Abstract
Iwagaki oyster Crassostrea nippona spat were experimentally collected using soft resin spat collectors with different shapes and surface characteristics, and the efficiencies of the different collectors for the artificial cultivation of single-seed iwagaki oysters were compared. The number and growth of settled spat were compared between the different collectors and after removing the seeds from the collector. The survival rates of seeds produced on the different separators were compared after rearing for several months. The results showed that polypropylene, which is highly durable and can be used repeatedly, is well suited for constructing collectors. Umbrella-shaped collectors with rough surfaces (arranged in a lattice-pattern projection) promoted settling by spat, but the growth rate of spat on such collectors was slightly inferior compared to the growth rates obtained using smooth, flat collectors under the same conditions. Rough surfaces were highly effective for promoting both spat settling and for preventing damage to the shells when spat were removed from the collectors, increasing spat survival. Thus, rough-surfaced umbrella-shaped spat collectors, with collection efficiencies that are comparable to the currently used scallop shell collectors, will likely improve the efficiency of single-seed oyster production.
