The 2021 smolt trapping season has begun

The fyke net trap on Redwood Creek where coho smolts are captured for biometric and population data.

NPS

April 2021 - With the onset of spring, the San Francisco Bay Area Inventory and Monitoring Network (SFAN) fisheries crew has moved to a new form of monitoring: smolt trapping. Smolt traps have been constructed at the downstream end of both Olema and Redwood Creeks to document the abundance of juvenile coho salmon migrating to the ocean. Smoltification is the physiological process where salmonids adapt from living in freshwater to saltwater. A percentage of coho smolts captured in each trap are measured, weighed, and have a Passive Integrated Transponder, or PIT tag, placed inside them via incision. Data gathered from the traps can help to estimate ocean survival and productivity and assess rates of survival through the winter season. PIT tags are activated when passing over a special antenna providing the time and identification of the fish. These data are useful for understanding the movement of fish.

Traps are checked daily and will likely run until the beginning of June. Adjustments will be made continuously to compensate for changes in weather and flow. Only a few coho smolts have been captured so far, but several adult and smolt steelhead have been trapped and released over the last week.

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