Effects of loading density during transport on physiological stress and survival of Sacramento-San Joaquin Delta fishes

Truck transportation from the Bureau of Reclamation's Tracy Fish Collection Facility in California's Sacramento-San Joaquin Delta is the final phase of a multi-component process that results in the capture and release of >50 fish species, thereby preventing entrainment at a downstream water pumping facility. Fish-transport tables (termed Bates Tables) developed in 1955 do not take into consideration the fish loading process, commonly transported sensitive species, or physiological effects of elevated densities. To investigate suitability of the Bates Tables, effects of loading and transport at recommended and twice-recommended transport densities on physiological stress and survival of threadfin shad (Dorosoma petenense), Chinook salmon (Oncorhynchus mykiss), and striped bass (Morone saxatilis) were tested. Density did not have a significant effect on fish survival or physiological stress, as indicated by blood plasma constituent levels. At both densities, mean post-transport (168 hour) survival of all species was high (>98%), and ammonia and carbon dioxide levels increased in transport water as a result of fish metabolism, but levels remained below lethal levels. Among all species tested blood cortisol, glucose, and lactate levels followed a predictive adaptive response, with levels tending to peak immediately following transport and returning to basal levels within 24 hours.