After recording the fourth highest results for the Maryland striped bass juvenile index last year, 2012 will go down on record as being the worst in the 59-year history of the study with an index of only 0.9. The striped bass juvenile index is a measure of striped bass spawning success in the Chesapeake Bay and has traditionally been used as a tool to assist in gauging the health of the stock along the Atlantic coast.
According to Maryland Department of Natural Resources (MD DNR) fisheries director Tom O’Connell, “While we expect large variation in striped bass reproduction from year to year and do not view this low value as an imminent problem, we will be carefully monitoring the results of future surveys. Three consecutive years of poor reproduction would be necessary to trigger mandatory conservation measures.”
Year to year, the findings are expected to vary based on environmental factors such as water temperature and flow rates in the spawning grounds, as well as spawning population size and age-class make up of available fish. Traditionally it has been found that the year immediately following a banner year falls well below average. This was the case in the top three years of 1989, 1996 and 2001 as each were followed by less than average success rates.
%pullstart%“Generally, warm winters and dry springs are unfavorable conditions for fish that return to freshwater to spawn,” said DNR Striped Bass Survey Project Leader Eric Durell. This is exactly what was experienced in the winter and spring of 2012.%pullend%Poor findings were not limited to striped bass in 2012 as other anadromous species such as white perch, yellow perch and river herring also tallied low reproductive success. This leads to the likelihood of the low success rate in striped bass being affected more by environmental influences than other factors.
“Generally, warm winters and dry springs are unfavorable conditions for fish that return to freshwater to spawn,” said DNR Striped Bass Survey Project Leader Eric Durell. This is exactly what was experienced in the winter and spring of 2012.
The 2012 sampling included over 31,000 specimens encompassing 54 species. The survey was conducted over 22 locations that included the four primary striped bass spawning systems of the Choptank, Potomac and Nanticoke rivers, and the Upper Chesapeake Bay. The survey was conducted between July and September. Two samples were taken at each location per outing as a 100-foot seine was swept through prime habitat. The catch was then identified and cataloged and the findings were noted as the average young of the year (YOY) caught per seine. Therefore this year’s figure of 0.9 indicates that each seine found, on average, less than one YOY striped bass per haul. While this is not immediate cause for concern, we eagerly await the findings in 2013 and 2014 to see if the down-trend continues or if this was simply an isolated event.
