Artificial Fertilization And Rearing Of Cerastoderma Lamarcki In The Laboratory
Additional data on artificial fertilization and rearing of the larvae of Cerastoderma lamarcki (Reeve) are presented. Temperature shock was used to stimulate ripe cockles to release large quantities of viable gametes. High rates of fertilization (>80 %) were recorded in salinities ranging from 15 to 35 ‰. However, the best salinity for quick embryonic development and larval hatching success seems to be 25 – 30 ‰. No larval hatching was recorded in salinities below 1 5 ‰. Crowding of eggs had little effect on fertilization success, but satisfactory embryonic development and larval hatching occurred at densities lower than c700 eggs/cm². The sizes of the newly hatched D-larvae decreased with increasing egg density in the size range 111.0-120.7 µm. Of 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 work shows C. lamarcki to be well adapted to bivalve hatchery procedures. The relative ease of maintaining its laboratory cultures strengthens previous claims that it would be a better choice for controlled commercial production than its sibling species C. edule (L.).