Lake sturgeon (Acipenser fulvescens) are endemic to the Laurentian Great Lakes basin and hold significant ecological and cultural value. Historically, A. fulvescens were most abundant in the Great Lakes region of the US and Canada, but European colonization led to massive decimation of populations across North America. Due to modern conservation efforts, A. fulvescens populations are now increasing regionally, but most locations require aquaculture-stocking programs to sustain progress. Live feeds are standardly used to raise A. fulvescens, but the cost, labor, and nutritional variability associated with maintaining live feeds is a major operational challenge. Identifying a nutritionally optimized, cost-effective formulated diet would bolster these sturgeon-breeding programs. The relationship between diet, the intestinal microbial community, and fish health is one important, but often-overlooked, component of feed formulation for aquaculture practices. In this study, we collected baseline data on the relationship between growth outcomes for A. fulvescens fingerlings and their intestinal microbial community composition during formulated feeding trials conducted in a flow-through aquaculture system. The trials consisted of: 1) with and without replacement of “typical” live feeds by formulated diets and 2) across feeding rates spanning 0.5-12% body weight per day.
Results/Conclusions
Across all diet trials, we found the intestines of A. fulvescens fingerlings had relatively low diversity and were dominated by the microbial genera Plesiomonas, Vogesella, and Enterobacter. These genera have been found to be abundant in indoor captive-bred zebrafish intestines, which suggests indoor rearing conditions may contribute to intestinal microbial assembly. Inter-fish community composition variability was high, but community composition shifts were associated with both fish age and feed type. Feeding rates influenced fish weight gain, with maximum weight gain achieved over a 1-week period at a feeding rate of 9.2% body weight per day at 63 dpf (days post-fertilization) and 6.6% at 77 dpf. However, there was no significant relationship between feeding rate and the intestinal microbial community composition.