Distribution of Clinostomum marginatum (Yellow Grub) Metacercaria in Smallmouth Bass Populations from Crooked Creek in North Central Arkansas

Fourhundred thirty-three smallmouthbass (Micropterus dolomieui) were collectedfrom ten sites on Crooked Creek in North Central Arkansasfrom just below the city of Harrison to the White River in the summers of 1988-90.Necropsy of thesehosts for yellowgrub {Clinostomum marginatum) metacercariae showed a range of mean abundance (average/fish) from 1.4± 1.9 (SD) at a far up stream site to 105± 368 at the White River juncture. An increasing mean abundance of C. marginatumwas seen from the uppermost sites of the creek downstream to the White River.Relatingstream mileage with mean abundance gave a correlation coefficient(r) of 0.78, withP= <0.01. Maximumabundance (maximumnumber of parasites in a single host from a site) ranged from 7 to 2500 and also showeda positive correlation with stream mileage (r = 0. 77, P= <0.01). Prevalence (°/o fish infected) at the different sites ranged from 61 to 91%but showed no significant correlation with stream distance. The increasingly heavier infections seen in the downstreamsites are not due to poor water quality but probably to the combination of the greater presence of the definitivehost, the great blue heron, and large intermediate host (smallmouth)populations.