A rare, wild, adult steelhead estimated at 20 inches in length hides under a bedrock ledge where cool groundwater enters the lower Sisquoc River and allows over-summering survival. Shaw Allen photo.

The objective of this study was to document the presence of steelhead trout (Oncorhynchus mykiss) in the Sisquoc River watershed with particular emphasis on documentation of any large, sea-run, adult steelhead that may have remained in the watershed following connectivity between the Santa Maria River and the ocean during the high winter flows of 2004/2005. Conducting snorkeling surveys for adult steelhead that may have elected to over-summer or were trapped in the watershed provided an important opportunity to document anadromy in the system and also to assess the population dynamics of juveniles in variable surface flow reaches of the watershed. In addition, a significant downstream partial steelhead migration barrier under the Garey Bridge near Sisquoc was recently removed improving upstream steelhead migration conditions.

Six different sections of the Sisquoc River watershed were surveyed for a total of 42,005 feet of stream. All six sections surveyed contained O. mykiss for a total of 841 trout observed. The average density for the South Fork Sisquoc River, Davy Brown Creek, upper Sisquoc River, and Manzana Creek were all higher than the watershed average. The density for the lower Sisquoc River and Rattlesnake Creek were both lower than the watershed average. The lower Sisquoc River contained the largest steelhead, estimated at 20 inches in length, with Manzana Creek a close second with steelhead to 19 inches and the greatest number of steelhead over 15 inches. The upper Sisquoc River contained steelhead up to 15 inches and the South Fork Sisquoc River, Davy Brown Creek, and Rattlesnake Creek contained smaller fish up to 12, 11, and 7 inches respectively. The watershed’s overall age class distribution was well respected with 441 YOY or 0+ age class (52%), 200 1+ age class (24%), 142 age class 2+ (17%), and 58 3+ age class (7%). This survey confirms the existence of adult steelhead in the Santa Maria/Sisquoc watershed following high flow years and the importance of this watershed to regional steelhead recovery.

Matt Stoecker prepares an underwater video camera for “capturing” Sisquoc River steelhead the non-invasive way.	A healthy Sisquoc River steelhead hides in a deep pool on Manzana Creek.
High densities of juvenile steelhead in the headwaters of the Sisquoc River await their opportunity to be become steelhead.	A refreshed Doug Stoecker emerges from a successful trout count on the upper Sisquoc River.