Effects of self-fertilisation and other factors on the early development of the scallop Pecten maximus

Adult Pecten maximus (L.) were dredged off north-east Anglesey, Wales, UK, during 1981. A 2×5 factorial mating was carried out involving self- and cross-fertilisation and the use of stripped spermatozoa. Assessments of yield, normality, and larval size were made at the D larva stage and larval size and mortality were measured after a fortnight's growth of the veligers. Underlying genetic variation was evident at all stages, with egg and sperm generally having a significant interactive effect. Cultures sired with stripped spermatozoa had fewer larvae, with more abnormality, grew slower and suffered higher mortality than most other cultures. Larvae from selfed cultures grew significantly slower than all other larvae. Data from past larval cultures also show that selfed larvae have a reduced growth rate. it is suggested that stripped spermatozoa may interfere with egg and sperm interaction at fertilisation, thus reducing the viability of larvae. On the other hand, the poor growth rate of selfed larvae is probably due to overall reduced heterozygosity compared to outbred larvae.