VIMS has been monitoring American shad abundance since 1998. Recent acoustic tagging studies investigated shad behavior during spring spawning migrations in Virginia's rivers.
In 2003, 29 adult shad on their way to spawning grounds in the Pamunkey and Mattaponi tributaries of the York River were fitted with acoustic tags. Movements were monitored by three hydrophone stations.
- Almost half of the tagged animals altered their migratory behavior by delaying or abandoning migration.
- Some fish spent time in both tributaries, suggesting the possibility of alternating spawning between rivers.
- Analytical models using tagging data should account for these behaviors.
Olney et al. 2006
In 2005, 98 adult shad were tagged with acoustic transmitters and released in the lower James River. Movements were monitored by nine stations covering a 121 km stretch of the river from Hog Island to just upriver of Bosher's Dam.
- Fifty percent of the tagged animals were detected upstream of the lowermost station.
- Migratory movements were significantly related to tidal cycle.
- Shad spent an average of 29 days in the spawning grounds.
- Main residence areas for American shad during the study period were Richmond Deepwater Terminal, Shirley Plantation, and Upper Brandon Plantation.
Aunins, A.W. 2006. Migratory and spawning behavior of American shad in the James River, Virginia. MS. Thesis. College of William and Mary, Gloucester Point, VA. 99 pp.
Olney, J.E., R.J. Latour, B.E. Watkins, and D.G. Clarke. 2006. Migratory behavior of American shad in the York River, Virginia, with implications for estimating in-river exploitation from tag recovery data. Transactions of the American Fisheries Society 135:889-896. Download PDF (103 KB).
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