Seasonal Changes in Reproductive Activity in the Potter's angelfish (Centropyge potteri) in Kaneohe Bay, Hawaii

Abstract

Potter's angelfish, Centropyge potteri, is a protogynous hermaphrodite, with the alpha female of a harem becoming male under the proper social conditions. Gonads and plasma samples were collected from females every 6–9 days for 1 year, and then for every 4–6 weeks for another year. The gonadosomatic index (GSI) of females remained below 1% from July until December. Starting from the first week of December, large spikes occurred in the GSI, fluctuating from 1.4% to 4.1% and falling below 1% in June. Plasma concentrations of estradiol-17β were relatively low (1–2 ng ml−1) between July and November. Beginning in the third week of November, large spikes of plasma estradiol-17β were observed, fluctuating from 0.5 to 5 ng ml−1. This pattern continued until the third week of May, and then estradiol-17β levels remained low for the rest of the year. Estradiol-17β levels showed a highly significant correlation with GSI. Estradiol-17β levels during late vitellogenesis and final maturation were significantly greater than those of the other stages. These results suggest that the spawning season of the Potter's angelfish is from December to June. One of the causes of the large fluctuations in GSI and plasma estradiol-17β within the spawning season appears to be due to the fact that Potter's angelfish is an asynchronous daily spawner.