Scientists at the Eastern Ecological Science Center are working with partners across the Atlantic Coast to better understand the impacts of bycatch on the recovery of shad and river herring populations.
Genomic Mixed Stock Analysis of American Shad and River Herring to Support Interstate Management
American Shad (Alosa sapidissima), Blueback Herring (Alosa aestivalis), and Alewife (Alosa pseudoharengus; collectively “alosines”) once supported large fisheries along the U.S. Atlantic coast. However, impassable migration barriers, declines in habitat quality, and exploitation have led to declines in many spawning populations. Substantial resources have been invested to support the recovery of alosines populations, yet results have been mixed. For example, some fish passage projects have resulted in large increases in populations, whereas others have had disappointing results, suggesting that other factors may be inhibiting recovery.
As anadromous (migrating up rivers from the sea to spawn) fishes, alosines spend much of their life history in estuarine and marine environments where they may form mixed stock aggregations. There is a critical need to be able to distinguish among populations or management units when individuals are encountered away from the areas where they were born. An enhanced understanding of stock composition provides critical information on the status and trends of specific populations and offers much-needed insight into how fisheries bycatch (a fish or other marine species that is caught unintentionally while fishing for specific species or sizes of wildlife) may be impacting recovery efforts.
As part of the Eastern Ecological Science Center’s initiative to increase science support for the Atlantic States Marine Fisheries Commission (ASMFC), the center started an alosine genomics program in 2020. This effort is under the direction of Research Fish Biologist Dr. David Kazyak and his postdoc, Research Biologist Dr. Miluska Olivera-Hyde (Akima Systems Engineering). The first objective of the project is to establish a tissue repository for shad and river herring, which will be an essential resource to support mixed stock analysis at the USGS and other institutions. We are working with partners along the Atlantic coast to obtain tissue samples from different locations to augment current genetic baselines and to date have received samples from more than 10 agencies. We are now working with the New Jersey Division of Fish and Wildlife on an effort to characterize the stock composition of American Shad captured in Delaware Bay. We are also working with the Northeast Fisheries Observer Program to obtain samples from shad and river herring that are incidentally captured in commercial fisheries for Atlantic Herring and Atlantic Mackerel. Bycatch associated with these fisheries is a management concern, in part because impacts to coastal populations are poorly understood.
Another objective of the project is to support the development of genomic baselines for shad and river herring. Through partnerships with outside groups (e.g., Cornell University and UC Santa Cruz), we are helping to develop or improve panels for shad and river herring, including the establishment of efficient approaches to screen large numbers of samples across many loci.
Our ultimate goal is to characterize the stock composition of shad and river herring captured in coastal fisheries, which will be accomplished by comparing the genetic signature of individual fish to baseline reference populations across the coast. This information will be used to support stock assessments and help managers better understand how fisheries bycatch impacts the recovery of local spawning populations.