Grant: Discovery Grants Program - Individual

Aquaculture production now represents a significant portion of all fish consumed. There has been unbelievable growth of an industry barely 30 years old. Aquaculture science is also very new and has yet to address many challenges associated with this industry. For example, unlike agriculture, very few breeding programs exist for fish production. One of the most difficult aspects of developing species for aquaculture is managing and producing high quality gametes that will produce fish with traits leading to ""optimal performance"" in an economic context. *Egg quality is an issue in aquaculture and is largely controlled by female diet. Space and time requirements for determining the effect of diet manipulation on egg quality are substantial, particularly for larger, longer-lived fishes. Consequently, developing broodstock diets is difficult, time consuming and expensive. Controlling nutrition at the level of the embryo has the potential to be a much more cost-effective means of managing egg quality. We have developed the first successful microinjection/manipulation system to control yolk size in living fish embryos. I propose to further modify this method, providing a fast and inexpensive approach for development of broodstock diets. I propose to manipulate essential fatty acid (EFA) profiles within developing zebrafish embryos. EFA's serve various essential functions in fishes. For example, DHA has been implicated as an EFA for normal development of nervous system, sensory organs, and eyes. We will alter the fatty acid profile of fish eggs by microinjection/manipulation of DHA and other essential fatty acids, such as EPA and ARA, to examine how they affect development, survival, and performance characteristics in zebrafish. This work will be the first step in developing a microinjection/manipulation protocol to contribute to development of broodstock diets for aquaculture. *Eggs are typically viewed as a limited resource while spermatozoa are considered unlimited. However, this is not necessarily the case; for many fish species only a limited quantity of spermatozoa are produced each breeding season. Therefore, to manage gamete use in a culture setting and understand recruitment in wild populations, we need to know how many spermatozoa are required to fertilize each egg, spermatozoa behaviour and longevity after exposure to water, and how long eggs are receptive to fertilization post-release. In this proposed work, we will focus on sperm and egg interactions in sturgeon. Sturgeon are among the most valuable and endangered fishes in the world. Currently, global supplies of caviar from wild harvesting and aquaculture operations are low and the resultant demand for this highly valued product has put further pressure on remaining wild sturgeon stocks. My students and I will focus on assessing sperm quality and sperm-egg interactions for three species occurring in Canada that are of both aquaculture and conservation interest: shortnose (Acipenser brevirostrum), lake (A. fulvescens), and white (A. transmontanus) sturgeons. Implications of this work are two-fold. For production purposes, baseline data on sperm characteristics informs selection of high quality males for broodstock while research on sperm/egg interactions reveals sperm-to-egg ratios, contributing to effective gamete management. This work also provides insight into sex ratios required to sustain wild populations as well as information on reproductive strategies. Further development of sturgeon aquaculture will not only bring about economic gains, but will also alleviate pressure on wild populations, contributing to the conservation of these imperilled fishes. Three graduate students and 7 undergraduate students will be trained through funding for this research program.