The life history and comparative ecology of the sharphead darter (Etheostoma acuticeps)

A study of the sharphead darter, Etheostoma acuticeps Bailey, was conducted to determine its life history and competitive feeding relationships with both syntopic darters and other members of the subgenus Nothonotus. Information from this and other studies indicate that other Nothonotus (E. maculatum, E. camurum, and E. rufilineatum) have similar diets comprised of 66 to 78% Chironomidae and 10 to 24% Baetidae and Simuliidae. In sharp contrast to its relatives, E. acuticeps consumes 31% Simuliidae, 30% Baetidae, and only 26% Chironomidae. Etheostoma blennioides, a darter syntopic with E. acuticeps, consumes 80% Chironomidae, which is a function of the subterminal position of its mouth. Another darter common in E. acuticeps habitat, E. zonale, eats 47% Chironomidae and 39% Baetidae, which is associated with its plant-loving habits and subterminal mouth. The sharphead darter is unique in its forceps-like mouth, very precise feeding behavior, and preference for fast water over a substrate covered with Podostemum.

The sharphead darter breeds from late June until mid-August, making it one of the latest spawning darters. Fecundity varies from 100 eggs per 39-mm female to nearly 300 per 55-mm female. Eggs apparently are buried in sandy substrate next to rocks, as in E. camurum and E. rufilineatum. Breeding males display aggression by intense color changes and biting other males.

Sharphead darters live to an age of three years, males reaching a maximum standard length of almost 70 mm, while the females only reach about 55 mm. Sexual maturity is achieved at one year.

Sharphead darters typically inhabit the swiftest portion of riffles, with a surface velocity of 2 m/sec. The substrate is rubble and small boulders 5 to 20 cm in diameter, usually well encrusted with Podostemum ceratophyllum. Depth is commonly 15 to 30 cm. Current distribution of the sharphead darter, includes the lower 6 km of the Cane River in North Carolina, the lower Nolichucky River between Davy Crockett and Douglas reservoirs, and possibly the lower kilometer of two of the South Fork Holston River above South Holston reservoir in Virginia.