The Iceland scallop, Chlamys islandica (O.F. Müller) in Breidafjördur, west Iceland. I. Spat collection and growth during the first year

Abstract

Spat of the Iceland scallop Chlamys islandica (O.F. Müler), was artificially collected, using onion bags of 6 mm mesh size filled with monofilament of 0.4 mm, and polyethylene bags of 4.5 mm mesh size filled with monofilament of 0.2 mm. The spat collectors were placed at 25–35 m depth in Breidafjördur on the west coast of Iceland, in the middle of July 1988. The settlement of the spat was observed in the middle of September. No significant difference was found in the settlement at different depths but it varied greatly according to the diameter of the monofilament in the bags. Heaviest settlement was observed on the thinner monofilament (0.2 mm). The instantaneous growth rate was highest from the middle of September to the middle of October (3.6%/day) but decreased during the winter. In May the growth increased again concurring with an observed increase in sea temperature and abundance of phytoplankton. In September 1989, 1 year after settlement, the spat had reached an average size of 9.8 mm. Some evidence of secondary migration was observed for Chlamys islandica 1 year after settlement.