Klamath River Update – March 2024

On March 2, CDFW reported the mortality of recently released (Feb. 28) salmon fry from the new Fall Creek Salmon Hatchery located on a Klamath River tributary upstream of the site of the recently removed Iron Gate Dam. The Iron Gate Hatchery located at the foot of the dam site was removed with the dam and replaced by the Fall Creek Hatchery. Mortality of the salmon fry was attributed to gas bubble disease caused by the fry passing through the Iron Gate Dam release tunnel.

Iron Gate Reservoir and the three upstream reservoirs were emptied beginning on January 11 prior to dam removal. As the reservoirs were drained, the gage below Copco Dam picked up a large increase in turbidity with an associated complete loss of dissolved oxygen (Figure 1). Oxygen returned to the water after several days despite continued high turbidity. This indicated the initial dissolved oxygen loss was likely related to the flush of organic sediment from the bottom of the reservoirs as the draining neared completion. After the flows stabilized (Figure 2) and water level in the river had dropped six feet by the end of January, turbidity dropped and stabilized near 3000 mg/l suspended sediment, and normal high dissolved oxygen returned. Turbidity was measured using three parameters (Figure 3).

The hatchery salmon fry released on February 28 were subjected to a Klamath River with elevated turbidity (suspended sediment concentrations above 2000 mg/l). Such concentrations for extended exposure (days) are highly detrimental to salmon fry.1 The combination of high suspended sediment and gas bubble disease likely has contributed to poor juvenile salmon production this year in the lower Klamath River.

The removal of the Klamath River dams will have substantial long-term benefits for salmonids. As the dam removal process proceeds, it is important to mitigate the short-term impacts of high turbidity levels to the degree possible. Continuing high turbidity events (see March levels in Figure 3) do not bode well for hatchery or wild salmon in the Klamath this year. With nearly 4 million juvenile Chinook salmon yet to be released from the Fall Creek Hatchery this year, it would be wise to either wait for next fall to release them or truck the smolts to the Klamath estuary.

Figure 1. Water level, suspended sediment, and dissolved oxygen in the Klamath River above Iron Gate Reservoir and mouth of Fall Creek, January 16 to March 10, 2024.

Figure 2. Streamflow below the Iron Gate Dam site January 1 to March 10, 2024. Source: USGS.

Figure 3. Suspended sediment and turbidity upstream of Iron Gate Reservoir above the mouth of Fall Creek near Copco, January 16 to March 10, 2024.

  1. Newcombe, C.P., and J.O.T. Jensen. 1996. Channel suspended sediment and fisheries: a synthesis for quantitative assessment of risk and impact. North American Journal of Fisheries Management. 16:693-727.

2024 Salmon Season in Doubt

On March 1, 2024, the California Department of Fish and Wildlife (CDFW) held its CDFW Annual Salmon Information Meeting via a webinar. The prognosis for a 2024 salmon season does not look good.

The closure of all California salmon fishing in 2023 brought an uptick in salmon escapement to 133,000 in the Sacramento River, which is somewhat positive. The forecast for this year’s fishable stock in the ocean (made up of broodyears 2021-2023), however, is not much better than last year’s, with the lingering effects of the 2020-2022 drought. If a normal fishery had been held last year or were to be held this year, the salmon stocks would no doubt fall into an “over-fished” status.

Notable points of interest:

  • Without fishing in 2023, there was an uptick in the relative percentage of four-year-old spawners, especially in the Klamath system. This was likely related to the fishery closure and strong production from broodyear 2019.
  • There seemed to be significant concern that a higher fishable stock level was important for the good of the endangered southern Orca population that feeds primarily on Chinook salmon.
  • The fisheries agencies appear more comfortable with a fishable stock well over 180,000 than with the forecasted 213,000 for 2024. Note that the 2024 forecast was based on jacks from broodyear 2021 that returned in 2023 that were produced in the heart of drought years 2021 and 2022. Jack numbers are representative of age three adult return numbers the following year (2024).
  • Not a word of concern was expressed for protecting wild, natural-born returning salmon.
  • There was no mention of prescribing a mark-selective fishery despite the recent adoption of such a measure for Columbia River Chinook salmon and its universal use in Coho salmon and steelhead fisheries.

Nothing was said about the possibility of at least experimenting with mark-selective fishing, wherein harvest is allowed on fin-clipped hatchery salmon, a practice prescribed with increasing frequency in Pacific Northwest salmon fisheries. I believe the fishable stock (age 2-4) of marked salmon in the ocean in 2024 is about 300,000.1 A mark-selective fishery could harvest 200,000 of these fish without harming spawning stocks of wild or hatchery fish.2

Sport and commercial fishermen should advocate for a mark-selective fishery in 2024 rather than a second consecutive year of a closed fishery. The Pacific Fishery Management Council is setting harvest control rules for California fishing in early March.3