Artificial fertilization and rearing of Cerastoderma Lamarcki (reeve) in the laboratory

Abstract

Additiona l data on artificial fertilization and rearing o f the larvae o f Cerastoderma lamarcki (Reeve) are presented. Temperature shock was used to stimulate ripe cockles to release large quantities of viable gametes. Hig h rates of fertilization (>80fo) were recorded in salinities ranging from 15 to 35%o . However, the best salinity for quick embryonic development and larva l hatching success seems to be 25-30% o . No larva l hatching was recorded in salinities below 15%o . Crowdin g of eggs had little effect on fertilization success, but satisfactory embryonic development and larva l hatching occurred at densities lower than c700 eggs/cm^. Th e sizes o f the newly hatched D-larva e decreased with increasing egg density in the size range 111.0-120.7 pm. O f the five different micro-algal food organisms tested on the larvae, Isochrysis aff. galbana (clone T-ISO ) (see Ewart & Epifanio , 1981) produced the best growth rate and minimum mortality. This wor k shows C. lamarcki to be well adapted to bivalve hatchery procedures. Th e relative ease o f maintainin g its laborator y culture s strengthens previous claims that it would be a better choice for controlled commercial production than its sibling species C. edule (L.) .