Effects of Color, Mesh Size, Fishing in Seasonal Concentrations, and Baiting on Catch Rates of Fishes in Gill Nets

Abstract

Increasing efficiency of gear to catch more fish per unit of effort and to catch species and sizes selectively are inherent objectives in fishery research, population control, and commercial fishing. Color and mesh sizes of gill nets, fishing in seasonal concentrations of fishes, and baiting gill nets were tested to identify single and combined factors which enhance efficiency of nets for a variety of objectives in Elephant Butte Lake, New Mexico. Catch rates of one to five species of game, forage, and commercial fishes were significantly different (P < 0.10) in nets of any of nine colors than they were in white nets. Seasonal differences occurred between multifilament and monofilament nets. Stretch-meshes ranging from 5.1 to 15.2 cm were selective for all species and the three groups of fishes. Selectivity changed linearly in 10.2-, 12.7-, and 15.2-cm meshes; catches of commercial fish increased and those of game and forage fishes decreased with increasing mesh size. Concentrations of several species changed seasonally between upstream, middle, and downstream thirds of the lake. Catch rates of commercial fishes in certain areas were three times those in other areas during certain seasons and averaged about twice as high during a year. Eighteen organic substances were tested as bait to attract fishes to the vicinity of gill nets. Most baits attracted several species, repelled several, or both. Investigations of selective harvest of river carpsucker and of all commercial fishes revealed that combinations of brown nets − 10.2-, 12.7-, and 15.2-cm stretch-meshes—and fishing in seasonal concentrations of carpsucker and smallmouth buffalo resulted in catch compositions of 80 to 85% commercial fish. Tested and potential combinations of color, mesh size, fishing in seasonal concentrations, and baits are discussed to show effects on selectivity and efficiency of gill nets and to demonstrate use of results for designing netting schemes to achieve various objectives.