Aspects of the Life History of the Stippled Darter Etheostoma punctulatum

Abstract

Aspects of the life history of the stippled darter Etheostoma punctulatum were studied in the Spring River in SW Missouri. Females attained a maximum standard length of 85 mm and males 83 mm. Both sexes lived slightly more than 4 years. Sparvning began in early February and continued through late May. Males were mature at 1 year of age while only those yearling females at least 49 mm long produced mature ova. Females contained an average of 447 ova2-0.55 mm in diam in two distinct size modes and a group of smaller developing ova. The presence of these distinct size groups of ova throughout the spawning period indicates that two or more clutches of eggs were produced by each mature female. The fertilized eggs were 1.6 mm in diam and hatched in 11 days at 16 C. The diet was made up primarily of crustaceans and aquatic insect larvae. INTRODUCTION The stippled darter Etheostoma punctulatum is a robust darter and the largest in the subgenus Ozarka, reaching 88 mm SL (Kuehne and Barbour, 1983). This darter is distributed throughout the Ozarks where it is most often found in small creeks and spring branches having clear water with permanent flow and silt-free bottoms. Pflieger (1975) indicates it may be found in quiet pools and backwaters where it hides around large rocks or in beds of organic debris. Although not uncommon within its known range of distribution, there are very few populations large enough to permit taking the numbers necessary for life history analysis. Fishes restricted to small headwater streams are frequently subjected to wide fluctuations in environmental conditions. This study was begun with samples being taken in two streams but was terminated in Weaubleau Creek in Hickory Co., Missouri, when dry weather reduced the stream to a few isolated pools and destroyed the darter population. The danger faced by darter populations in headwater locations is also increased by human activity. The second stream location is immediately downstream from a troutrearing facility through which nearly all water in the stream passes. Cleaning of the trout pools in February 1983 produced silt which covered the gravel bottom of the sampling area to a depth of 0.5 m in many places. This site is also 2-km upstream from a well-publicized source of dioxin contamination in the watershed and fishes in the area are known to be concentrating this substance. Activities affecting this stream section may eliminate the desirable habitat which sustains populations of Etheostoma cragini, E. microperca and E. punctulatum among others. Important contributions on life history and ecology of other members of the subgenus Ozarka have been made, but a basic study of the stippled darter has been lacking. Life history features of the threatened paleback darter Etheostoma pallididorsum were determined from preserved museum specimens by Hambrick and Robison (1979). Taber et al. (1986) discussed several aspects of the life history of E. cragini; Boschung (1979) commented on the life history and distribution of E. boschungi, and Etnier (1970) made significant contributions to the known distribution of E. trisella. More recently Ryon (1986) studied the life history and ecology of E. trisella. Information gained by studying the stippled darter is important to the information base which could be used in conservation of this and other less abundant species of its subgenus.