By Craig Springer — for the USFWS, Office of Conservation Investment
Muskellunge: the fish of 10,000 casts. Throwing a sawed-off broomstick-sized plug with multiple treble hooks for hours on end can wear out your arm. That’s not a lot of fish in the boat for the hours spent on a big lake, moving from cove to cove, ledge to ledge, steering with the click and burr of a trolling motor. Add in the fetch of wind over broad waters and suffering the waves that all add to the difficulty.
Muskie are notoriously difficult to catch. But still, any ardent muskie angler would call it all good; few anglers are more enthused about their quarry than one who fishes for muskie.
Iowa Department of Natural Resources fish biologist Jonathan Meerbeek recently released the findings of a multiyear research project that should enthuse muskie anglers in Iowa and beyond. His work stands to make muskie conservation more efficient and the fishing better anywhere state fish and wildlife agencies rely on supplemental stocking from hatcheries. His research and the operations at the state fish hatcheries are funded by Sport Fish Restoration dollars, via federal excise taxes paid by tackle manufacturers as well as a portion of motorboat fuel taxes.
A great many muskie fisheries in the United States are maintained and managed by periodic stocking supported by Sport Fish Restoration dollars. And so it is in one Iowa fishery, Spirit Lake, on the Iowa-Minnesota state line. How the fish fare shortly after release is a critical period, one better understood thanks to Meerbeek’s work.
Meerbeek and his colleagues at Spirit Lake and Rathbun State Fish Hatcheries implanted 108 young muskie with radio transmitters over multiple time periods and followed their habits and predilections, post-stocking. One group of muskie were immediately stocked after a six-hour journey, another group rested 36 hours in the hatchery truck tanks following the journey, then released. The telemetry returns showed no great difference in survival or dispersal among those two groups.
But there was one great difference: the size of fish at release proved to affect survival. The bigger fish leaving the hatchery had a better chance of survival in the wild. Armed with that information, a subsequent group of young muskie were held in the hatchery up to another 40 days to increase their size; 30 muskies in that group were radio-tagged and followed. That group’s survival improved an astonishing 73.4 percent.
Meerbeek performed another comparison of stocked muskie, implanted with radios. Some were released in May, 17 in all, and another grown out larger, 21 total, stocked in June and followed with a radio receiver.
Finding a radio signal emitted from a Great Blue Heron could only mean one thing. The bird swallowed a muskie. Bird predation proved significant in reducing muskie survival to larger sizes. Meerbeek noted that in a different but similar telemetry study, a pelican emitted a radio signal and regurgitated five 14-inch muskies before it could fly.
“Growing out bigger fish is better for survival of young muskellunge,” said Meerbeek. “Time of stocking matter, too. Later in the spring when water is turbid—less clear—it makes muskies harder to see for birds—pelicans and herons—and predatory fish like walleye, northern pike, largemouth bass, and other muskies.”
Bigger fish are more expensive to grow out and stock, but it could be more effective in managing muskie anywhere in the country where state fish and wildlife agencies rely on hatchery fish to manage muskellunge.
Growing bigger muskie before stocking, stocking later in the year, and out in deeper water is a take-home message from Meerbeek’s work.
“It’s about predator avoidance. Muskie that live beyond 25 days post-stocking seem to have a marked chance of survival to bigger sizes,” said Meerbeek.
A proxy measure of success is casting a big plug adorned with treble hooks raked by the toothy maw of a big muskellunge. The twisting and turning and tugging like a tarpon at the end of the line is worth those other 9,999 casts.