Geographical Information Systems (GIS)
for Fish Conservation

by Karl Blankenship

Nearly 35,000 years ago, Cro-Magnon hunters drew on cave walls pictures of the animals they sought. Along with the drawings, they drew track lines that appear to depict migration routes, as well as marks that seem to be tallies of animals using those routes.

This helped the "cave men" keep track of when and where they would have the best chance of finding the greatest number of animals. Today, scientists have combined that stone age idea with high tech computers and have come up with something they call the "geographic information system"--or GIS. Increasingly, scientists and others are turning to GIS programs to help keep tabs on a wide range of important resources--like fish.

Recently, scientists at Penn State fed more than 22,000 individual fish-survey records--each identifying a particular species and where it was found--into a GIS program. The idea was to judge the status of a species based on its abundance and distribution. The result of the analysis shows that 35 percent of the state's 159 fish species are in peril. Some were even worse off: The deepwater sculpin, silver lamprey and spoonhead sculpin were all extirpated from the state.

To reach their conclusions, the scientists did what Cro-Magnons did tens of thousands of years ago. They took databases of information and combined them with graphic files to present information in a mapped, or geographical, form. On their cave walls in what is now France, the hunters used information about the kinds and numbers of animals migrating--a database--and combined it with the migration route--the geographical element.

The main difference is that today's computers allow scientists to use huge amounts of information. Before, the notion of trying to locate 22,000 individual records on stacks of paper maps was unimaginable.

"When we were manually overlaying maps, it was really laborious," said Robert Carline, a Penn State professor of fisheries science. "A lot of things we didn't even think about doing. This technology has allowed us to organize and analyze data in ways that we were never able to do in the past."

"Obviously, objective data is what is most likely to stand up in court, and it is most likely to be persuasive or convincing to a third party who may not know much about a species," said Andrew Shiels, the Fish & Boat Commission's Nongame and Endangered Species Unit Leader. "If you can keep your data as unbiased and scientifically obtained as possible, that strengthens your argument."

A GIS can display any information as long as it can be organized geographically--or mapped. But a GIS can also display lots of mapped "layers" at once, sort of like a stack of transparencies. Instead of looking at distribution information for, say, the mountain madtom, scientists can look at many layers--or species--at once. When they do, they begin to see new insights: As they looked at the fish information, for instance, it became clear that some watersheds were home to multiple rare species.

That knowledge could be used to help target programs, such as stream restoration projects, toward "hot spots" with several threatened or endangered species.

PA map


"We're able to identify watersheds with high species diversity and rank them in terms of those that really merit protection," Carline said. "That would be a valuable piece of information for decision makers, in terms of allocating public funds."

That is just the beginning. Different types of information can be added as new layers. Scientists, as part of a project supported by the Wild Resource Conservation Fund and the Fish & Boat Commission, are now putting more information about land use and geology into the program, which they hope will allow them more precisely to identify the conditions in which particular fish are found. By looking at the GIS, they could quickly see if a species is found only in, say, streams with steep slopes in oak forests with limestone geology.

Taking that a step further, they should also be able to identify where rare fish should be found--based on habitat conditions--but are absent. New monitoring efforts could begin in those areas to see if the fish are present and have merely been overlooked. That type of information could be used someday to identify potential sites where rare species could be reintroduced to rebuild and expand the population, Carline said.

Cro-Magnon's form of GIS may have helped set him apart from many other prehistoric hominids in an important respect--he survived, while many others went the way of the Neanderthal. Scientists hope the blend of his stone age concept with high tech will help today's fish and other resources survive as well.

May/June 2000 Angler & Boater

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