Fertilization success of the New Zealand geoduck, Panopea zelandica:

摘要

Valuable aquaculture and fisheries industries for the North American geoduck, Panopea generosa, have driven interest in developing similar ventures for other geoduck species including P. zelandica from New Zealand. However, little is known about the fertilization kinetics of this species, or the conditions under which the amount and quality of larvae can be maximized. We determined the effects of sperm concentration, gamete age and contact time on the fertilization success of P. zelandica using an extended-Vogel-Czihak-Chang-Wolf (EVCCW) model. The model provided a good fit to laboratory data when applied to individual contact times. For a contact time of 10 s, optimal fertilization was achieved at concentrations of approximately 10 4 sperm mu L-1, but this decreased to as little as 10 2 sperm mu L-1 for contact times of several minutes. Optimal fertilization was always <100% (max. observed 70%) and the proportion of fertilized eggs decreased rapidly at sperm concentrations above the optimal. According to the model this was due to a slow block to polyspermy. If commercial hatchery facilities ensure that broodstock are in ripe condition, and use sperm <30-min old, then optimal fertilization can be expected at sperm densities of 10 2-10 3 sperm mu L-1 at contact times of 5-10 min