Morphology of ruffe (Gymnocephalus cernuus) protolarvae from the St. Louis River, Lake Superior
Journal of Freshwater Ecology
By: John R. P. French III and Thomas A. Edsall
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Abstract
We describe hatching and the morphological and meristic characteristics of 2.5-5.6 mm long ruffe protolarvae (Gymnocephalus cernuus). Eggs and sperm from St. Louis River ruffe were mixed, producing fertilized eggs that were 0.9-1.2 mm in diameter. Newly hatched protolarvae were 2.5-3.2 mm long. They had 14-15 preanal and 23-24 postanal myomeres, a continuous finfold of even width, unpigmented eyes, and a large anterior oil globule in the yolk sac, and the head deflected over the yolk sac. Pectoral fin buds appeared on the dorsal side of the yolk sac 5 hours after hatching. Two-day-old protolarvae had fully pigmented eyes, and the head was free from the yolk sac. Three-day-old protolarvae were 3.9-4.3 mm long and possessed opercula, gills, pectoral fins, and a functional jaw. Feeding and swimming began about one week after hatching when the yolk sac was almost completely absorbed. Protolarvae grew rapidly at 20-22 degrees C and were 4.9-5.6 mm long after 13 days. Newly hatched ruffe protolarvae are distinguished from other Lake Superior percids by having the fewest preanal myomeres (14-15), the head deflected over the yolk sac, continuous finfold of even width, and a total length of less than 4.0 mm.
Suggested Citation
French, J.R., Edsall, T.A., 1992, Morphology of ruffe (Gymnocephalus cernuus) protolarvae from the St. Louis River, Lake Superior: Journal of Freshwater Ecology, v. 7, no. 1, p. 59-68.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Morphology of ruffe (Gymnocephalus cernuus) protolarvae from the St. Louis River, Lake Superior |
| Series title | Journal of Freshwater Ecology |
| Volume | 7 |
| Issue | 1 |
| Year Published | 1992 |
| Language | English |
| Publisher | Taylor and Francis |
| Contributing office(s) | Great Lakes Science Center |
| Description | 9 p. |
| First page | 59 |
| Last page | 68 |