By Will Houston
An adult Chinook salmon showing sign of infection and blindness with milky white eyes found during an Oct. 20 survey on small pools on the Eel River near Fernbridge. The lack of adequate flows on the river has caused hundreds of salmon to crowd together in small pools, thus increasing risk of infection and lack of oxygen.
Recent high tides and brief mid-September rains gave some Eel River salmon a fleeting chance to move closer to their spawning grounds. But a lack of adequate flows on the river is causing many fish to fall ill as they crowd within small pools for weeks at a time, according to a recent survey by the Eel River Recovery Project.
In an email to the Times-Standard, Wiyot Tribe Natural Resources Director Stephen Kullmann said the low-flow conditions on the Eel River are exposing these salmon to disease, predation, and poor quality water as they await adequate flows to move upriver.
“Agencies need to emphasize restoration projects in the estuary to ensure quality holding habitat,” he wrote. “Furthermore, water diversions of all types urgently need to be addressed to return Eel River flows to natural levels.”
Eel River Recovery Project board member and local kayak guide Eric Stockwell had surveyed these small pools near Fernbridge earlier last week where he saw about 200 fish harboring in an algae-filled pool that was only four feet deep — almost four times shallower than their normal cold-pool refuges.
Stockwell noticed about 25 percent of these fish had clouded eyes and were exhibiting the odd behavior of not swimming away as he moved closer to them
“Several fish were blind,” Stockwell said recounting the experience.
The exact cause of this blindness is currently unknown, but Stockwell said the biologists he contacted ruled out the gill parasite ich, which had sparked recent concerns of Klamath River salmon.
With more high tides and a flush of rain expected throughout the week, fish still holding in the estuary may read the resulting higher flows as a signal to move upriver. But Stockwell said these fish will be taking a risk if the drought conditions continue.
“If it doesn’t rain significantly in the next few weeks, all these fish are going to fall victim to these pathogens and diseases,” he said.
Stockwell estimates there are about 1,000 fish holding on the Eel River between Fernbridge and Fortuna. Recent annual Chinook salmon runs range from about 20,000 to 50,000 fish, Stockwell said, with the majority of this year’s run still in the ocean.
One of the main concerns for the fish in these shallow, crowded pools is the amount of available oxygen in the water, according to a Eel River Recovery Project news release on Tuesday. Eel River Recovery Project said one factor that “cannot be ruled out” for this issue is algae.
While providing dissolved oxygen to the water through photosynthesis during the day, the algae also uses oxygen at night while it respires, thus reducing the overall oxygen for the neighboring salmon. And without any significant flows to flush the algae away, the algae accumulates on the pool bottoms, according to the project.
“The number of large fish pushing into these pools with high tides could exacerbate the problem,” the project’s news release states.
The project has borrowed a dissolved oxygen meter and plans to monitor the pools to check for any possibility of lethal oxygen levels, according to the news release.
Along the shallow stretches of the Eel River are deeper, cooler pools such as those near Rio Dell and Fortuna that the fish can hold in while waiting for the next large rain flush. While some of the salmon have made it to these pools, others decided to stay in their smaller pools to wait out the dry period.
“It’s like little lakes with creeks between them,” Stockwell said. “… There are these areas of refugia where the fish might have a better time. But they don’t know that.”
According to the Eel River Recovery Project news release, the fish need the river to flow at a minimum of 100 cubic feet per second to swim up the shallow riffles. The drizzle of rain that hit the North Coast last night and forecast for today will cause a rise in the river, but will only reach at maximum of about 80 cubic feet per second, according to the California Nevada River Forecast Center.
Despite the drought and other impacts on the Eel River, Stockwell said the waters are flowing high enough that fish would have the physical ability push their way up the shallow areas of the river.
“But they know that if the push their luck they’re more likely to get predated on,” he said.
While this week’s rain is only supposed to measure up to a half-inch or less, National Weather Service meteorologist Shawn Palmquist in Eureka said the approaching system on Sunday will be a better sign for the fish.
“It looks like a colder and wetter system is going to move in on Sunday,” he said.
But the fish won’t be patient forever and the urge to spawn will outweigh the dangers, Stockwell said.
“Whether it rains or not, the fish will push,” he said. “They’ve even beached themselves.”
If the fish are unable to reach their spawning grounds, the run will return in fewer numbers in the following years and could disappear entirely over time as had occurred with the now non-existent spring-run Chinook salmon on the Eel River.
“Here your early fall run might fall victim to that same kind of situation,” Stockwell said.
Article originally published by Eureka Times Standard. Click here to read original.