Estimation of juvenile striped bass relative abundance in the Virginia portion of Chesapeake Bay, January 2012-December 2012 : annual progress report
Virginia Institute of Marine Science
The 2012 Striped Bass juvenile abundance index is 2.68 and is significantly lower than the historic average of 6.96. Recruitment failure, as defined by Addendum II to Amendment 6 of the FMP, occurred during 2012. All individual watershed JAI values were below their historic mean. The Rappahannock, Pamunkey and Chickahominy River JAI values were significantly lower than their respective historic averages. Although lower JAI values were reported for the James and Mattaponi rivers, annual JAI confidence intervals overlapped with historic confidence intervals suggesting juvenile abundance in these two rivers was not significantly different from the longterm average abundance. Based on our sampling of auxiliary stations juvenile Striped Bass generally did not occupy sites outside of the core nursery zone during 2012.
Pilot sampling prior to the 2012 field season revealed that juvenile Striped Bass and White Perch of the size commonly encountered in early July were available to the seine in early June. Therefore, seine survey sampling commenced one week earlier than the traditional start period to ensure sampling of similar sized individuals. The historic average is now properly reported as the geometric mean of annual juvenile abundance estimates in this report and that for 2011. Previous to 2011, the historic average was calculated as the mean abundance across all stations sampled over all years; this method effectively weighted the mean by the number of stations sampled in any given year, and because the survey sampled fewer stations prior to 1988, positively biased the historic mean towards recent abundance estimates. A JAI has been provided for Atlantic Croaker for 2012. Also new to the 2012 report is the use of the revised naming convention for common names of fishes recently adopted by the American Fisheries Society and the American Society of Ichthyologists and Herpetologists.
Striped bass -- Chesapeake Bay (Md. and Va.); Striped bass fisheries -- Chesapeake Bay (Md. and Va.)
Machut, L. S., & Fabrizio, M. C. (2013) Estimation of juvenile striped bass relative abundance in the Virginia portion of Chesapeake Bay, January 2012-December 2012 : annual progress report. Virginia Institute of Marine Science, William & Mary. http://dx.doi.org/doi:10.21220/m2-z9sb-zj55