Effects of lunar cycles on the activity patterns and depth use of a temperate sport fish, the largemouth bass, Micropterus salmoides

The behaviour of free-swimming, telemetered, adult largemouth bass, Micropterus salmoides (L.), was monitored using a whole lake, three-dimensional acoustic telemetry array to test the hypothesis that fish activity and depth distribution are influenced by lunar phase. The percent of lunar face shining and whether the moon was waxing or waning were significant determinants of swimming activity and depth distribution during most of the lunar cycles evaluated, although these patterns were not consistent across the year. In spring and summer, daily depth distribution followed a pattern in which the fish inhabited greater depths on the 26-50% and 51-75% waxing moon. Fish daily movement distances were five times greater during spring and summer than in winter, but no repeatable patterns were noted in relation to lunar periodicity. This research suggests that solunar tables frequently consulted by recreational anglers may have little predictive value for identifying peak fishing time.