In theory, put-and-take fish management is a simple process: The state Game, Fish & Parks Department puts fish in public waters and anglers take them out.
But there’s a problem, at least as it applies to rainbow trout stocked in Black Hills lakes: There’s a lot more putting than taking going on.
That matters in the Black Hills, where hatchery reared rainbow trout provide the bulk of angling action in lakes.
“The goal is we stock fish and in a certain amount of time they are harvested,” says Jake Davis, area fisheries supervisor for GF&P in Rapid City. “We know how many fish were stocked. And right now there’s really a small proportion of our hatchery fish that are being harvested by anglers.”
So what happens to the rest? That’s what a two-year study that began this year on two small lakes — Dalton and Horse Thief — is designed to find out. The project is a cooperative research venture between GF&P and South Dakota State University coordinated by Kelsen Young, an SDSU graduate student in fisheries and wildlife.
I happened upon Young out at Dalton Lake last month. I was coming down from an unsuccessful ruffed grouse hunt in the aspen and he was waiting in the parking lot of the lake for an angler to appear.
“It’s pretty slow right now,” Young said. “But it was pretty busy this summer.”
Even on tiny, picturesque Dalton, the value of stocked rainbows was clear, Young said.
“The biggest surprise to me was how many fish are actually being harvested out of these little lakes,” he said. “Dalton is pretty isolated. But there were a lot of campers fishing and harvesting trout, and locals — especially from Sturgis — were up here regularly.”
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Dalton also offers some pretty good fishing for smaller wild brook trout, which make a nice angling mix with the larger hatchery reared rainbows.
There was more catch-and release fishing this summer at Horse Thief Lake, which Young said got more “tourist” fishing pressure. Next year the study will move to Bismarck and Iron Creek lakes. Davis said the idea was to start with small lakes which are more easily studied to get a better idea of what’s going on with stocked rainbows.
But the problem was defined by data from other lakes. A year-long survey at Pactola Reservoir led Davis and other fisheries specialists to estimate that only about one in 10 rainbows stocked there were being caught by anglers.
A big part of that problem was northern pike, especially pike that were 2-feet long or more and were feasting on the 11-inch rainbows being stocked. GF&P is stocking larger rainbows in Pactola to give them a better chance at living at least until anglers can catch them.
But pike aren’t the problem everywhere in Black Hills lakes. And overall survey work indicates that return rates from one summer fishing season to the next, even in the best instances, typically fall well short of 50 percent.
Netting work by fish crews also indicates that those “missing” fish are not just cruising around the lake avoiding hooks. Them seem to disappear.
“We looked at carryover,” Davis said. “Of the fish stocked in 2017, how many carry over the ice period to open-water fishing in 2018? And we’re not seeing the carry over we’d hope for.”
Natural predators, including bigger fish, are certainly among the mortality factors. So is handling mortality among trout that are caught and released. But what else is going on?
Kelsen Young hopes to find out, in a masters-degree project that could put more “take” in put-and-take rainbow trout management for anglers in the Black Hills.