Pathogen stalks fish

[98Fahrenheit]

Source: The Toronto Star (http://www.thestar.com/News/article/198816)

 

Scientists urge action; shipping industry fears cost of controlling virus could be catastrophic

 

Apr 03, 2007 04:30 AM (Peter Gorrie, Environment writer)

 

Sometime this spring, Great Lakes fish could start dying by the tens of thousands.

 

It happened a few times last year: This year might be worse.

 

The killer will be viral hemorrhagic septicemia, or VHS, a virus that's a mystery except for one thing – it spreads fast and kills many types of fish.

 

The disease leaves its victims – salmon, lake trout, perch, pickerel, white bass, muskie; in fact, almost every sports and commercial species – belly-up, with bulging eyes, red splotches and bleeding organs.

 

Exactly when and how it got into the lakes isn't certain. Nor is its eventual impact.

 

"There is no way of knowing," says Gary Whelan, fish production manager in Michigan's department of natural resources. "This is a new virus in a new location, so we have no experience to guide us."

 

The deaths to date are just a small fraction of the millions of fish in the lakes. Even so, governments around the lakes are worried enough to try unprecedented steps to contain the virus.

 

VHS is suspected to be the latest on a growing list of destructive species – including zebra mussels and round gobies – brought into the lakes from Europe and Asia, usually in the ballast water of ocean-going ships.

 

The potential impact on fish isn't the only concern. VHS doesn't harm humans, but that doesn't mean others that follow will be so benign, says Jennifer Nalbone, of Great Lakes United, a cross-border advocacy group based in Buffalo that for years has demanded strict controls on ballast.

 

"It's a wake-up call that the lakes are vulnerable to any pathogen getting in here. We need to try to slow the spread but also to close the door."

 

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Initial reports said VHS was detected in the Bay of Quinte in 2005 by John Lumsden, a fish health specialist at the University of Guelph. The first big die-offs it's blamed for came last year.

 

New evidence suggests it's been in the lakes a few years longer, Lumsden says. In any case, in a short time it has infected all except Superior.

 

The virus is an Atlantic Ocean strain of VHS, one of four main varieties around the globe. Like the other invaders that gain a foothold, it can't be stopped.

 

Provincial and state scientists just want to slow it down. The control effort is creating conflict with fish hatcheries, anglers' groups and, especially, ship owners. Companies that sail only within the Great Lakes warn some proposed solutions could put them out of business.

 

Still, the cost of not acting would be much higher, says Whelan. "We can't wait forever. The amount of damage being done is incalculable. Everyone has to play their part."

 

Ontario's ministry of natural resources is so concerned about infected fish swimming into inland waters that a couple of weeks ago it tried to prevent salmon and other species from swimming up rivers to spawn. It closed the fishways that let them pass barriers such as dams. It also made it illegal for humans to help fish over impediments, a common springtime practice.

 

The measure would have stopped most fish reproduction on 18 major rivers, including the Credit, west of Toronto, and the Ganaraska, to the east.

 

"We're just trying to give ourselves some time to get a handle on where the virus is," John Cooper, spokesperson for the ministry's Lake Erie Management Unit, in London, said while the order was in place. "We're trying to keep it confined to the lower Great Lakes as long as possible."

 

But late last week, Natural Resources Minister David Ramsay announced the fishways could reopen.

 

The Ontario Federation of Anglers and Hunters and other fishing groups had strongly opposed the closing, and the scientific evidence wasn't strong enough to justify shutting down spring fishing activities, Cooper says.

 

"We don't know enough at this point," he says. "If the science was clear, the fishways would have been closed."

 

Instead, the province – like many American states and the U.S. government – has slapped restrictions on moving fish, minnows and other live bait, and fish eggs from infected to uninfected areas.

 

The U.S. recently banned carrying fish across state and international borders, even when the boundaries run through infected water. That's put a crimp on big-prize fishing tournaments and, again, the government is under pressure to back down.

 

Some experts argue the only way to stop invaders is with tough restrictions on ships – both ocean ships and those that operate only on the Great Lakes. Attempts to control the movement of infected fish is just part of the solution, Nalbone says. "You don't solve the problem by dealing with half of it."

 

The unwanted creatures generally arrive in ballast water, which ships carry to stay stable when not carrying cargo. It's dumped when they pick up loads.

 

Once invaders are in the lakes, local ships spread them around.

 

Whelan and many others say the only answer is to require all ships to disinfect their ballast water.

 

The cost would be catastrophic, particularly for domestic ships, says Jim Weakly, president of the Lake Carriers' Association, which represents American lakers. And that, he suggests, brings a different threat: "You have to take into account the economic importance of the lakers, and the cost of treating the ballast ... and you need to ask what the benefit would be."

 

The shippers are already putting screens over the pipes that carry ballast in and out of their tanks, he says. They're also using their pumps full force, to pulverize fish that do make it through the screen.

 

But among the many things not known about VHS is how long it survives after its fish host is killed, or in open water. If it lasts a few days, it could still be spread in fish bits.

 

Industries always react that way to new regulations, says Whelan.

 

"The reality is that we have billions of dollars worth of damage to the fishery and it's high time they did something."

 

As for exactly what will happen this summer, and beyond, that's another uncertainty, Lumsden says: "2006 was probably just the start. This may go on for several years."

 

Eventually, fish might adapt to the virus, letting it recede into the background, he says. Even then, "it may not be a good one."

Edited April 3, 2007 by 98Fahrenheit

[Jeff O]

Please note that at the 2007 Muskie Odyssey, April 14th, we will have Dr. John M. Casselman, retired OMNR Biologist, and Ph.D., Adjunct Professor

Queen's University, Department of Biology speaking on this very timely topic. John is one of North America's leading experts in this area and he will discuss VHS and its impact.

 

Please see http://www.youtube.com/watch?v=8D3OXy9uo1k and http://www.muskiescanada.ca/ for more information about the Odyssey.

 

 

See you at the show!