In May darters became difficult to find, and most of 

 those caught were brought to the laboratory. Spawn- 

 ing could not be observed in the wild because of the 

 high turbidity in the creek, and all spawning observa- 

 tions were made on acjuarium fish. 



After spawning time fine-mesh screens pro\cd no 

 better than the standard minnow seine in attempts tti 

 net hatchlings. For the rest of the year the seining 

 proccdiu'e was essentially the same as that used during 

 tlie prespawning season. However, a much smaller area 

 was sampled to minimize the effects of such variables 

 as air and water temperatures, turbidity, pH. and avail- 

 able food supply. An attempt was made to obtain about 

 35 young on each visit. 



In the laboratory total and standard lengths were 

 recorded for almost all specimens and body depths for 

 adult females. Adults were sexed, aged, and examined 

 for development of color, nuptial tubercles, genital 

 papillae, and numbers of eggs. Specimens were aged 

 by counting annuli on scales removed from the left side 

 of the body above the lateral line near the junction of 

 the dorsal fins. 



A few females from each collection were dissected; 

 the color of the ovaries was noted; and egg size, number, 

 and estimated amoimt of differentiation were recorded. 

 A series from each collection was examined for stomach 

 contents, and parasites were also noted. Young were 

 studied for growth and for development of squamation 

 and the lateral-line system, and the stomachs of a few 

 were examined for food items. 



Stomachs of some large, associated species, such as 

 sunfishes, were also examined to see if they were preda- 

 tors of darters. Stomachs of equal-sized species of 

 minnows and other darters were studied for e\idciice 

 of competition for food. 



HABITAT AND ASSOCIATED SPECIES 



The microhabitat of the slough darter is quiet or 

 slow-moving water, usually over a soft bottom contain- 

 ing vegetation or debris. In Dismal Creek specimens 

 were collected almost exclusively from mud-bottomed 

 [jools, the few exceptions being occasional strays or in- 

 dividuals overwintering in deep sand-bottomed pools 

 when shallower pools were frozen. 



Elsewhere, as its common name suggests, the slough 

 darter is most often found in roadside sloughs and ditches. 

 It may also occur in a variety of other habitats, such a< 

 springs, slow-moving creeks, small rivers, ponds, oxbow 

 lakes, and backwater pools of very large rivers. In some 

 of these habitats the oxygen content may become low 

 in late summer and fall, although no attempt was made 

 to determine the amount of dissolved oxygen present. 

 For exani|jle, in the fall of 1964 Dismal Creek was 

 reduced to a series of stagnant pools and, when the first 

 freeze occurred in December, a hea\y fish kill resulted. 

 Most of the slough darters were eliminated, but some 

 were among the few fishes surviving. 



.\lthough descrijnions of the habitat are scarce, ref- 

 erences to the occurrence of the species in Oklahoma 

 (Blair 1959), Indiana (Gerking 1945:95), Illinois 

 (Forbes & Richardson 1920:316), and throughout its 

 range (Collette 1962] suggest that the habitat is simi- 

 lar wherever the species occurs. 



An indication of the type of habitat is also provided 

 by the associated species. In Dismal Creek the predomi- 

 nant species are the redfin shiner, NolropU unibralilis 

 (Girard) ; blackstripe topminnow, Funduliis notatus 

 (Rafinesque) ; bluntnose minnow, Pimephalcs notatus 

 (Rafinescjue) ; creek chubsucker. Erhnyzon oblongus 

 (Mitchill) ; creek chub, Srruotilus atromaculatus (Mitch- 

 ill) ; golden shiner, Notemigonus crysolcucas (Mitchill) ; 

 striped shiner, Notropis chrysocephalus (Rafinesque) ; 

 longear sunfish, Lepornis megaloth (Rafinesque) ; green 

 simfish, L. cyancUus Rafinesque; pirate perch, Aphrcdod- 

 tius sayanus (Gilliams) ; white sucker, Catoslomus com- 

 mersoni (Lacepede) ; bluegill, Lepornis macrochirus 

 Rafinesque; and grass pickerel, Esox americanus Gmelin. 



In the study area the slough darter is rivaled in 

 abundance by the bluntnose darter, Ethcosloma chlnro- 

 somum (Hay). Other darters present are the blackside 

 darter, Percina maculata (Girard) ; johnny darter, Ethe- 

 ostoma nigrum Rafinesc|ue: and orangethroat darter, E. 

 spcctabilc (Agassiz). 



REPRODUCTION 



The Reproductive Cycle in the Male 



In mid-February adult males h;i\e already Iwgun 

 to develop breeding coloration. The green or blue-green 

 vertical bands on the sides of some individuals are en- 

 larged and bright, the red spots in the sjjinous dorsal 

 fin are \ivid, and the basal dark pigment is beginning 

 to form. Greater color variation occurs in males than 

 in females, and large 3- and 4-year-old males develop 

 much faster than smaller and \ounger ones. 



By late April the males have reached the peak of 

 coloration. The green bands are brilliant; the spinous 

 dorsal fin is black, except for the subdistal row of bright 

 red dots; and the face and breast are heavily speckled 

 with melanophores. By this time four to six rather large 

 tubercles base formed on the chin (Fig. 3) and numer- 

 ous minute ones are present on the pelvic and anal 

 fins. There is no noticeable enlargement of the genital 

 papilla or change in size and color of the testes. 



By spawning time in late May and early June, the 

 colors have faded somewhat. The timing suggests that 

 colors are used in sex identification and warning away 

 other males while establishing and ]irotecting territories. 

 Lending fiuther support to this infeicnce about the 

 role of color are the absence of color dis|)lays during 

 courtshi]j and the spatial se])aration of males in May. 

 Seldom were two collected near each other then, al- 

 thouyh in winter several could be taken in one haul. Be- 

 cause of the depth and luriiitlily of the water in ■ijjawn- 

 ing time, leriitory sizes could not be deteiniined. 



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