11
Okt
2005

What's killing our fish?

*Experts fear a 'perfect storm' of factors*

Tuesday, October 11, 2005
BY BRETT LIEBERMAN
*Of Our Washington Bureau*

http://www.pennlive.com/news/patriotnews/index.ssf?/base/news/1129022557316680.xml

WASHINGTON - The thousands of smallmouth bass that died this summer in central Pennsylvania rivers might be part of a broader national problem that's being spurred by pollution, climate change and even hormones such as birth control pills taken by humans.

Researchers, environmentalists, and fish and wildlife experts worry that these environmental effects are creating a "perfect storm" that is beginning to cripple aquatic ecosystems and could be a warning of looming problems for all species.

"We started covering this because scientists working on specific fish kills kept referring to a strange new problem sweeping the country," said Jay Gourley, the vice president of the nonprofit Public Education Center, which tracks environmental issues and is calling attention to the spreading problem.

The group has documented cases from California to New York that are similar to the one that left thousands of bass floating in the Susquehanna River in July.

"They were frantic to explain how various harmful factors, not necessarily catastrophic by themselves, were combining into one perfect storm after another and wiping out aquatic ecosystems at a frightening pace," Gourley said.

Low water flows, higher water temperatures, low oxygen levels in the water and lesions on thousands of smallmouth bass contributed to the fish kill in the Susquehanna and Juniata rivers from Sunbury to south of Harrisburg. But fish and environmental experts said they appear to be only part of the cause of July's kill.

"I think a lot of our river systems are seeing multiple stresses that are affecting fish species," said Betsy Otto, a senior director of river advocacy for American Rivers, which named the Susquehanna the nation's most endangered river this year.

"This is becoming a more widespread problem, and it's likely to become worse," she said.

"At this point, there's not any science to say we know what caused this," said Paul O. Swartz, the executive director of the Susquehanna River Basin Commission. "It's really circumstantial evidence, and it's really tough to understand."

* Combination of stressors:*

The river commission is assisting the Pennsylvania Fish and Boat Commission and other agencies investigating large and unexplained fish kills in the lower Susquehanna and at least 20 other bodies of water.

Low water levels contributed to warmer water temperatures, and a lack of grasses on the river bottom meant less oxygen was being produced. The warmer temperatures led to higher levels of bacteria, including columnaris, a common bacterium that usually does not affect fish.

Those factors alone likely did not cause the fish kill but probably weakened their ability to fight the bacteria.

"The fish were stressed and immunosuppressed, and they would probably be susceptible to a variety of opportunistic pathogens," said Vicki Blazer, a fish pathologist for the U.S. Geological Survey who has been investigating unexplained and large fish kills on the Shenandoah and Potomac rivers.

"You're dealing with a multitude of things that are not, in and of themselves, enough to cause death, but they push animals beyond their physiological limits," USGS immunologist Chris Ottinger said in a statement.

Many fish are dying from diseases that are not normally fatal, said Ottinger, who is studying an epidemic of fish tuberculosis downstream from the Susquehanna in the Chesapeake Bay.

* 'A scary decline':*

Studying similar fish kills in the Shenandoah and Potomac, Blazer found microscopic evidence of intersex, the exposure to endocrine-disrupting chemicals that lead male fish to grow eggs.

She said the change demonstrates the impact of slow exposure to estrogenic compounds found in agricultural runoff and human waste downstream from sewage treatment plants.

Most water and environmental testing monitors exposure to cancer-causing PCBs, mercury and similar chemicals.

European countries have been studying the impact of synthetic hormones frequently used by humans for hormone-replacement treatment or birth control and then excreted. Researchers in the United States are just beginning to investigate their effects.

"These particular type of chemicals work at such low levels," Blazer said.

Dan Tredinnick, a spokesman for the Pennsylvania Fish and Boat Commission, said researchers are plowing through mounds of data without answers.

"There isn't any one single piece of data or one single thing that leaps out," he said, adding, "We have been in contact with fellow state agencies trying to pick their brains."

The only completed research is an analysis of smallmouth bass birth rates during the past 18 years that shows many young fish last spring.

Large numbers of "young of the year" might be a good indicator of the species' future health, though several area anglers said the number of fish caught has dropped sharply during the past 20 years.

"The overall population of most of the fish are way down," said Bob Clouser of Middletown, a fisherman and river guide.

Clouser used to be able to take two experienced anglers out for a day on the Susquehanna and expect to catch about 50 fish each. Now they're lucky to catch eight.

"It's a scary decline," he said, adding that he's watched as water snakes, bull frogs and then other species have disappeared. "I don't know what it's all related to, but I assume it's some sort of pollution."

Clouser is sure of one thing: that the Susquehanna's waters have grown heavier and darker than when he started fishing on its banks.

BRETT LIEBERMAN: (202) 383-7833 or blieberman@patriot-news.com

*FISH KILLS*

Recent large fish kills that fit the "perfect storm" pattern. Source: The Public Education Center

# JULY, Susquehanna and Juniata rivers: Many smallmouth bass, from Sunbury to south of Harrisburg, died in a kill attributed to an outbreak of a bacterial infection, columnaris. The cause of the outbreak is unknown.

# 2005, Chesapeake Bay: As many as 70 percent of bay rockfish are infected with mycobacteriosis, or "fish tuberculosis." The number has risen from
11 percent in 1997. Many scientists attribute the increase to a "perfect storm" of poor nutrition, excess nitrogen, warm temperatures and low oxygen.

# 2005, Shenandoah River, south fork and main, Va.: An estimated 80 percent of smallmouth bass died, and bacterial lesions were classified as a "secondary" effect caused by an unknown stressor.

# 1999-2005, Long Island Sound, N.Y.: In the past three years, about 95 percent of the basin's lobster stock has died. Lobsters in the eastern sound have been suffering from "shell disease," a bacterial infection that has greatly increased in recent years. Scientists say a "perfect storm" that caused a population crash in 1999 has not abated.

© 2005 The Patriot-News
© 2005 PennLive.com


Informant: Teresa Binstock
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