Photo: Stuart Allen's Lake Berryessa Line

The Putah-Cache Bioregion Project:

Salmon in Putah Creek!

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On New Year's Day, 1998, three fall-run chinook salmon were seen spawning in Putah Creek. This was their first recorded appearence since Monticello Dam was built across Putah Creek some 40 years ago. Later in the year, two more appeared.

In March of 1998 UC Davis students sampled the creek, looking for juvenile salmon. Here are the results, as informally reported by Dr. Peter Moyle:

31 March 1998

We finally have concrete evidence that chinook salmon not only spawn in Putah Creek, but they do so successfully! Grad student Michael Marchetti and his trusty band of undergraduate assistants (Ryon Kurth, Heather Logan, Tom Skiles, Lisa Konyecsni) have found juvenile salmon to be common in the creek. Rain, cold temperatures, and high flows made sampling difficult and confined it to shallow margin habitats. Nevertheless, the crew found salmon at three sites: below Stevenson Road Bridge, below Pedrick Road Bridge, and below Mace Blvd Bridge. The first two sites were sampled last Thursday (March 26). Only eight salmon were collected at the time, but they were the right size (2-3 inches long) to have been the result of spawning in the creek. The fish were bright and healthy-looking. On Tuesday (March 31), 37 fish of similar size were found at Mace Boulevard in only a few hauls of the net. It is worth noting that these fish are the same size as juvenile salmon now present elsewhere in Central Valley streams, such as the Tuolumne River.

As you may recall, last December and January, large salmon were observed spawning in the reach below Stevenson Bridge, in the gravels that had been exposed by the high flows of the previous winter. The juvenile fish found in the creek could easily have resulted from the spawning of these fish. This is the first time we have really confirmed successful spawning in the creek.

We collected juvenile salmon in lower Putah Creek in 1995 and 1997 as well, but I had been reluctant to use this as definite evidence of spawning in the creek because of the lack of observations of adult fish. It is possible that the juvenile salmon present in the creek today are the offspring of salmon that were spawned in the creek three years ago (1995); many chinook salmon return to spawn at three years of age.

These small fish are significant for several reasons. First, they provide solid evidence that chinook salmon can spawn and rear in Putah Creek. Putah Creek appears to be good habitat for the juveniles because they are growing rapidly. Second, they show that Putah Creek and other small tributaries may have a role to play in the restoration of Central California salmon populations. Fall run chinook salmon in the Central Valley have recently been proposed for threatened species status by the National Marine Fisheries Service, so even small runs in places like Putah Creek may be important in the recovery efforts. Third, the juvenile salmon validate the predictions made during the 1996 Putah Creek water trial that given sufficient flows at the right time of year, salmon would spawn in the creek. Nature essentially performed an experiment for us, by providing more water than the dams could hold, allowing the creek to flow naturally in the past few years. The salmon - and other native fishes- have responded positively to the more natural flows.

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