Fish-Holding-Associated Stress in Salvaged Fishes at Reclamation Facilities
Over the past three years, we have been using physiological stress indices to study the deleterious effects of the fish salvage process at the Tracy Fish Collection Facility (Tracy, California) and Reclamation's Hydraulics Laboratory (Denver, Colorado). We have examined holding tank design as well as fish removal and transfer methods, and how they relate to acute physiological stresses and potential direct and indirect mortality experienced by salvaged fishes.
The next logical step and aim of this Science and Technology (S&T) research project is to examine the physiological changes in plasma constituents attributable to capture and handling stress of salvaged fishes throughout a normal holding period. A better understanding of the stressors affecting fish capture and handling can lead to practices that reduce stress and its detrimental effects, thereby increasing survival of entrained fishes and reducing incidental take of threatened species in a manner that does not hinder the delivery of water.
Need and Benefit
Declines of several fish species throughout the Western United States may threaten to disrupt water delivery systems. Water diversions are suspected of being one of the primary causes for the losses of fishes through entrainment. California water officials halted water exports from the Sacramento-San Joaquin Delta in the spring of 2007 after rising numbers of endangered fish were thought to be killed. Water is vital to the growth and prosperity of the Western United States and recent lawsuits from the California Department of Fish and Game and environmental groups have dealt major blows to Delta water export. Water resource agencies will have to comply with tougher environmental standards in the near future and will have to lessen their impact on fish and wildlife while providing water for agriculture and municipalities.
Operations of Reclamation facilities at water diversions and dams require proper screening, passage, capture, and handling of fish. These functions are of major importance for the survival of fishes impacted by Reclamation; however, handling stress associated with entrainment may inadvertently harm the fish that Reclamation is attempting to save. Exposure of fishes to environmental stressors, such as capture and handling, can be a great concern to fisheries biologists, in that extreme or prolonged stressors may plague fish performance and overall health, adversely affecting population size and sustainability. Measuring the physiological stress and potential direct and indirect mortality experienced by fishes during the different components of Reclamation operations is vital to understanding its negative impacts. Results of this research and a research project funded by the Tracy Area Office will provide information on methods to reduce the harmful effects of entrainment and handling, leading to a reduction in the incidental take of fishes and a reduction of indirect mortality from sublethal stressors. The literature on the physiological effects of capture and handling stress on entrained or salvaged fish species through daily operations at Reclamation and other water resource agencies' facilities is scant and needs to receive more research attention.
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