Publication Date

8-1974

Advisor(s) - Committee Chair

Robert Hoyt, Gary Dillard, Rudolph Prins

Degree Program

Department of Biology

Degree Type

Master of Science

Abstract

Various aspects of the biology of the southern redbelly dace, Chrosomus erythrogaster Rafinesgue, were intensively studied on a population in Ivy Creek, Warren County, Kentucky from 1971 to 1972. Reproduction in the southern redbellv dace occurred from May through June. Older, sexually mature individuals spawned early in the reproductive period while those in their first year of life spawned during late June. The number of eggs shed annually ranged from 140 to 681 with an average of 385. A positive correlation existed between the number of eggs shed and standard length.

Differences between the sexes of the species were marked and included intensity and distribution of pigmentation, breeding tubercle development and length and shape of the pectoral fins. Males were most distinctive, having prominent scarlet ventral surfaces and breeding tubercles on the head and fins during the reproductive period. Males had more distinctive coloration as well as longer and broader pectoral fins. While more females than males were collected during this study, no significant deviation from the theoretical 1:1 sex ratio was observed.

The normal life span of the southern redbelly dace was about two years with a few individuals living into the autumn of their third year (26-30 months). Males disappeared from the populations slightly earlier than females. Age Group 0, or individuals in their first year, constituted the dominant age group.

Growth in length was greatest during the first year of life while growth in weight was greatest during the second year and that portion of the third year survived. No statistically significant deviation was observed between the theoretical cubic response of growth in weight to length and that observed among the specimens in Ivy Creek.

Coefficient of Condition values were greater for males than females when gonad weight was excluded. Converse results were observed when the gonads of both sexes were included in the condition determinations. Seasonally, condition coefficients for both sexes combined were greatest during the spawning season, lower during the warm-water months and lowest during the cold-water months.

Food habits were generally non-specific with combinations of algal forms, (filamentous chlorophytes and diatoms) and organic detritus constituting the major dietary components. Aquatic insects were commonly found in the guts of larger specimens.

Southern redbelly dace existed as a part of a larger assemblage of fish species and because of their food habits and reproductive behavior co-existed successfully. Parasitism of the species was not obvious.

Disciplines

Biology | Life Sciences

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