Special to the Willits News
Posted December 31, 2013
Divers jumped into lower Eel River pools again in fall 2013 to document the size of the fall Chinook salmon run as part of the Eel River Recovery Project's (ERRP) annual monitoring program, which is co-sponsored by the Humboldt Redwood Company and the Wiyot Tribe. More than 70 divers participated in six organized dives and dozens of other volunteers are now tracking the salmon as they migrate and spawn throughout the watershed. The peak dive count was almost 6,000 Chinook salmon on November 9, but low flow conditions allowed a December 5 dive that indicates a new wave of late-run fish is entering the lower Eel River despite sparse rains.
The lower Eel River dive counts are conducted by divers forming a line and swimming together through pools holding salmon.
In 2013 the pools at Fernbridge and immediately above and below were filled in and fish were only able to hold in five pools further upstream. Counts escalated from 1,854 Chinook salmon on October 5, to 4,244 on October 23, to the highest count of 5,954 fish on Nov. 9. Team size did not allow census of the Weymouth Pool above the mouth of the Van Duzen River, which held more than 1,200 salmon in 2012. Therefore, the ERRP dive totals are not a total population estimate. Also, a number of fish migrated upstream before dives began and were
not counted and more are still coming. Fish that had dispersed with early rains began spawning around Nov. 10 and they were joined by thousands more as the rainfall of November 20 and 21 nudged Eel River flows up and allowed passage upstream.
In a normal rainfall and flow year, the river and its tributaries turn brown with sediment, but the drought of 2013 has salmon spawning in plain view, much to the delight of residents throughout the watershed. Also, ERRP was able to dive two lower Eel River pools on Dec. 5 and document a late run of Chinook with video taken by a diver using scuba gear.
There were more than 1,000 mostly fresh Chinook salmon and Coho salmon and bright adult steelhead were also counted.
Although lack of rain is preventing access to tributaries, spawning gravel quality is high in the main stem Eel River from Van Arsdale Dam in Mendocino County to Dyerville at the convergence with the South Fork. Salmon eggs usually take 30 days to hatch and then larvae or sac-fry are under the gravel for another 30 days.
Major rain and flow events could cause bed load movement and mortality, but if drought conditions prevail, then a good year class of Chinook salmon juveniles could result. Eggs will have less chance of survival in the event of high flow in watersheds where there is substantial excess sediment in transport.
An increase in flow at the Potter Valley Project on Dec.
1 triggered movement of fresh fish in the main Eel above Dos Rios and ERRP volunteers report that spawning subsequently went into full swing at Hearst east of Willits. Chinook salmon spawners were only able to reach the lowest reaches of the Middle Fork during late November rains and lack of flow in the South Fork and lower Van Duzen is preventing access to new fish. Consequently, late run fish can only get to main Eel River spawning beds so activity should continue there for another 30 days. Spawners did not pass Van Arsdale Dam until Thanksgiving week in 2013 and only 28 fish had passed by Dec. 4, which contrasts with the record 3,400 Chinook salmon that passed upstream by that date in 2012.
ERRP continues to track salmon spawning throughout the Eel River basin and video and photo document activity, including use of kayaks to access more remote reaches. To assist or report fish sightings, call Eel River Volunteer Coordinator Pat Higgins at 223-7200. This project is being made possible by grants from Patagonia and the Salmon Restoration Association of Ft Bragg. To see photos and video of salmon and to access reports, see www.eelriverrecovery.org.