Evaluation of sampling gears for fish population assessment in Alaskan lakes

Abstract

Three lakes in Alaska's Interior and Kenai Peninsula were sampled during summers, 1982 and 1983, to evaluate sampling gears used for fish population assessment in Alaskan lakes. Two active gears (electrofishing boat and seines) and two passive gears (fyke nets and minnow trap) were evaluated for performance in catching power, size selectivity, species detection, fish destruction, manpower requirement, cost, portability, and field repairability. Three different electrofishing boat currents (AC, DC, and pulsed-DC) were also evaluated. The electro fishing boat had highest catching power, while fyke nets and minnow trap had highest catch per man-hour of labor. Seines had variable catching power, dependent upon shoreline substrate and sites to haul the seine to shore. Night electrofishing had higher catching power than day electrofishing when fished in a clear water lake, as opposed to equal catching power in a brown water lake. All three electrofishing currents exhibited a consistent pattern of length selectivity for coho salmon (Oncorhynchus kisutch). Planning of fish population assessment projects involves (1) clearly stated objectives, (2) knowledge of project constraints, physical or economic, and (3) knowledge of the sampling attributes of gears to be used.