Smolt Trapping Program Summary – Olema Creek, Pine Gulch, and Redwood Creek, Marin County, CA. 2006.

Reichmuth, Michael; Del Real, Casey; Ketcham, Brannon

Summary of results from the spring 2006 monitoring season of smolt trapping conducted on the following monitored watersheds: Olema Creek, Pine Gulch Creek, and Redwood Creek. Smolt trapping is conducted toobtain an estimate of total coho smolt production. Includes tables and figures. The National Park Service has conducted multiple life stage monitoring of coho salmon in coastal Marin watersheds since 1998. Performed in conjunction with winter spawner surveys and summer juvenile surveys, the spring outmigrant surveys permit an evaluation of abundance and survival associated with the freshwater portion of their life-cycle. At the time they smolt, most coho have spent more than 14 months in the watershed, while steelhead can be 1-4 years old. Smolt production, therefore, is the best aggregate measure of watershed condition and productivity. When evaluated as part of a comprehensive monitoring program, the smolt trap information can be compared with adult spawner indices to describe potential ocean productivity and survival, and with summer juvenile population estimates to assess rates of survival through the winter season. Smolt trapping is conducted to obtain an estimate of total coho smolt production from three of the monitored watersheds: Olema Creek, Pine Gulch Creek, and Redwood Creek. The spring 2006 monitoring season was punctuated by late spring rains (3.5 inches at Bear Valley Headquarters between April 11-12) and high flow, which delayed trap installation until Julian week 16 (April 16-22). Conditions remained relatively dry and warm through mid May, when the peak for outmigration was observed during Julian weeks 19 and 20 (May 7-20, 2006). This period correlated with cooler weather and some light rainfall. Redwood Creek estimates totaled 3,253 (±542). Capture efficiency ranged from 30% to 70%. In Olema Creek, capture efficiency ranged from 5% to 20%, resulting in a total coho smolt estimate of 10,544 (±8,399 s.d.). In Pine Gulch Creek, estimated capture efficiency ranged from 25% to 50% resulting in a total coho smolt estimate of 368 (±76 s.d.). A summary of egg to smolt survival for this reported year class indicates moderate conditions to support survival of coho in Olema (4.2%) and Pine Gulch Creek (5.6%), with Redwood Creek having the least rate of egg to smolt survival (1.5%). Development of these broader scale indices for survival in the watershed is key to effective habitat protection and management.

Smolt Trapping Program Summary – Olema Creek, Pine Gulch, and Redwood Creek, Marin County, CA. 2006.

Collections