The salmon population has continued to decline in the Sacramento River because of depleting water levels and increasing temperatures. This is after nearly 95 percent of the Winter Run Chinook salmon died in 2014 due to the drought.

“This year they’re estimating that 25 percent less fish than last year have passed,” said Jason Roberts, senior environmental science major and supervisor for the California Department of Fish and Wildlife. “Survival is lower for the entire population than it was last year.”

Over the summer, the goal was to keep the water at 57 degrees instead of 56 and not exceed 58 degrees, Roberts said. The water did spike above 58 degrees for a few days but other than that, the water temperature was consistent.

“Everyone assumed that survival would be higher than it was last year,” Roberts said. “It turned out not to be, and people are starting to look into the reasons why survival was lower.”

The Federal Fish and Wildlife Service has a hatchery specifically for Winter Run Chinook salmon to ensure their survival, he added.

Since the salmon population continues to decline, the California Department of Fish and Wildlife is beginning to investigate why the population failed to increase.

“All of the science suggested that this year’s water management strategy would have a higher survival than last year,” Roberts said. “I think they’re just starting to dig into the data and trying to find answers.”

Austin Herbaugh can be reached at [email protected] or @aherbaugh14 on Twitter.