This summer has been hot and dry in Alaska — so hot, in fact, that even the fish are feeling it.
All over coastal Alaska, temperatures have hovered significantly greater than normal. The state began sweltering in mid-June and crested on July 4, with Anchorage hitting 90 degrees Fahrenheit and Bethel reaching 91. The bright, sunny days brought Alaskans out to swim and recreate, but they also left the waters where salmon were returning exposed to the direct, unforgiving heat.
Shallower lakes and rivers across Southcentral and Southeast Alaska were the first to heat up. In the Matanuska-Susitna Valley, lakes like Larsen and Judd, where the Alaska Department of Fish and Game operates weirs for sockeye salmon, reached 80 degrees. The Kuskokwim River in western Alaska registered water temperatures about 10 degrees greater than normal, likely contributing to a reported salmon die-off as the fish headed upstream.
On the lower Kenai Peninsula, the Anchor River hit its warmest temperature on record on July 7: 73 degrees. It’s dropped since then to about 66.2 degrees, but the spike was troubling, said Sue Mauger, a scientist with Homer-based conservation nonprofit Cook Inletkeeper. The lack of rain has contributed to the temperature increases too.
“I think (the snow) melted out fast,” she said. “It takes a really long time for that volume of water (after a rain event) to warm up again … a rain event can be really significant in these streams.”
Mauger runs a network of stream temperature monitors on 48 creeks around the Cook Inlet watershed through Cook Inletkeeper. Of the four streams she monitors in real time — the Anchor, the Russian River, the Deshka River and Crooked Creek, near the Kasilof River — all have been above normal temperatures except for the Russian River. Though the Russian is a clear water river, it’s likely buffered by its connection to two large, deep lakes at higher elevations near Cooper Landing.
The Deshka’s elevated temperature — more than 81 degrees Fahrenheit on July 7 — was troubling to more than just people. July is normally the height of the king salmon return to the Deshka, but from July 1 to 9, a total of 13 individual king salmon passed the weir, according to Fish and Game. Numbers increased afterward, with nearly 2,000 passing from July 11 to 17, but soon plummeted again.
ADFG has also closed fishing for silvers on the Deshka and Little Susitna rivers until the end of September.
“As soon as the temperature dropped a little bit, hundreds were coming in,” she said. “Clearly, we are seeing the behavior of holding in cooler water.”
In Prince William Sound, managers reported having slow escapements of pink salmon but reports of large aggregations of fish milling in the salt water, which made it difficult to plan fishing periods, as the management systems are based on inriver escapement.
Prince William Sound does not currently have any offshore test fisheries to gauge salmon return indices in the marine waters for fishing periods, so managers and fishermen were stuck waiting for salmon to be ready to head up the creeks.
The one exception has been glacially fed creeks. Not only are water levels relatively normal or high on glacial river systems, their temperatures are also closer to normal. The Copper River experienced record water levels on both ends of the spectrum this year — it was the lowest recorded level ever when Fish and Game put in the sonar in the spring and it hit its highest level ever later in the year — but the temperature has been relatively closer to normal, said Stormy Haught, a research biologist with the Fish and Game commercial division in Cordova.
“Any glacial streams are doing much better than groundwater, rainfall streams,” he said. “Part of it is snowpack; we’ve had a lot of hot weather so there’s just not a lot of source for these streams. Copper River has been high and doesn’t seem like any major temperature anomalies this year.”
The groundwater and snow-fed systems are low, and some are simply drying up. In Prince William Sound, dewatering is relatively normal for some systems; on Montague and Hinchinbrook islands, some short streams can dry up even in wet years, Haught said. However, even normally stable creeks are experiencing extremely low water levels.
In Southeast, the Stikine River’s most recent discharge level was below the 25th percentile, according to the U.S. Geological Survey; the Situk River near Yakutat is below its lowest recorded discharge level, as of Monday.
Most of Southcentral and Southeast Alaska are officially in drought stages, according to the National Integrated Drought Information System. About 21 percent of the state is abnormally dry, but not officially in a drought, while some areas in southern Southeast are in extreme drought as rain continues not to fall.
In Cordova, a city that usually receives about a dozen inches of rain even in the summer months, public works officials have been urging people not to water their lawns, wash their cars or water down the dust on the dry roads.
Public Works Director Samantha Greenwood said it’s a game of trying to keep up with the salmon processing plants, which are now receiving some of their largest deliveries of pink salmon all year. The processors can use millions of gallons of water per day to keep up with operations, and the city can only process so much a day.
“I send an email to the processors, who’ve been great at trying to turn water off whenever they can,” she said.
As of Aug. 19, fishermen in Prince William Sound had harvested about 30.2 million pink salmon in one of their strongest weekly harvests so far this season. But as the sun continues to shine, Cordova’s reservoirs are dropping now, unable to be recharged by lakewater. The city’s website asks residents to conserve water as much as possible.
Upstream, with the low water levels and high temperatures, salmon may be entering a difficult environment. In Bristol Bay, salmon die-offs were reported in the Igushik River in June, likely due to hypoxic conditions as salmon packed into the river and would not pass upstream through pocket of warm water. As more salmon pack into less water, they deplete the oxygen supply and can suffocate.
Because pink salmon tend to spawn low in the river systems or in the intertidal zone, they may do fine in Prince William Sound, Haught said.
“The beauty of salmon is that they have these (variable) life histories, and that’s what helps them survive these environmental events,” he said. “That said, yeah, it’s fairly ugly out there. A fish can’t swim into a stream if there’s no water.”
Mauger said it’s hard to know if salmon will have spawning success, even if they were counted on weirs — there may have been enough water downstream, but maybe the spawning grounds were cut off or too shallow.
The low water levels are also leaving gravel bars — prime salmon spawning habitat — high and dry, she said. And if the water levels continue to drop after salmon have laid their eggs, exposed eggs will dry out and die as well.
Cook Inletkeeper produced projections for water temperatures in different case scenarios for climate change in 2004, projecting out to 2069. This summer saw the Deshka’s water temperature crest above what the models predicted would happen by 2069, Mauger said, putting the temperature increases 50 years ahead.
“I think it’s important that people realize that this is the new reality of where we are and where we’re headed,” she said.
Elizabeth Earl can be reached at [email protected]