HORMONE-INDUCED SPAWNING AND DEVELOPMENT OF ARTIFICIALLY REARED LARVAE OF THE WEST AUSTRALIAN DHUFISH, GLAUCOSOMA-HEBRAICUM (GLAUCOSOMATIDAE)

Hormone-induced spawning of the West Australian dhufish, Glaucosoma he braicum (Glaucosomatidae) is reported, and the artificially-reared egg s and larvae are described. Hormones tested were hCG, Ovaprim and LHRH analogue, the last both as implants and in a saline solution. Late-st age fertilized eggs are spherical (960-1200 mu m), possess a pigmented oil globule (210-273 mu m) anteriorly on the unsegmented yolk, and ha tch in about 32 hours at similar to 23 degrees C. Newly hatched larvae (1.75-2.10 mm) have a prominent yolk sac which is resorbed after 3.3 days. The mouth becomes functional from Day 3, first feeding occurs fr om Day 3.5 and the inflated gas bladder is first observed from Day 4.3 . Larvae examined (1.75-8.13 mm) have a moderately deep body, 24-25 my omeres, early-forming pelvic fins that are heavily pigmented by the po stflexion stage, small to moderate head spination, no gap between anus and anal-fin origin, and a distinct pattern of pigmentation. Notochor d flexion occurs between 3.42 (15 days) and 4.83 mm (25 days), and the transition to the juvenile stage starts from similar to 8 mm (45-46 d ays). Comparisons with taxa with similar larvae show that Glaucosoma l arvae share some similarities with pempherid larvae, although the evid ence is not sufficient to strengthen the view that both groups are clo sely related.