Agricultural Sciences

River Otters, Fishers Now Firmly Established In Pennsylvania

UNIVERSITY PARK, Pa. -- Nearly 20 years after the first river otter was reintroduced into Pennsylvania waterways, the joint project -- a collaboration between Penn State and other universities, the Pennsylvania Game Commission, the Wild Resource Conservation Fund and the Allegheny National Forest -- stands out as a highlight in the history of wildlife management in the commonwealth.

The reestablishment of the otter population and a related repopulation of another carnivorous but not water-loving weasel, the fisher, rank with the comeback of the elk, the recovery of the white-tailed deer herd, the arrival of the coyote and the reemergence of birds of prey as the most significant wildlife developments of the century in Pennsylvania.

Over the last 19 years, approximately 125 otters and 190 fishers were released into sparsely populated, densely forested, mostly publicly owned areas in the northern part of the state. According to Robert Brooks, professor of wildlife and wetlands, most of the animals survived, some have reproduced and both populations are expanding. In areas where they are numerous, the animals occasionally are seen and their sign is not uncommon.

"The reintroduction of otters and fishers was so successful because the weasels are top level carnivores not perceived to be dangerous to humans like wolves and cougars," says Brooks. "River otters were a natural because of their playful nature. When that program was successful, it was just logical to reintroduce fishers."

Both river otters and fishers were extirpated from most of Pennsylvania by the early 1900s, victims of unregulated trapping, cutting of huge tracts of dense forest and destructive mining practices. Water pollution and siltation may have played a part in the otter's demise.

Most of the reintroduced animals were captured in northern New York and New Hampshire and shipped here in special containers.

Fishers, which don't normally eat fish at all, often prey on porcupines, neatly turning them over to escape the quills and get at their vulnerable bellies. They avoid water, but trappers found them easy quarry because of their ultra-curious nature and trappers commonly baited their traps with fish -- hence the name fisher.

"These are very wide-ranging, elusive, often solitary animals and therefore accurate population estimates are difficult to come up with," says Brooks. "But we have seen range expansion for both species. We have seen evidence of reproduction. We had very little reported mortality.

"The animals' survivorship here was higher than in other states where they have been reintroduced because of the care taken in handling the animals and selecting the best reintroduction sites."

Radio collar monitoring and remotely activated cameras have shown how well the otters and fishers are doing.

"Pennsylvania's habitat has been improved and we have a system of private and public lands -- streams, wetlands and mature forests -- to support both carnivores," says Brooks. "You couldn't do this, for example, in Ohio."

Tom Serfass, now an assistant professor of wildlife ecology at Frostburg State University in western Maryland, earned his Ph.D. at Penn State managing the otter-fisher project. For him, just stocking the weasels was not enough.

"We felt very confident that there was enough habitat for them," he says. "We didn't want just a novelty. Our goal was to establish a population that had the long-term potential to persist and expand. And that is happening."

But pleased as he is about the animals' reaction to living in Pennsylvania, Serfass is perhaps most gratified by peoples' reaction to the animals residing here.

"It is the human dimension associated with these projects that is so satisfying," he says. "When you introduce animals, you need public support. If you tried to introduce predators like this in the early 1900s, you would have encountered stiff opposition.

"Maybe we have rounded the corner in terms of attitudes towards these animals, and maybe through these projects we have educated the public," Serfass adds. "Wildlife biologists don't work in isolation."

Brooks recalls very little resistance to the reintroductions, mostly unbridled enthusiasm.

"Initially some people worried about weasels attacking their pets and a few fishermen were concerned about otters eating trout," he remembers. "We had to persuade people that river otters primarily eat soft-rayed fish such as suckers. But there were few problems. The releases were publicized and the public came out to watch -- they were quite festive occasions."

Serfass notes that the presence of the weasels has boosted tourism in places across the Northern Tier of Pennsylvania, a welcome development in an economically depressed region.

"Everyone talks about going to see the elk," he says, "but some folks go to Pine Creek Valley just to see the river otters."


EDITORS: Rob Brooks can be contacted at 814-863-1596; Tom Serfass at (301) 687-4171.

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Jeff Mulhollem 814-863-2719 814-865-1068 fax

Last Updated March 19, 2009