Record-high temperatures over the last couple of months have caused the deaths of nearly 250,000 sockeye salmon in their annual trip up the Columbia River this year. Scientists and conservationists are stunned by the unprecedented number of sockeye salmon lost to poor weather conditions, calling into effect commercial and recreational fishing restrictions in and around the Columbia River indefinitely.
AN ANNUAL STRUGGLE
Hundreds of thousands of sockeye salmon travel up the Columbia River every year around July 1, passing the Bonneville Dam on their way to their breeding grounds in Canada. Last year, over 645,000 sockeye successfully made the trip in what was the largest run since the dam’s construction in 1938.
In fact, record numbers of sockeye salmon have been passing through the dam since 2012. Scientists hoped this trend would continue in 2015, predicting the return of more than 100,000 sockeye salmon.
KILLED BY HEAT AND STRESS
However, record-breaking weather conditions earlier this month have raised water temperatures to above 72 degrees Fahrenheit—roughly five degrees above the average temperature for the Columbia River in July.
According to Mark Ahrens, manager of the Spring Creek National Fish Hatchery in the Columbia River Gorge, sockeye salmon are typically used to waters that range between 40-50 degrees. When sockeye live in waters that range from the mid 50’s into the 60s, Ahrens says the salmon get stressed very easily, as less oxygen is held in warmer waters, making it harder for them to breathe. Higher temperatures also kick their metabolisms into overdrive, burning through stores of energy that are crucial to their survival.
But that’s not all that sockeye salmon making the trip up the Columbia River have to worry about this year. According to Theresa Scott, the Washington Department of Fish and Wildlife’s coordinator, the carcasses of the dead sockeyes have shown signs of serious infection. According to Ahrens, this is due to an increase in microscopic killers: “Bacteria, pathogens, and viruses get more and more effective at doing their jobs when the water gets warmer, and fish less so.”
Ritchie Graves, a biologist at NOAA has recently predicted the deaths of up to 80% of this year’s sockeye salmon population passing through the Bonneville Dam.
RISK OF ENDANGERMENT
While some populations of sockeye salmon living in US waters are currently listed under the Endangered Species Act, the ones that live in the Columbia River are not, prompting new legislation to be passed for their protection.
To help aid in their conservation, Oregon and Washington officials have both agreed to place a ban on commercial and recreational fishing indefinitely. With consistent trends of increasing temperatures across the nation, many scientists such as Theresa Scott believe this to be the first of many such occurrences that we will see in the near future: “This is a wakeup call and a dress rehearsal for what fishery managers years from now will be dealing with on a regular basis.”
