This article came from the Baltimore Sun:

Potomac River, tournament related bass kill: one hundred and fifty-eight boats (316 anglers), launching boats from Smallwood State Park on June 25 and 26 and left behind a conservatively estimated 1000 largemouth bass, floating in the river, a disgraceful and unforgivable result. Maryland Department of Natural Resources initially estimated the kill to be 100. I began to contact DNR on Tuesday, June 30 after receiving many telephone calls from concerned anglers. I asked for an immediate investigation and on Wednesday, July 1, a team of DNR employees searched the creek and by their count, some 600 dead bass were still in Mattawoman Creek. That's four days (about seven tidal flushes) after the last day of the tournament. There is no way to estimate accurately how many bass died due to this event-but I firmly believe that "600" is just the tip of the iceberg. I have reliable reports from as far downriver as Arkindale Flats of huge amounts of dead bass days after the event.

State fisheries biologists are trying to learn what killed hundreds of bass on the Potomac River, just days after two fishing tournaments.

The fish were discovered and reported Monday 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 estimated there were 600 dead bass along with several hundred catfish and other species over a six-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 3,200 fish weighed in over the three-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 two events Saturday -- 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 three-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 two to three 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."

Hundreds of bass found dead on Potomac

State investigating after 600 discovered, along with hundreds of other dead fish, after recent fishing tournaments in Charles County By Candus Thomson- The Baltimore Sun

State fisheries biologists are trying to learn what killed hundreds of bass on the Potomac River, just days after two fishing tournaments.

The fish were discovered and reported Monday 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 estimated there were 600 dead bass along with several hundred catfish and other species over a six-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 3,200 fish weighed in over the three-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 two events Saturday -- 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 three-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 two to three 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."

Did you hear? CO2 makes fish ears bigger

Unexpected finding could have implications for climate change debate

By Randolph E. Schmid- The Associated Press

WASHINGTON - Listen up! Carbon dioxide being absorbed by the oceans is having a puzzling effect on fish - their ears get bigger.

Now, that doesn't mean you're going to reel in the Mr. Spock of the sea. Fish ears are inside their bodies.

But, as in humans, their ears perform a major role in sensing movement and whether the animal is upright - abilities that are important for survival.

"It was a surprise," biological oceanographer David M. Checkley of the Scripps Institution of Oceanography at the University of California at San Diego said of the discovery. "The assumption is that anything that departs significantly from normality is an abnormality, and abnormalities at least have the potential for having deleterious effects."

The ear structure in fish is known as an otolith and is made up of minerals. Checkley and colleagues knew that increasing carbon dioxide in the oceans - absorbed from the atmosphere - is making the sea more acidic, which can dissolve and weaken shells. They wondered if it also would reduce the size of the otoliths.

Just the opposite, it turned out, the researchers report in Friday's edition of the journal Science.

In their experiment they incubated the eggs of white sea bass in seawater and measured the otoliths when the fish were 7 to 8 days old.

In the first test, the water had more than six times the current amount of carbon dioxide, and the little fish grew otoliths 15 percent to 17 percent larger than normal. The researchers were so surprised they repeated the experiment, and got the same results.

So they reduced the carbon dioxide in the water to about 3.5 times the current level - a concentration that could occur by the year 2100 at the rate CO2 is being added to the atmosphere and then the sea. Those fish had ear bones 7 percent to 9 percent larger than fish raised in seawater with current gas concentrations.

"An important observation is that the effect of CO2 in atmosphere, and therefore in the ocean, includes not only (global) warming and making the ocean more acidic. There are other effects on the biology and ecology that merit study," Checkley said in a telephone interview.

The new finding, surprising in itself, raises further questions Checkley said need to be explored.

Researchers now will try to figure out how the added carbon dioxide in the water causes the ear bones to enlarge, whether this is happening to other types of fish, and whether the long-term effect will be good or bad.

"If fish can do just fine or better with larger otoliths, then there's no great concern. But fish have evolved to have their bodies the way they are. The assumption is that if you tweak them in a certain way it's going to change the dynamics of how the otolith helps the fish stay upright, navigate and survive," Checkley said.

There are anecdotal observations that fish in higher concentrations of CO2 seem to be lethargic, he added, but that needs confirmation.

"Don Cosden, chief of Inland Fisheries for the Department of Natural Resources, said biologists on the water Tuesday estimated there were 600 dead bass along with several hundred catfish and other species over a six-mile stretch of the river."

I find it quite curious that a tournament for bass could cause the demise of hundreds of catfish and other species. Someone needs to look for another cause for the fish kill. It doesn't sound like an O2 problem as cat fish are are quite adept at breathing air.

Don Cosdoen said that the dead catfish at this time of year is normal for the river, his quote is below.  I really hope the biologists figure out what happened and I hope it was not related to the Stren tournament.

Don Cosden, chief of Inland Fisheries for the Department of Natural Resources, said biologists on the water Tuesday estimated there were 600 dead bass along with several hundred catfish and other species over a six-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 3,200 fish weighed in over the three-day period, so this would be about an 18.5 percent total mortality, which is unacceptably high."

Wow, hundreds of dead cat fish is normal? Strange.  All of the bass being legal size is strange too.  Keep us updated!

When we were out the other day we must have seen about a dozen dead catfish.

Awful.

Sorry the loss was not about 15 miles to the northwest in a big building with a dome on it.