Studies by the Maryland Department of Natural Resources show a steady decline in reproductive success of striped bass over the last decade and a dramatic drop in the last two years.
What is the cause of this decline?
Pete Jensen, tidal fisheries director, offered the state's view. "What we see happening to striped bass is happening to the whole anadramous group of fishes," he said.
"We're seeing declines in shad, herring and perch. Reproduction and harvest are both on the decline."
Anadramous fishes are ones that live in salt or brackish water and return to freshwater rivers to spawn. Scientists believe they are suffering from the effects of changes in the rivers.
"We believe one problem is the flow in the Susquehanna River (the bay's main tributary) as affected by Conowingo Dam," Jensen said. The dam, which powers electrical turbines, often stops the river flow for long periods, stagnating the water in the prime spawning grounds below. Also, Jensen said, a fishway is needed at the dam, providing access so fish can get above it.
"Chlorine may be implicated," he said, noting that tremendous amounts of this biocide are introduced into river water at sewage-treatment plant outfalls. Frequently these outfalls are at spawning areas, and the chlorine may be killing eggs and baby stripers as well as germs.
Other possible factors: the decline of eel grasses, which once sheltered juvenile stripers and other marine life, silt from rivers in developed or farming areas; overfishing when fish populations reach critical low levels.
The chlorine problem is one that only recently has gained credence among marine scientists. For generations, the public squawked about smelly rivers, but most of that has ended with the great cleanup begun by President Johnson.
Now biologists are wondering if crystal clear, sewage-treated water is more dangerous to fish than foul water heavy with nutrients.
Jensen said the State Department of Natural Resources has reached accord with the Health Department on a program of on-site testing and modification to reduce chlorine flow from sewage-treatment plants around the Bay