Two hundred juvenile coho were plucked from Redwood Creek on Wednesday morning, to be reared in captivity in an effort to prevent their extirpation from the creek. Despite restoration projects that began in 2009 to create more floodplain and fish habitat there, annual numbers of adult coho in the waterway have fallen into single digits in the last few years, according to the California Department of Fish and Wildlife, which is collaborating on the rearing effort along with agencies like the National Marine Fisheries Service, the Golden Gate National Recreation Area and the Army Corps of Engineers. Such low numbers can make it extremely difficult, if not impossible, for the coho to recover without help. Based on historical populations in the creek, which flows down Mount Tamalpais and empties into the ocean at Muir Beach, the National Oceanic and Atmospheric Administration set a target for 272 adults. The plan is to take the juveniles from the creek for the next three summers (cohos breed in three-year cycles) and raise them at Warm Springs National Fish Hatchery, in Geyserville, then release them back into the creek as adults, when they will hopefully spawn in the wild. According to the Department of Fish and Wildlife, captive rearing is a “last resort” to prevent extirpation because of the “potential ecological and genetic risks,” and said the decline in Redwood Creek over the past decade, along with drought conditions, necessitated immediate intervention.