Embryonic, larval and juvenile development of the roughskin sculpin,Trachidermus fasciatus (Scorpaeniformes: Cottidae) |
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Authors: | Naohiko Takeshita Norio Onikura Seiichi Matsui Seirô Kimura |
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Institution: | (1) Department of Applied Aquabiology, National Fisheries University, 2-7-1 Nagatahonmachi, 759-65 Shimonoseki, Japan;(2) Fishery Research Laboratory, Kyushu University, 2506 Tsuyazaki, 811-33 Fukuoka, Japan;(3) 4-2-24 Kashii, 813 Fukuoka, Japan |
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Abstract: | Embryonic, larval and juvenile development of the catadromous roughskin sculpin,Trachidermus fasciatus, were described using eggs spawned in an aquarium. The eggs, measuring 1.98–2.21 mm in diameter, were light reddish-yellow
and had many oil globules, 0.05–0.18 mm in diameter. Hatching occurred 30 days after spawning at 2.3–11.3°C. The newly-hatched
larvae, measuring 6.9–7.3 mm BL, had a single oil globule, 9–10+25–26=34–36 myomeres and 6 or 7 large stellate melanophores
dorsally along the gut. The yolk was almost resorbed, number of pectoral-fin rays attained 16–17, and two parietal, one nuchal
and four preopercular spines were formed, 5 days after hatching, at 8.2–8.4 mm BL. The oil globule disappeared, and one supracleithral
spine was formed, 11 days after hatching, at 8.9–9.5 mm BL. Notochord flexion began 15 days after hatching, at 9.7–10.3 mm
BL. A posttemporal spine was formed 20 days after hatching, at 10.7–10.9 mm BL. The first dorsal fin spines (VII–VIII), second
dorsal fin and anal fin rays (18–19, 16–18, respectively) appeared 23 days after hatching, at 12.0–13.7 mm BL. The pelvic
fin spine and rays (I, 4) were formed and black bands on the head and sides of the body began to develop 27 days after hatching,
at 13.8–15.8 mm BL.
Newly-hatched larvae swam just below the surface in the aquaria. Preflexion larvae (8.9–9.5 mm BL), in which the oil globule
had disappeared, swam in the middle layer, while juveniles (13.8–15.8 mm BL) began swimming on the bottom of the aquaria.
Swimming behavior observed in the aquaria suggested that the fish started to change to a demersal existence at the juvenile
stage. |
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Keywords: | Egg larva juvenile Trachidermus fasciatus Japan |
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