Protopopescu, G.C., Beal, B.F.
A critical aspect of blue mussel (Mytilus edulis L.) aquaculture is industry dependence on a highly variable supply of wild seed. The objective of this study was to investigate responses of cultured pediveligers of blue mussels to different types of rope collectors. The study consisted of two trials in which competent larvae (approximately 5,000 per experimental tank—400 L) were exposed to rope collectors (polyethylene and polypropylene) exhibiting diverse structural features such as long loops, short loops, long filaments, short filaments, and smooth (Trial I—four rope types; Trial II—five rope types). In Trial I, rope segments (3 cm long) were placed at two different levels in four culture tanks (top and bottom of water column). In Trial II, segments were placed in the middle of the water column in six culture tanks. After 5 days, rope collectors were removed from experimental tanks and the number of settled larvae on each segment was counted. Rope collectors with the highest structural complexity/greatest surface area (long loops) elicited the strongest settlement response (highest densities) of mussel larvae, whereas those with the lowest complexity/least surface area (smooth) elicited the weakest response. Position within tank (top versus bottom; Trial I) had no significant effect on settlement density. Hatchery-reared mussel seed could be a reliable alternative to wild seed, and ropes with complex features should be used as larval collectors as they enhance settlement density which, in turn, could reduce production costs.