Wo. Watanabe et al., Progress in controlled maturation and spawning of summer flounder Paralichthys dentatus broodstock, J WORLD A C, 29(4), 1998, pp. 393-404
Wild-caught, adult summer flounder Paralichthys dentatus (avg. wt. = 740 g;
range = 264-1,540 g; N = 60), collected in northeastern, US coastal waters
during October 1994, were transported to Vero Beach, Florida in March 1995
and held in 2.6-m(3) indoor tanks through November 1995 under two artifici
al photothermal regimes: (1) natural regime, simulating natural habitat con
ditions; and (2) accelerated thermal regime, with seasonal temperature chan
ges advanced by one month. A third group of fish was held in outdoor tanks
under ambient photothermal conditions. Under all photothermal conditions, o
nset of vitellogenesis was associated with declining daylength and temperat
ure, beginning in the accelerated group, then progressing to the natural an
d the ambient groups. From 20 September to 28 November 1995, 23 vitellogeni
c stage females from the accelerated and natural regimes were implanted wit
h a cholesterol-cellulose pellet containing LHRH-a (100 mu g/kg body wt). F
emales with initial mean oocyte diameters ranging from 258-456 mu m spawned
voluntarily 2.5-5.5 d postimplantation, while no maturational response was
obtained from females with mean diameters ranging from 165-231 mu m. Two f
emales were spawned twice during the study period by LHRH-a pellet implanta
tion. Infrequent, natural spawning without hormone intervention was also ob
tained. Females released from 22.7-396.9 x 10(3) eggs on the first day of s
pawning, with fertilization and hatching rates of 0-93.4% and 0-81.1%, resp
ectively.