Production, Behavior, and Survival of Juvenile Shad and River Herring
USGS is conducting research to better understand biology, behavior, and survival of juvenile fishes that travel between fresh and saltwater to complete their lifecycles. Migratory fishes as such as herring and shad are vital components in riverine and coastal ecosystems, transporting food and nutrients between fresh rivers and the ocean. They are also an important forage fish for predators in freshwater and marine environments.
What is the issue?
American shad (Alosa sapidissima) and river herring (a collective term for blueback herring (Alosa aestivalis) and alewife (Alosa pseudoharengus)) are anadromous fish, meaning they must migrate out of rivers to the ocean to complete their lifecycle. Survival during the juvenile phase of their life-history can limit population size and resilience to environmental fluctuations. Understanding production as well as sources of mortality is important for managing populations.
What is at stake?
Populations of shad and river herring have undergone severe declines in recent decades largely due to dams and other migratory barriers. High mortality due to barriers that block movements of adults or juveniles can lead to excess nutrients in freshwater environments while also depriving valuable marine and freshwater fisheries of important forage stock. A better understanding of biology, behavior and survival will help to identify passage solutions that can improve production and reduce mortality of species such as shad and river herring as well as other migratory fishes.
What is our approach?
USGS is examining fundamental biological questions such as the response of migratory fish species to turbulence and other hydraulic conditions, swimming energetics and capabilities, and factors contributing to spawning success and migration.
Specifically, through this research USGS will:
- Identify sources of mortality for juvenile shad and river herring
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Quantify mortality associated with downstream passage at hydroelectric dams and other barriers and identify solutions that minimize mortality
Researchers are working in both field and laboratory settings. Within a laboratory flume at the S.O. Conte Research Laboratory, fish experience fish passage structures under conditions similar to those experienced in the wild and devices that are experimentally modified along with their operational conditions to measure the effects of these treatments on fish survival and behavior. Field work focuses on tracking juveniles as they migrate downstream, with particular attention paid to dams and efforts to provide safe, timely, and effective passage.
What are the benefits?
Findings from this research will serve management agencies, hydroelectric utilities, and others concerned with restoration, management, and harvest of shad, river herring and other migratory species. Because of the vital ecological role played by these species, gaining a better understanding of the extent of juvenile fish mortality and solutions to minimize it will also benefit marine and coastal fisheries that depend on these species.
