Abstract: This invention obtains samples of fish life in the larvae and egg stage and shortly thereafter, plankton and similar marine life. By taking samples before and after water has passed through cooling facilities of electric generating plants along a river, some of the effects of the power plant on the environment can be determined. The outstanding feature of this invention is that it collects the samples without passing the marine life through pumps in which much of it is killed or injured. Samples are collected in partially submerged equipment into which the water flows by gravity, and the water is discharged by pumps after the samples have been removed.