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UNDIAGNOSED DIE-OFF, FISH - USA: (MARYLAND)
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A ProMED-mail post
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International Society for Infectious Diseases
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Date: 2 Jul 2009
Source: Baltimore Sun [edited]
<http://www.baltimoresun.com/sports/outdoors/bal-fishing702,0,1165967.story>
State fisheries biologists are trying to learn what killed hundreds of
bass on the Potomac River, just days after 2 fishing tournaments.
The fish were discovered and reported Monday [29 Jun 2009] by a
fishing guide and longtime opponent of the large number of tournaments
held each year on the river near Smallwood State Park in Charles County.
Don Cosden, chief of Inland Fisheries for the Department of Natural
Resources, said biologists on the water Tuesday [30 Jun 2009]
estimated there were 600 dead bass along with several hundred catfish
and other species over a 6-mile stretch of the river.
"It's not unusual to see a number of dead catfish and gizzard shad
this time of year, and all of the bass were legal size, so we believe
that this was related to tournament releases," Cosden said. "There
were more than 3200 fish weighed in over the 3-day period, so this
would be about an 18.5 percent total mortality, which is unacceptably
high."
Cosden said his staff is in contact with officials of the tournaments
to get details. Ironically, state biologists were at the smaller of
the 2 events Saturday [27 Jun 2009] -- the one-day National Guard FLW
College Fishing tournament, which involved 80 anglers -- to measure
and tag about 100 fish for a mortality study. All of those fish
appeared healthy as the scientists handled them.
The larger event -- the 3-day FLW Stren Series -- attracted 158
anglers, but only the top 10 fished the final day.
Guide Ken Penrod, who reported the problem and wants a complete
investigation, said he has no issue with well-run events but is angry
that "most of these 100- to 200-boat events are from out of state, and
they abuse our fishery and our rights."
Cosden said most of the data on fish kills involves immediate
mortality, not 2 to 3 days after being released.
Some studies have linked poor water quality to a high degree of
delayed mortality after tournaments. But water samples taken
continuously at the docks by the Tidewater Ecosystem Assessment group
indicate temperature and dissolved oxygen levels to be within
acceptable ranges.
The state has sent tissue samples to a laboratory to be tested for
largemouth bass virus. A recent study suggested that bass heavily
infected with this virus may suffer higher release mortalities after
being confined in livewells, the aerated holding tanks on bass fishing
boats.
"Right now," said Cosden, "we don't have an answer."
[Byline: Candus Thomson <candy.thomson@baltsun.com>]
--
Communicated by:
HealthMap Alerts via
ProMED-mail <promed@promedmail.org>
[This article is sure to anger anglers, as it points a finger at them
based only on assumption. The circumstantial evidence is not even that
strong, as it is admitted that most fish die immediately, not after a
few days.
Water quality may involve more than just dissolved oxygen and
temperature. While those are parameters that fish are sensitive to,
other factors would include other chemicals in the water,
pharmaceutical agents in the water, pH of the water, and viruses and
bacteria.
Hopefully, a necropsy of some of the fish will reveal something. - Mod.TG]
[see also:
Fish die-off - USA: (VA) 20090612.2169
Drugs, fish, contaminated waterways - USA (02) 20090401.1256
Drugs, fish, contaminated waterways - USA 20090331.1246]
......................................................tg/msp/jw
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