Characterization of Bacteria Isolated from Landlocked Fall Chinook Salmon Eggs from Lake Oahe, South Dakota

Abstract

AbstractBacteria were isolated from the eggs of landlocked fall Chinook Salmon Oncorhynchus tshawytscha prior to initial placement in vertical‐flow incubations trays 4 h after spawning and also 27 d later at the early eyed egg stage of development. Bacterial densities on the eggs after iodophor disinfection and just before being placed in trays were very low, and most isolates were gram‐positive, nonfermenting cocci. In contrast, bacterial densities on eggs at incubation day 27 exceeded 1 × 107 CFU/egg and were dominated by slow‐growing, gram‐negative coccobacilli. Pseudomonas spp., as well as Flavobacterium (closely related to F. johnsoniae) were also present. Most Pseudomonas and Flavobacterium isolates produced extracellular proteases, making them candidates for further investigation into their possible contribution to egg mortality.