Brandi Parsley of the Yakama Nation Fisheries measured juvenile salmon after electrofishing.
On a cold, dark March night, past bedtime hours, a dark, wet figure appeared on my doorstep in layers of rubber and neoprene, seeking warmth and refuge from cold waters. It was then I knew the hidden story of the night snorkelers should be shared.
You see, a peculiar thing happens in the river on certain nights here in the valley. It happens on a schedule, though infrequently and if you were to stumble upon it you might think there was some kind of covert, special operations tactical team swimming upstream on a secret mission. It’s a little-known activity, a hidden occurrence known only to those who are closely linked to the people involved, which is why I know it happens. It takes place on segments of the rivers largely hidden from any public view, out of sight, and in the dark of night.
Crawling up the riverbed in formation, dark figures dressed in dry suits and neoprene pick their way upstream gliding over rocks, battling the downstream current. With snorkels and masks, guided by underwater lights, the search for rare and endangered fish is undertaken by a squadron of clandestine scientists from the various resource agencies tasked with monitoring fish populations.
Who in their right minds would swim in the river in the winter at night? Biologists, that’s who. My husband happens to be one of these, and he recently participated in a survey by the Yakama Nation on the Chewuch River during an especially cold evening to monitor juvenile fish populations within a recent side channel restoration. I got curious.
But why night snorkeling? During the night, young fish are less reactive and come out of their safe cover where they can more easily be counted, so night snorkeling is often a preferred survey method. Monitoring programs that support the work of restoration projects play an important role in the efforts to measure the success of the various projects on salmon recovery. Data gathered from surveys inform metrics such as survival rates, rate of growth, habitat use, and species distribution.
Snorkel surveys are particularly helpful to biologists who are monitoring specific fish use of certain habitat types such as riffles and pools, and especially man-made restoration structures. Here in the Methow River and its tributaries of the Twisp and Chewuch Rivers, snorkel surveys are part of on-going monitoring the effectiveness of salmon habitat restoration efforts such as the log structures and side channel enhancements done by the various partners across tribal, local, state and federal agencies who are involved in salmon recovery.
Due to the inherent danger of hypothermia or entanglement of snorkeling at night in frigid water, strict protocols for safety are used. A bank tender who communicates with the snorkelers assures safety and makes sure people stay in their formation, recording data.
Depending on the monitoring objectives, biologists design their surveys to minimize both disturbance to the habitat and stress on fish. Another little-known activity commonly used by fisheries scientists is electrofishing. This is a more invasive technique where fish are stunned with a small electrical current and rise to the surface. Field crews quickly scoop up the fish in nets to accurately measure and count them, leading to more reliable age assessments and counts.
Electrofishing is also used to clear an area of fish for construction for things like culvert replacement or new habitat structures. Fish are gently handled and placed back in the water as quickly as possible where they will return to normal activity.
