CHALLENGES IN DEVELOPING A SELECTIVE BREEDING PROGRAMME FOR THE GREAT SCALLOP (Pecten Maximus)

摘要

The development of a selective breeding programme for the great scallop requires knowledge in several areas: First, to allow for selection also for traits that cannot be recorded on the live breeding candidates a pedigreed nucleus population is needed. This requires the separate rearing of a large number of full-sib families until the animals are large enough for tagging. As the number of individuals needed per family is not large (< 500), a few litres of rearing volume for each family should be enough, as opposed to the large tanks (several m3) used in commercial hatcheries in which several egg, or larvae groups are pooled together (Andersen et al. 2000). The challenge is therefore to develop a compact and reliable separate rearing system of families for which the magnitude of the environmental factors common to full-sibs is low for the traits selected for, and to develop a system for individual tagging of a random sample of the individuals from each family group at an early age that can be pooledand reared together until harvest size. An important breeding objective trait for the great scallop is the growth of the adductor muscle. If this trait can be recorded non-invasive on the live breeding candidates, selection can be practised also withinfamilies thus increasing both the selection intensity and accuracy and thus the genetic gain. For this purpose we investigated both external measurements on the animals, near infrared (NIR) technology, which is applied with success on the edible crab (Wold et al., 2010), and X-ray imaging. Since the great scallop is a functional hermaphrodite, it is of crucial importance to be able to separate egg and sperm prior to fertilization so that selfing and thus a reduction of the genetic variance can be avoided (Martinez et al., 2007).