Coho salmon spotted higher in creek this year
Coho salmon have recently been observed higher upstream in Fortuna’s Rohner Creek than in previous years, thanks in part to stream and habitat improvements completed last year.
Flow monitoring for fish passage at the 12th Street culvert has been underway and the results are being finalized according to city consultant, GHD Civil Engineer Brett Vivyan.
“California Department of Fish and Wildlife staff have conducted biological monitoring and confirmed that coho, previously only found downstream of the culvert, have been observed upstream of the culvert following the fish passage remediation project,” he said.
Approximately $2 million in grant funded stream and habitat improvements on both Rohner and Hillside Creeks, completed in 2019 and 2020 are what Vivyan is referring to.
Chris Loomis of the California Department of Fish and Wildlife said he has done research in Rohner Creek both before and after the 12th Street fish passage improvement project was completed.
“During the pre-work fish relocation conducted in 2019, several juvenile coho were found in pools below the 12th Street crossing,” Loomis said.
According to Loomis, these fish were determined to be non-natal, meaning not born in Rohner Creek, as there is no known spawning population of coho there.
“These fish were presumed to be born elsewhere in the Eel River watershed and migrated into Rohner Creek, likely seeking refuge from the Eel’s high winter flows,” Loomis said.
Loomis said he found juvenile coho salmon in Rohner Creek below the 12th Street project in January of 2020 and then from February through March 2020, found the fish both below and above the 12th Street project.
“All the juveniles we have observed have been approximately one year old and have only been observed in winter and spring months, which also supports the hypothesis that these fish are expressing a non-natal life history,” Loomis said. “If a spawning population existed in Rohner Creek, we would expect to find multiple age classes of coho throughout the year.”
Loomis said his findings underscore that a wide diversity of habitats exists throughout the Eel River watershed from the headwaters of creeks to the ocean and even streams such as Rohner Creek, with little or no spawning habitat, are important to salmon.