All subsequent reductions in numbers were random. After set, about 10,000 to 20,000 spat per line were randomly selected for the nursery. Screening off small larvae was minimized during larval development. In addition, highly skewed sex ratios in some lines sometimes made it difficult to find the right sex from the right line for a particular cross. In the project hatchery, the 2 million fertilized eggs per line target was sometimes compromised by the experimental efforts to use 1-year-old broodstock. Oyster seed from ASI’s selected lines is available to growers who raise the oysters in baskets on racks in intertidal waters. The project also requires decisions about what traits and families to propagate, and developing a viable commercialization plan acceptable to all the participants. The challenges have been many, including working in remote locations, overcoming the logistics of rearing 50 separate families annually, and maintaining lines across five commercial grow-out farms spread over 1,500 km. Mass selection with over 50 individuals per line, family selection, and inbred lines have all been part of the evolving strategy. Commencing in 1997 with support from the Fisheries Research and Development Corp., a research team from the Commonwealth Scientific and Industrial Research Organization, University of Tasmania, and industry started a project to improve the breed. 1: Mean wet weight of oysters from various F4 families relative to commercial controls Genetic variabilityĪn assessment of genetic variability indicated no detectable difference between the Tasmanian population of Pacific oysters and the parental stocks in Japan. The oysters are largely sold in the half-shell form. Australian grow-out production of Pacific oysters – primarily intertidal in baskets on racks – is worth about AUS $30 million (U.S. Pacific oyster seed is now produced at several hatcheries and grown out around Tasmania, South Australia, and parts of New South Wales. Small populations of Pacific oysters were eventually established in some locations around the state, but the industry remained quite small until the development of hatchery technology. Nonprofit Australian Seafood Industries responsible for 20 percent of spat sales The selection process has led to Pacific oysters with more meat and controlled coloration.Ĭonsiderable quantities of juvenile Pacific oysters ( Crassostrea gigas) were brought from Japan to Tasmania, Australia, in the late 1940s and early 1950s to establish a new oyster industry, which had earlier been based on the local, slow-growing flat oyster ( Ostrea angasi).
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