Genetics of the Pacific oyster

• Main Author: Lannan, James E.
• Other Authors: Simon, Raymond C., Fisheries and Wildlife, Oregon State University. Graduate School
• Format: Doctoral or Postdoctoral Thesis
• Language: English; unknown
• Published: Oregon State University
• Subjects: Pacific oyster; Crassostrea gigas
• Online Access: https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/q811kn84d

Variances among individuals within populations are influenced by environmental and genetic factors. Utilizing quantitative genetic theory, environmental and genetic components of variance have been compartmented for a variety of quantitative characters of the Pacific oyster, Crassostrea gigas. A significant genetic component of variance in a quantitative attribute related to reproductive fitness implies that selection is being effected upon the system. In the present investigation, the variance of larval survival has been subjected to a genetic evaluation. A statistically significant genetic component of variance has been observed. It is concluded that under the conditions observed, genetic selection is inherent in hatchery operations directed toward the management of this species. The genetic implications of these selective practices are discussed in the text of this thesis. It is suggested that this method for the genetic evaluation of hatchery practices is appli­cable to other aquatic animals which are propagated in hatcheries. The genetic and environmental components of variance have been estimated for several other economically significant attributes of C. gigas. In every case, a significant genetic component of vari­ance was observed. Further compartmenting of the genetic variance into additive and non-additive genetic components revealed that a large non-additive component was present in every case ob served. This is interpreted as being a consequence of introducing a wild animal into a selective, quasi-domestic culture situation. It is con­sidered likely that after several generations of hatchery culture, selection plateaus will be attained and additive genetic variance will increase relative to other variance components. Based upon these observations, a method for selective breeding of oysters has been proposed. It is suggested that progeny testing is the breeding method best suited for the early stages of selective breeding with oysters and probably for aquaculture in general. Pre­liminary tests of ...