Friday, July 31, 2015

The Brookies of Cap Creek

“Stick a toe in the water,” dared WDNR Fisheries Biologist Max Wolter with a sly grin. The teenage boys (and one mom) that had joined me on this adventure hesitated for only a second before taking the dare. “Wow, that’s cold,” was the general response. We’d just dipped our feet into Cap Creek, a spring-fed tributary of the upper Namekagon River, and that cold water was part of what drew us here. The cold water is also what draws native brook trout here, and this little stream hosts one of the best brook trout habitats on the Namekagon.

Every year the WDNR collects data on the number and size of trout in this stream. They accomplish this not through the elegant casting of a fly rod like we learned about a few weeks ago, but with wands that send currents of electricity through zipping the water, and nets to scoop the temporarily stunned fish up from the bottom (they don’t float when stunned as many people think). Fish shocking is a common research technique—and one that holds quite a bit of intrigue for kids of all ages.

When we’d arrived at the Cap Creek Landing on the Namekagon River, the three DNR biologists were sitting at the landing with their little research boat, counting and measuring fish. Max looked up apologetically, saying “This might take a while; we just caught an unusually high number of trout in our first sweep.” So we stood there watching and listening as two biologists pulled fingerling trout out of their nets, dropped them one at a time into measuring troughs, and called out lengths to Max, who recorded the numbers on his data sheet. While a bit tedious, this was the reality of science in action.

Things got more exciting when Max brought out a small aquarium on a tall pole. He sunk the pole in the sand, and then grabbed good-sized brook trout out of a net. Now at eye level, we could admire the beauty of this incredible fish – the only truly native trout on the Namekagon. A pattern of yellow and olive-green markings was overlain by scattered red spots, each with a halo of pale blue. The pectoral fins were a lovely shade of orange. I don’t think I’ve ever seen a more beautiful fish.

According to Max, they usually only find a dozen or so trout in this section of the Namekagon River, just below the mouth of Cap Creek. Today, they found close to a hundred. Of course we asked why. “The mild winter, he replied immediately. “All the little ones survive the winter better when it’s short and there’s not as much ice buildup.” He continued, “It’s neat to have long term data because you can look at how the weather impacts trout,” said Max. “In all the really long winters we had bad trout numbers. In all the short winters we had good numbers. You can start to see patterns.”

Of course, it’s not just the length of our winters that affects trout populations on the Namekagon and its tributaries. “Trout are fragile,” remarked Max. “They need cold, pure water, good habitat, and few contaminants.” In the old days, the Namekagon River provided all of that. Way back in 1831, the explorer Henry Schoolcraft noted the abundance of brook trout in the Namekagon River, even in the warm summer months. Later, in 1883, as tourism became a local industry, one fly-fisherman claimed that “All trout streams in the state must yield the banner to the noble and lordly Namakagon.”

The logging boom of the late 1800s and early 1900s changed that. With the large trees felled off its banks, sunlight warmed the river. Extra sediment washed into the channel and covered up some of the cold water springs that used to moderate the river’s temperature. Woody debris that previously provided cover was removed from the channel. Logging dams pooled water and allowed it to heat up before flowing downstream. None of those changes are good for a fish that can’t survive in water above sixty-eight degrees.

Cap Creek had its own set of challenges. In the 1950s, a trout farm diverted the water of this spring-fed stream into several excavated ponds. Although trout thrived in the hatchery, no native fish frequented the creek. In 1988, the National Park Service acquired the trout hatchery and began major restoration work. Cap Creek was restored to its original channel. Extra sediment was removed, revealing groundwater springs which today we watched bubbling up from the sand. They help keep the stream at a steady fifty degrees all year round. Logs were placed in the channel to provide cover and shade for the fish. “They work, too,” said Max, pointing to one of the logs along the bank, “we got seven or eight adult trout out of that spot when we came through with the nets.” He continued, “This is a great example of what you can to do restore something.”

Native prairie plants higher on the bank swayed in the breeze. They were part of the restoration, too. But all along the water’s edge were carpets of forget-me-nots, a European species that has escaped and spread along many stream banks. I commented on it being an invasive. “Well,” spoke up one of the biologists, “invasive or not, it’s good cover. That’s where all little fish are hiding when we came through.” “Plus it sure is pretty,’ noted one of the boys.

There’s another introduced species here, too, that may not be so bad. European brown trout were stocked here starting around 1883. They do better in warmer water, and frequent the main river channel more than the chilly waters of Cap Creek. The researchers only caught a few brown trout on their sweep up the creek.

By some accounts, brown trout eat the young brookies, and push them out. But with the changes in water temperature brought about by logging, and the uncertain future of climate change (which predicts our temperatures in northwestern Wisconsin to be more like eastern Kansas by the year 2095), brown trout may have a role to play in the ecosystem, especially outside areas like Cap Creek where the brookies thrive in water too cold for the browns. The interagency Fisheries Management Plan for the Namekagon and St. Croix Rivers describes the introduced brown trout as “an ecological surrogate for brook trout” and states that “brown trout are now a keystone species, maintaining the basic biological integrity of this fish community.”

Sticking our toes in the chilly stream today, we touched just a bit of a common current that runs through the history of North America. From abundance to exploitation; habitat loss to restoration; and now the preparation for an uncertain future…It is sure to be an upstream battle to conserve and create a world we – and the trout – will like living in.

Brook trout are members of the char subgroup of the salmon family. Char typically have a dark base color with light spots in contrast to true trout (like brown trout), who have light base colors and dark spots. 
Photo by Emily Stone.

DNR fisheries biologists led by Max Wolter (left), pull their boat with the electrical equipment in it upstream. Waders protect the men from the electricity that emanates from their wands. Temporarily stunned fish are scooped up with the nets and dumped into a bucket on the boat until their data can be collected. Photo by Emily Stone.

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