|Yellow Perch from Wicomico River|
Scientists have found reproductive abnormalities in yellow perch in three Maryland rivers that are either heavily suburbanized or rapidly developing, which they say helps explain why the distinctive black-striped fish are not thriving in those Chesapeake Bay tributaries and may be linked to toxic pollution.
Yellow Perch have been largely eliminated from many tributaries in the upper Bay area where they used to thrive. Yellow Perch in the Chespeake Bay occupy an unusal habitat compared to their populations across the Northern US and Canada. Most populations of Yellow Perch live in lakes and slow rivers, and run into small tributaries to spawn. Chesapeake Bay Yellow Perch live in the upper end of the Bay and tidal tributaries where salinities are relatively low, and run up into the small fresh water tributaries. It is thought this may have resulted from their migration up the Bay as the Bay re-formed after the last ice-age maximum.
Significant numbers of eggs produced by spawning female perch in the Severn and South rivers in Anne Arundel County and in Mattawoman Creek in Charles County failed to develop completely, according to a three-year survey conducted by federal and state researchers. Male perch in those rivers also displayed more abnormalities than did their counterparts from two mostly rural rivers in the upper bay.
The findings are "strongly suggestive of contaminant problems," said Jim Uphoff, a biologist with the Maryland Department of Natural Resources. Although no specific pollutant has been identified, he and other researchers say they suspect the abnormalities may stem from exposure to pharmaceuticals, heavy metals or polychlorinated biphenyls, a group of toxic chemicals once widely used in electrical equipment...
The scientists collected water and fish tissue samples, but the analysis of those has yet to be completed, so it's not clear if any particular contaminants were present. While cold weather and heavy rainfall during spawning season also can influence reproduction, the researchers say they don't believe those explain the problems they're seeing. Blazer said other studies suggest that the abnormalities in the fish may be caused by exposure to contaminants, including PCBs, metals and pharmaceuticals.So what are you waiting for?
What will they do when it turns out the sex problems are due to hormones from birth control pills that are going right through the municipal sewage systems. Ban birth control pill or municipal sewage systems?
whooooaaaah there little cowpoke. I'm still working on the rockfish tragedy. One problem at a time,ReplyDelete