The combination of low snowpack, lack of spring precipitation, and hot summer air temperatures are reducing stream flows and reservoir elevations, and increasing water temperatures across Idaho. These conditions have forced Fish and Game staff to modify normal operations in order to save fish and meet program goals.
The most recent example involves sockeye salmon. In late June, Fish and Game determined that a passage emergency exists for Snake River sockeye. This resulted in a decision to haul trapped sockeye from Lower Granite Dam to Eagle Fish Hatchery, which is home to Fish and Game’s captive rearing program for the species. Transporting trapped sockeye salmon from Lower Granite Dam to Eagle Fish Hatchery will begin July 6.
Under normal circumstances, these fish would complete an incredible, 900-mile journey from the Pacific Ocean to the Sawtooth Basin at the Sawtooth Hatchery near Stanley — a journey that is valuable to Idaho’s sockeye recovery efforts.
“Our preference would be to allow these fish to complete that last leg of their journey on their own, because from a genetic perspective, those sockeye that make it back to the Sawtooth Basin have a level of fitness that we want in our captive breeding program,” said Lance Hebdon, Fisheries Bureau Chief. “But based on current river conditions, hauling these fish from Lower Granite Dam to Eagle is a necessary tradeoff to increase survival this year."
Fish and Game made the decision based on increasing water temperatures throughout the Columbia and Snake River basins; low or delayed PIT tag conversion rates of Snake River Sockeye Salmon through the Columbia River; and low flows and high temperatures in the Snake and Salmon rivers above Lower Granite Dam.
The combination of high temperatures and lows flows reduces the chances of adult Snake River Sockeye Salmon successfully migrating to lakes in the Stanley Basin.
This isn't the first temperature-related issue that has affected Fish and Game's sockeye-related operations this year. The first issue occurred on April 30 when high water temperatures in the Upper Salmon River prompted the emergency early release of Sockeye Salmon smolts from Sawtooth Fish Hatchery. Observations of stressed fish and low dissolved oxygen levels in the raceways led to the decision to release the fish early in the day, before the river water warmed further.
Heat wave has also affected trout stocking, Chinook trapping
As air temperatures continue to warm, some water bodies are approaching water temperature levels that are lethal to trout. Stocking trucks are being redirected to release fish into cooler waters if necessary. It is normal practice for Fish and Game to stop stocking some waters in the heat of the summer, but in 2021 these conditions were encountered in some waters in June, which is unusual.
In the current heatwave, the South Fork Salmon River water temperatures have been approaching the mid 70s. Increasing temperatures and declining flows prompted Managers on June 22 to begin moving summer Chinook Salmon trapped for brood stock in the South Fork Salmon River to cooler water at Rapid River Fish Hatchery holding ponds. The broodstock will be held at Rapid River Fish Hatchery until they are spawned, and the eggs will be transported to the McCall Fish Hatchery for rearing to smolt.