Diel Activity Levels of Centrarchid Fishes in a Small Ohio Lake

Abstract

We used three different sizes of trap nets (small, medium, and large sizes of both mesh and throats) sampled at 6-h intervals to determine peak activity time(s) for fish along the deep vegetation line in Sandy Lake, Portage County, Ohio. Over 90% of the total catch comprised bluegill Lepomis macrochirus, largemouth bass Micropterus salmoides, pumpkinseed L. gibbosus, and black crappie Pomoxis nigromaculatus. All four species had their lowest catch per unit effort (CPUE) at night (2200–0400 hours). Different length-classes of pumpkinseeds and black crappies had peak CPUE during different times of the day. Smaller length-classes of all species (i.e., those captured in small and medium trap nets) had peak CPUE during either dawn (0400–1000 hours) or midday (1000–1600 hours), whereas the only piscivores captured in high abundance (black crappies 150–303 mm total length captured in large trap nets) had higher CPUE at dusk (1600–2200 hours) than during any other time of the day. It is possible that these activity patterns are affected by predation risk or food availability. These findings indicate that individual species or length-classes do not typically interact directly even though they use the same habitat. Therefore, when predicting potential species interactions in natural systems, it is important to consider diel changes in behavior. When possible, sampling schedules should take into account the activity patterns of the species of interest to ensure that information is obtained from the most appropriate time(s) of day to more accurately assess species interactions.