Spawning spread of knowledge

New Web database lets managers track disease-carrying fish

Despite being scientists, biologists and animal health managers have traditionally had to rely on an unscientific method—erring on the side of caution—to decide how much to restrict potentially pathogen-carrying fish from freely moving about the country or whether to introduce fish into new habitats.

With few tools at their disposal to determine whether pathogens, organisms capable of causing disease, pose a real threat, fish resource managers usually have had to make conservative decisions when it comes to fish populations. But a new database and companion Web site, unveiled last month by the U.S. Fish and Wildlife Service (FWS), could arm managers with better pathogen information to make more scientifically sound decisions.

The National Wild Fish Health Survey (, announced Sept. 20, is the first effort to develop a national database that documents pathogens in free-ranging, or wild, fish. Until now, most pathogen knowledge has been gleaned only from captive fish in hatcheries or laboratories, according to FWS.

"Up to this point in time, managers have known hardly anything about those diseases in the wild," said Tom Bell, lead biologist on the project. "Now they're getting some data they can use to support their decisions. Now they have it right in front of them."

The project, launched in 1996 partly in response to an outbreak of an illness called Whirling disease that killed trout in Montana and Colorado, is designed to help managers determine which pathogens pose threats—and where—and keep fish populations healthy.

"Surprisingly little is known about the prevalence of pathogens among wild, free-ranging fish," said Cathleen Short, assistant director for fisheries and habitat conservation at FWS. "This survey tells us about potential threats to the well-being of America's fish populations and helps managers see that this resource remains vital and abundant."

The database and Web site, maintained by Montana State University's Environmental Statistics Group, categorizes its information via the U.S. Geological Survey's system of 2,150 catalog units. A catalog unit is the smallest watershed area represented in USGS' hydrologic unit code (HUC) system.

After submitting a query, biologists can view tables, graphs or color-coded HUC maps showing where pathogens are present, either by region or individual states.

"We can pick any combination of pathogens and any combination of fish species we've looked at and query the system," Bell said. "It has as much detailed information as even a fish pathologist would want to see."

Visitors can also click on links to Environmental Protection Agency data for any HUCs to see if patterns exist between contamination and specific pathogens, Bell said. In addition, the Web site is linked to Microsoft Corp.'s TerraServer, which enables users to view aerial photographs of the lands they are researching. Knowing whether an area is residential, for example, could have a major impact on biologists' decisions, Bell said.

"[The database is] helping us to build a better understanding as to what's going on in that particular watershed subunit," he said. "It's a phenomenal way of looking at a watershed and seeing how a pathogen might move through a watershed."

Daniel Goodman, a professor of ecology at Montana State, said seeing pathogen patterns mapped out gives biologists a new perspective.

For example, biologists can now determine whether a pathogen concentration in a particular watershed is upstream or downstream—helping them predict where it might appear next.

"I think the ability to provide access to the information in this spatially organized way is a breakthrough," Goodman said.

From the start, creating a user-friendly interface and an intuitive design for the Web page was a top priority, Bell said.

"If it wasn't something that could be readily accessible to those managers, then it wouldn't be of value," he said. "We wanted to make it not only available to us in the Fish and Wildlife Service, but to other resource managers as well."

With only 10 percent to 20 percent of the country's catalog units represented, the survey remains a work in progress, Bell said. It may be impossible to cover the entire country, but more pathogens and more locations will be added.

"We've only begun to scratch the surface" in the number of fish and geographical areas covered, he said. "We've envisioned this to be a dynamic system that we'll continually add to."