to leave their instruments out in the water all winter to collect information. They did not leave them out last winter, though — the risk of ice damaging them could be expensive, he said.

There may also be implications for the fish. Mauger said one change could be in the timing of the salmon outmigration, when the fry leave the rivers for the ocean to feed. With the ice receding earlier and temperatures warming, they could be prompted to exit into the ocean sooner, she said.

“These easier spring melts are easier on the fish, but this time of year is when we usually have our chinook and coho salmon leaving the rivers as fry, so if they’re able to go out into the ocean almost a whole month early, that changes the conditions,” Mauger said.

Pawluk said sonar in the Kenai River has seen some smolt outmigration this year. He said biologists are keeping an eye on the hooligan as well, which they do not quantify in fish counts but are brought to their attention by the fishermen. If this coming weekend does reach up to a sustained 70 degrees, as predicted, they could expect to see some early entry of hooligan into the river, Pawluk said. The sustained warm temperatures could affect the run timing of other fish as well, he said.

“I think it’s safe to say we’re kind of anticipating early run timing for these early runs,” Pawluk said. “Whether or not that will come to fruition, time will tell.”

Some popular lakes to fish are Kelly, Peterson and Watson lakes, all relatively close together on the Sterling Highway in the Kenai National Wildlife Refuge. Hidden Lake is also popular and hosts a population of natural lake trout, Pawluk said.

Fish and Game will also stock an additional 4,000 arctic char into Spirit Lake in the near future, though the date for the actual stocking is uncertain, he said. The William Jack Hernandez Sport Fish Hatchery in Anchorage had some extra arctic char and offered them to Soldotna for stocking. Since arctic char are sensitive to warmer water temperatures, biologists were limited in lake choices and decided on Spirit Lake because it fit their needs, Pawluk said.

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