Food habits and related studies of flathead catfish.

Abstract

The ecological role of the flathead catfish, Pylodictis olivaris (Rafinesque), in large reservoirs has not been completely understood. During the time period of April, 1975, through November, 1975, 200 flathead catfish were collected from Milford Reservoir in North-Central Kansas. One hundred and seventy-two of these fish were used in a food study. Stomach contents were analyzed by month for each length group (100 mm length groups) of flathead catfish and also were analyzed separately for each age group (year class). Frequency of occurrence and numerical analysis were used as methods for analysis. Volumetric analysis of stomach contents was also performed. Flathead catfish between 201 mm in length and 500 mm in length were found to rely heavily on benthic macroinvertebrates and fishes as forage. Flathead catfish over 500 mm in length were almost exclusively piscivorous, utilizing gizzard shad (Dorosoma cepedianum) as their most important food item. After age VI flathead catfish did not feed on benthic macroinvertebrates. As age determination was necessary, an age and growth study was also performed. Length-weight relationships, coefficients of condition and growth data were computed separately for male flathead catfish, female flathead catfish and all flathead catfish collected. A body length-pectoral spine relationship was derived using measurements from 199 flathead catfish. The value of the y-intercept from the body length-pectoral spine relationship was then used in a formula to back-calculate total length of the fish at each annuli.