Egg quality in fish: Present and future challenges

By J. Bobe. 2015

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Egg quality or oocyte developmental competence can be defined as the ability of the egg to be fertilized and subsequently develop into a normal embryo (Bobe and Labbé, 2010). Similar definitions have been given by other investigators (Kjörsvik et al., 1990; Brooks et al., 1997) to stress that characterization of several features of early developmental success such as embryo survival or the lack of abnormal development is needed to assess egg quality. In aquaculture, as in many other animal breeding programs, the control of gamete quality is of great importance (Migaud et al., 2013). Availability of good quality male and female gametes is necessary to close the lifecycle of a species and obtain subsequent generations. Variation in the availability or quality of gametes can jeopardize subsequent production and limit the possibilities for performing genetic selection. Given the high cost of broodstock rearing, large variations in the quantity or quality of gametes can significantly impact the competitiveness and sustainability of fish farms and aquaculture companies (Bromage et al., 1992). As a consequence, controlling the “on demand” production of good quality gametes is a major issue in aquaculture with important economic consequences (Migaud et al., 2013). While availability and quality of both male and female gametes are important, this is especially true for the female gamete. The female gamete has indeed several features that make its production and availability more difficult to control and optimize than the male gamete. While the male gamete, sperm, can be frozen in most, if not all, fish species, it is currently impossible to freeze female gametes, eggs, due to abundant yolk reserves present in the cytoplasm and high water content in the case of pelagic/floating eggs. In addition, eggs contain maternal factors and other compounds of maternal origin that vary in abundance based on environmental factors and broodstock management techniques. The present article will focus on the female gamete with special attention paid to issues related to the control of its quality including (i) how to measure egg quality, (ii) how egg quality is influenced by environmental factors and aquaculture practices, (iii) the challenges for the future of aquaculture, and (iv) new areas of investigation and expected outputs.

Subfields: Aquatic Science, Nature and Landscape Conservation, Physiology

View Paper: https://www.semanticscholar.org/paper/b6146ef07ef6e6f696e0a1e09638d597d86ce00d