An opening-closing, single-sample net system designed to capture micronektonic organisms is described. The net is opened and closed at the mouth by mechanical time-release devices, and can be hauled from small ships on hydrographic wire. Data are presented from a series of 4 hauls made with this system during a study of sonic scattering layers. The population maxima of euphausiids, sergestid prawns and physonect siphonophores corresponded to the level of the main scattering layer. Fishes were concentrated below the layer, and amphipods above it.