Facultatively internal fertilization and anomalous embryonic development of a non-copulatory sculpin Hemilepidotus gilberti Jordan and Starks (Scorpaeniformes : Cottidae)

Fertilized residual eggs were observed in the ovaries of spent females of a non-copulatory sculpin Hemilepidotus gilberti Jordan and Starks. Fertilize d eggs were present in 23 of 35 females, and approximately 38% of the total residual eggs (n = 227) were fertilized. These eggs were thought to be fer tilized facultatively with spermatozoa that entered the ovary through ovari an fluid during spawning. The high calcium concentration (1.42+/-0.21 mM kg (-1)) in ovarian fluid, which is beyond the threshold concentration require d for fertilization, may anew internal fertilization to occur. Embryos at v arious developmental stages were observed, but all were deformed and surrou nded by unhardened chorions. Since no larvae were observed, all the fertili zed residual eggs would have degenerated in the ovary in accordance with ot her unfertilized residual eggs. These observations suggest that the ovary o f the oviparous fish H. gilberti is an unsuitable environment for embryos t o develop, possibly because it may be unable to supply developing embryos w ith needed elements, such as oxygen. (C) 2001 Elsevier Science B.V. All rig hts reserved.