Movement and Population Dynamics of Green Sturgeon

Green Sturgeon (Acipenser medirostris) are large anadromous fish vulnerable to freshwater management decisions. The Southern population of the Green Sturgeon spawns in the Sacramento River watershed of California in the United States and is listed as a threatened species under the Endangered Species Act. Management and conservation of this species requires accurate population assessments of breeding adults. In this study we develop a model to predict the percentage of breeding Green Sturgeon present within the spawning grounds during any given week within the spawning season. We find that a model incorporating spawning ground water temperature and flow velocity, day of the year, and Water Year type (a statewide water stress classification) best predict the percent of the spawning population within the spawning reach. This implies a complex interaction between temperature and flow velocity. Understanding what percent of the breeding population is present throughout the summer will assist managers in determining the abundance of the Green Sturgeon spawning population when using summer surveys.