Pine Gulch Creek
Pine Gulch Creek drains a 19.4 square kilometer (7.5 square mile) watershed in coastal Marin County, California, and is the primary freshwater input to Bolinas Lagoon (Figure 1). Pine Gulch Creek is located within the CCCESU where coho salmon and steelhead occur. The watershed supports a population of steelhead and it is generally accepted that it supported a native self-sustaining population of coho salmon into the 1970s. It is likely the drought of the late 1970s coupled with in-stream damming during the same period severely depleted multiple cohorts and led to unsuitable conditions for continued survival of the species within the Pine Gulch watershed. In 2001, the National Park Service documented the return of coho salmon to the watershed beginning with the recovery of a coho carcass, and subsequent documentation of coho juveniles in the watershed the following summer (Brown and Ketcham 2002). Based on genetic tests, the coho which have returned to Pine Gulch Creek are likely strays from Redwood Creek, demonstrating a natural expansion of the genetically distinct Redwood Creek stock into a nearby watershed in Point Reyes National Seashore (Garza and Gilbert-Horvath 2003). Currently, coho salmon in Pine Gulch are considered functionally extirpated with the last coho smolt documented during the spring of 2010.
The National Park Service San Francisco Bay Area Network Inventory and Monitoring Program and California Department of Fish and Wildlife have supported monitoring of multiple coho salmon life stages in coastal Marin County watersheds since 1998. Monitoring includes:
adult escapement surveys
, which document the number of adult salmonids that successfully "escape" ocean fisheries and return to their natal streams to spawn, as well as the number of redds (gravel nests where salmonids lay their eggs) created; and
outmigrant smolt trapping
, where the number of smolts (at least year-old juvenile salmonids that have undergone changes to cope with a marine environment) are captured, measured and counted as they make their way toward the ocean; and
basinwide juvenile coho surveys
and summer index reach monitoring
which seek to quantify the number of juvenile salmonids present in the watersheds during the summer months.
Coho salmon redd numbers in the Pine Gulch Creek watershed by cohort winter 2000-2001 through winter 2011-2012.