Publication details
Daily feeding habits of the black bullhead catfish (Ameiurus melas) under conditions of high-density population
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| Year of publication | 2023 |
| Type | Conference abstract |
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| Description | The black bullhead is species of the family Ictaluridae, native to North America. During the end of the 19th century and the beginning of the 20th century, it was intentionally introduced into Europe and in 2003 (Drozd & Blaha, 2006; Hartvich & Lusk, 2006), this time unintentionally, introduced to the Czech Republic. There are studies of the feeding biology of the species in different localities (Leunda et al., 2008) or seasons (Jaćimović et al., 2021; Ruiz-Navarro et al., 2015). Our study was aimed at feeding biology and changes in its patterns during the day in a population consisting of a high number of dwarf individuals of uniform size. We expect a high level of intraspecific competition and therefore mechanisms maximizing the individual niche separation, such as a generalistic diet or changing food composition during the day. Fish were sampled in Mlazicke tune pond, Czech Republic in August 2021 by 16 traps with artificial bait from 8 to 22 hours. Collected fish were grouped into three time periods (morning, afternoon, and evening). Traps were placed along banks and catfish were removed every hour and were immediately frozen. In the process of dissection, the percentage of each food component was visually estimated, and prey was counted. The frequency of occurrence and index of preponderance (to show the dominance of food items) were calculated (Natarajan & Jhingran, 1961). The daily feeding activity was changing during the daytime showing 3 distinctive peaks. High feeding activity was observed in the morning between 8–11, afternoon activity peaked between 13–15 and evening from 19 to 22. Unlike other studies conducted in native (Etnier & Starnes, 1993; Scott & Crossman, 1973) and non-native (Jaćimović et al., 2021; Leunda et al., 2008; Ruiz-Navarro et al., 2015) range of the black bullhead, in our study was found a high prevalence of detritus and plant material. Both components had the mean frequency of occurrence similar to chironomids, but the index of preponderance of detritus was twice higher (49.2, 14.3 and 17.3 respectively), showing the dominance of detritus over other food components. We observed a decrease in the detritus preponderance in the evening. On the other hand, preponderance of plant material and gastropods increased in the evening. Chironomids dominated in the diet over plant material for most of the time, but in the evening, plant preponderance became higher than of chironomids. Our findings suggest changes in the feeding habits of the black bullhead during the day, which might play a role in niche separation and invasion success of this species. |