Trout Hatchlings Spotted

Hundreds of young trout hatched last week in Stonybrook Creek in the Alameda Creek watershed, possibly the offspring of a historic pair of steelhead trout.

A steelhead pair dubbed “Bonnie and Clyde” were given a helping hand upstream in late February past barriers in lower Alameda Creek and radio tagged to monitor their movements. They swam together up Niles Canyon to Stonybrook Creek, where they were exhibiting spawning behavior in early March. On Monday hundreds of trout fry were observed in the creek reach where the steelhead pair likely spawned and are still holding.

“If the young trout are confirmed to be offspring of steelhead rather than resident rainbow trout, this will mark the first natural reproduction of steelhead trout in the Alameda Creek watershed since the mid-1960s,” said Jeff Miller, Director of the Alameda Creek Alliance. “Restoration projects underway could allow steelhead and salmon to swim freely to spawning areas in Alameda Creek within a few years.”

Trout eggs typically hatch within 30 to 45 days into what are known as alevins, tiny fragile fish that live off their attached yolk sacks. About 4 weeks later the young trout (known as fry) emerge from the gravels where they were spawned and begin to feed.

In 1999, a female steelhead named “Stella” was rescued at the BART weir and later swam into Stonybrook Creek, where she possibly spawned with resident rainbow trout. Stonybrook Creek has almost two miles of suitable habitat for spawning and rearing of trout and steelhead, but several road crossing culverts create migration problems in the lower creek. CalTrans has committed to replace a culvert at the bottom of Stonybrook Creek with a free span bridge.