The 100‐Watt Method: A Protocol for Backpack Electrofishing in Small Streams

Abstract

We present a 100‐Watt protocol for backpack electrofishing to capture salmonids in small streams. The protocol requires that electrofisher settings produce ~100 W of average power output. Since 2000, the protocol has been used in Idaho streams ranging in ambient conductivity from ~20–1,000 µS/cm and water temperatures from ~0–28°C, and results in satisfactory capture efficiency and desired fish response (i.e., taxis and immobilization) for pulse frequencies ranging from 30–60 Hz. Moreover, resulting spinal injuries are low (<5%) and similar between 30 and 60 Hz, contradicting past studies that show higher injury rates for salmonids at higher pulse frequencies. Despite significant variation in pulse frequency, fish size, and water conductivity, the 100‐W target works for salmonids in small streams because fish are especially vulnerable to electrofishing in small water volumes where boundary effects concentrate the electric field. Avenues of further research are highlighted that would more fully evaluate the 100‐W method.