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The mystery of shad's dwindling numbers
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JEF DAUBER/Courier-Post |
By LAWRENCE R. HAJNA
Courier-Post Staff
Shad, a popular game fish along the entire Delaware River, has been known as the river's poster child, its virtual disappearance serving as a rallying cry for cleanup.
It appears shad are in trouble once again, but this time scientists are not sure what's going on.
Monitors at Lambertville have tracked between 300,000 and 500,000 shad coming up river in recent years, peaking at nearly 800,000 in 1996. This spring, the number has plummeted to about 30,000...comparable to pre-cleanup numbers.
"The drop is so dramatic, it's unbelievable," said Robert Soldwedel, chief of New Jersey's Bureau of Freshwater Fisheries. "A lot of people went to their favorite fishing holes and didn't get anything."
While researchers are baffled, they don't suspect pollution. Other pollution-sensitive fish...including striped bass...are doing well, Soldwedel said. A combination of factors may be at work with regard to shad, including decreased water flows and hotter water temperatures that may have reduced the spring migration up river, increased predation by striped bass and increased commercial harvesting.
"There's a lot of theories out there, but the truth is we may never be able to tie this down to any single factor," Soldwedel said.
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