Testing the effectiveness of the standard fish trap: Data from 18 days showing fish species, length, and damage in the standard fish trap and in the catch chamber in Koblenz

An objective comparison of fishway performances is virtually impossible without standardised evaluation methods and equipment. One of the devices most often applied in multispecies fishway evaluation is the box trap, which is site-specifically designed and almost always deployed without testing its effectiveness even though gear bias is common in all passive fish trapping devices. Based on a literature review and extensive expert interviews, we have compiled a set of design criteria, designed and built a box trap and evaluated both its effectiveness and possible causes of fish injuries in the fish pass at the Moselle river in Koblenz, Germany. Survey period: 2018–2023, four times in spring and twice in summer and autumn.