The Life History of the Yoke Darter, Etheostoma Juliae


Paul W. James

Date of Graduation

Spring 1983


Master of Science in Biology



Committee Chair

Charles Taber


Aspects of the life history of the yoke darter, Etheostoma juliae Meek, were studied in the James River, Missouri. A total of 652 specimens was collected from September, 1981 through September, 1982. Yoke darters attained a maximum standard length of 71 mm and had a maximum longevity of slightly over three years. Spawning began in mid-May and continued through mid-July on swift riffles. Females typically contained clutches of 70-80 mature ova which were 1.3 mm to 1.5mm in diameter. The eggs were buried in small patches of fine gravel behind large rocks and were transparent, demersal, and adhesive. Males and females spawned at one year of age provided they had attained lengths of 30mm and 32mm, respectively. Length-weight relationships were similar for both sexes but males grew at a faster rate and attained a larger size. Diet was composed of aquatic insect larvae with chironomids being the major food source. The success of this species can be attributed in part to its ability to inhabit the swiftest part of a riffle where competition with other darters is reduced.

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© Paul W James