![]() Ideally, they would allow female fish to be sorted in the fall segregating the fish that are in late vitellogenesis from other fish based upon the degree of ripeness so that fish 65 of the appropriate stage of maturity can be harvested during the winter and spring. New methods should be less invasive, preferably non-invasive and minimally stressful to fish, and quick. We also need new methods to predict sturgeon maturity as an alternative to the ovarian biopsy and oocyte PI measurement. To improve harvest prediction, we need to have a better understanding of the biochemical and physiological changes during ovarian maturation and how these changes correlate with roe quality. ![]() Even the early stage of atresia causes a reduction in the firmness, flavor, and shelf life of caviar. ![]() Females undergoing the first stage of atresia may appear to be normal at harvest but once processed, the caviar may have to be downgraded due to egg softness and its yield severely diminished due to the loss of eggs bursting during processing and handling. When applied repeatedly, surgical biopsy often results in decreasing caviar yield and quality due to ovarian follicular atresia, the phagocytosis of ovarian eggs. This technique is accurate but invasive and stressful, time consuming, and not an effective tool for handling a large number of fish. PI indicates morphogenetic changes in the ovarian follicle occurring during late vitellogenesis and leading to maturational competence. Oocyte PI is a ratio of the distance of the germinal vesicle from the animal pole to the oocyte animal-vegetal axis diameter. Optimizing harvest time could extend the caviar production season.Ĭurrently, the only means to assess ripeness of white sturgeon ( Acipenser transmontanus, Acipenseridae) females and the proper time of harvest is measurement of oocyte polarization index (PI) requiring a surgical biopsy. Accurately predicting maturity is also commercially important in aquaculture and stock management if a uniform and consistent egg size and firmness are to be obtained and caviar yields are to be optimized. Sturgeon brood stock management in aquaculture and in conservation programs for endangered species will benefit from the improved staging of fish by maturity. ![]()
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