New Coaster Brook Trout Monitoring Stations on Isle Royale
BY ANNA VARIAN, ASHLAND FWCO
Late this summer, Ashland Fish and Wildlife Conservation Office (FWCO) fish biologists, Henry Quinlan and Anna Varian, set out across Lake Superior to Isle Royale National Park to construct the second and third coaster brook trout monitoring stations on the Island. Through a partnership between Isle Royale National Park and the Ashland FWCO the materials used to construct the stations were acquired through a National Park Service (NPS) grant. Station design and layout was done by U.S. Fish and Wildlife Service fish biologist Glenn Miller and technician Tyler Sikora, and station set-up was completed by Henry and Anna. Station upkeep will be conducted jointly by the Ashland FWCO and NPS.
Historically large coaster brook trout were caught up and down the Lake Superior shoreline, but overfishing and land-use changes have decimated their populations. Isle Royale is one of the few locations in the United States that has been able to support historic coaster brook trout populations. The Salmon Trout River in Michigan also supports a historic coaster population, as do rivers in Pictured Rocks National Lakeshore and several streams along the north shore of Minnesota. All show evidence of coaster brook trout presence since new regulations and rehabilitation efforts were put into effect.
Mid-construction of the station at the Siskiwit River. Solar panels positioned vertically may receive less sun then those slightly angled toward the sun, but a vertical position prevents snow from accumulating during the long winter months when the island is uninhabited and blocking out the sun altogether. Credit: Anna Varian, USFWS
Monitoring stations are designed to detect movement of passive integrated transponder (PIT) tagged fish in and out of a stream, and help biologists learn more about the habits of coaster brook trout. In 2008, the first station was set up on Washington Creek on the southwest end of the island. Since then, over 300 brook trout, both stream dwelling and coasters, have been tagged and released, and more than half of the tagged fish have been detected moving upstream or downstream past the antenna.
Each station consists of two solar panels for power, a bank of batteries, two looped wire antennas, antenna tuners, and a small computer that records the date, time, and tag number of each tagged fish as it swims past the antenna set up across the width of the stream. Two antennas are set-up near the mouth of the river at each station to allow biologists to determine the direction of fish movement (based on which antenna the fish passes first).
Credit: Anna Varian, USFWS
The new stations were set up on Benson creek near Daisy Farm campground, and on the Siskiwit River near Malone Bay campground. After set-up was complete both streams were sampled using backpack electrofishing units. Benson creek is a small creek that can dry up during drought years, yet six different species of fish were sampled in the stream. The Siskiwit River flows a short distance from Siskiwit Lake to Lake Superior and five species of fish were sampled. Brook trout have been captured in each stream in prior years during fish surveys conducted by Ashland FWCO biologists.
While the Washington Creek station is well off any maintained trail and out of sight of most visitors, the new stations are both near campgrounds. The Benson Creek station in particular is near a campground that sees many visitors; this more prominent site provides us a great opportunity for public outreach. Next summer outreach materials will be posted at the station giving visitors information on how the station works, the number of fish tagged in the stream, the species that inhabit the stream, and coaster brook trout life history information.