UC Davis

Delta smelt (Hypomesus transpacificus) (DS) are an endangered species of fish in the Osmeridae family. They are endemic to the Sacramento/San Joaquin Delta (Delta). This thesis explores the application of an Egg Frame Box (EFB) created by the Lake Suwa Fishing Collective (LSFC) as a means to hatch DS eggs into the Delta in an effort to reduce hatchery characteristics by investigating the fluid dynamics inside and around the EFB through computational fluid dynamics simulations and found that the water decelerates significantly before entering the EFB and further decelerates upon entering the EFB, to a suitable water flow velocity for DS egg incubation. Studying the effects of water temperatures on the hatching and survival rate of DS eggs adhered to the EFB found that temperature plays a significant role in the fertilization and survival of DS eggs, as well as showing that DS eggs can hatch at the water flow velocity found during simulations. Another study focused on testing how alternative egg frame material for the DS eggs to adhere to affects their hatching and survival rate and found that DS eggs can adhere to and hatch from the substrates tested in a similar rate as the egg frame from the LSFC, demonstrating that locally bought, biodegradable items can be used to as a substitute for the egg frame substrate. Last, we studied the effects of different humidities on DS eggs to evaluate how transporting the eggs outside of water will affect their hatching rate and found that DS eggs are extremely sensitive to being removed from their aquatic environment and should remain submerged throughout their transport to the deployment site. Overall, this thesis provides valuable insight into DS eggs in an effort to restore the wild population from its endangered status in the Delta.