15 JUNE 1999
G.N. Kent, G.B. Maguire, M. John, M. Cropp, K. Frankish-1998
Journal of Shellfish Research, 17(4): 1065-1070
Abstract:
In a series of trials, broodstock venerid clams Katelysia scalarina were conditioned, or obtained directly from fishing grounds, and stimulated to spawn using thermal cycling. Broodstock, initially with only moderately developed gonad, were sufficiently conditioned for mass spawnings after 8 weeks at 13 C in an indoor recirculating seawater system. Ripe wild broodstock maintained at 20 C could still be spawned after 6 weeks in a similar system. Mean fecundity from mass spawning trials ranged between 0.7 and 2.4 x 10^6 eggs/female, and fecundity estimates for strip spawned individuals varied from 0.3 to 2.2 x 10 ^6 eggs/female. Neither intramuscular serotonin injections (6 x 10^-8 to 1 x 10^-6 mol, total dose), nor strip spawning were reliable methods for producing significant numbers of healthy larvae. Eggs (69 +/- 2 micro m) developed to D veliger larvae (110 +/- 1.3 micro m) within 48 h at 20 C. Metamorphosis to spat (210.9 +/- 2.1 micro m) was observed from day 20 following treatment with 10^-4 m norepinephrine for 60 min on day 19. Larval rearing was not always successful because of bacterial and viral problems and the extended settlement period for this species.
(School of Aquaculture, University of Tasmania, Launceston, Tasmania, Australia, 7250)