Induced spawning of two western tropical Pacific groupers, Plectropomus areolatus and Epinephelus fuscoguttatus, in Palau

In May and June 1991, 10 squaretail coral (Plectropomus areolatus) females ovulated 34-36 hours after the first of two intramuscular injections of human chorionic gonadotropin (HCG), producing 4,001,000 eggs; four fish later released an additional 1,792,000 eggs, and another 1,630,000 eggs were found in the holding tank. Five females ovulated naturally several hours after capture (about 12 hours before the new moon in June), producing 856,000 eggs. In June, three brown-marbled grouper (Epinephelus fuscoguttatus) females ovulated 37-39 hours after the first of one or two HCG injections, producing 5,035,000 eggs, with another 42,000 found in the tank. Coral trout egg diameter range was 687-814 µm (mean 754 µm) and oil globule diameter range 170-257 µm (mean 213 µm). Brown-marbled grouper egg diameter range was 743-826 µm (mean 789 µm) and oil globule diameter range 187-251 µm (mean 215 µm). In most cases, fertilization and hatching rates were high. Induced spawns produced 1,755,000 coral trout and 3,791,000 brown-marbled grouper hatchings.