Wyoming Game and Fish Department sauger reintroduction to move into monitoring phase

Lydia Ellefsen
Posted 7/26/22

Sauger fish reintroduced

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Wyoming Game and Fish Department sauger reintroduction to move into monitoring phase


GLENDO – The Wyoming Game and Fish Department (WGFD) started reintroducing sauger to the North Platte River, above the Glendo Reservoir, in 2017, with the main goals of the project being to reintroduce a native species and provide a sport fish. Sauger is expected to reside in the river more frequently than walleye, providing fishing opportunities on the North Platte between Glenrock and Glendo.

“Sauger were historically, a native species in the North Platte drainage,” said Matt Hahn, a regional fisheries supervisor for WGFD in Casper.

Sauger are important to the North Platte River ecosystem as a native fish and a top-line predator. Hahn mentioned that they eat minnows, similarly to walleye, and sauger also serve as a host for native species of mussels.

Hahn mentioned they were once quite a common species but started to dwindle when the Pathfinder Dam was constructed, in the early 1900s. Hahn mentioned that sauger have been absent from the river for over 70 years.

Two main factors contributed to the dwindling and disappearance of the population: water flow and pollution. The water was shut off in the wintertime in order to store water, and the sauger population in the river dwindled after around the mid-1940s.

“The North Platte River used to be really, really polluted from how the cities treated their sewage, and oil refineries would dump any manner of things into the river, so it was a combination of very low flow in the wintertime combined with really toxic conditions often,” explained Hahn. “That was basically kind of what sealed the deal, but we don’t have those problems now.”  

These issues were addressed starting around the 1950s. From the 50s to the 80s, the river was cleaned up, and perennial flow was reestablished. Hahn mentioned that the river’s flow has been sufficient.

“The river’s no longer shut off, coming out of Pathfinder Reservoir and hasn’t been since probably the late 50s or so, everything’s good water-wise.

“Since they (sauger) disappeared, of course, there is flow year-round in the river now, and so we thought it would be a good idea to put the native species back, which is what we’ve done,” said Hahn.

“They’re (sauger) just really closely related to walleye, so people like fishing for them. They’re great eating, they’re fun to fish for, they can get fairly large,” remarked Hahn on the popularity of sauger as a sport fish.

Walleye can be found in the Douglas area in the spring before they move back down to Glendo. Introducing sauger would hopefully provide a fish that would be present in the river all year, or most of it, which would provide opportunities for sport fishing between the Dave Johnston Power Plant and Glendo Reservoir.

The sauger reintroduction has included stocking sauger in the North Platte River and a radio telemetry study. The stocking phase of the project is ending, and they are moving onto a monitoring phase that will last around another 3 to 4 years.

Stock mainly came from Nebraska, where sauger are also a native fish.

“Trades among states is really common,” said Hahn. “Wyoming trades trout to many other states in return for fish that we don’t raise ourselves. We trade with Arkansas for catfish, and we trade with Oklahoma for blue gill and in this case, we traded with Nebraska for sauger.”

“It’s just very economically efficient to trade with other states. It helps the other states out, and it helps us out at the same time,” Hahn said.

The department started stocking in 2017, and this year is the last year the department is stocking. Hahn mentioned the department is now shifting to a monitoring phase.

“We’re trying to figure out what parts of the river the fish are using, when they’re spawning, where they’re spawning, things like that,” said Hahn.

The radio telemetry aspect of the reintroduction included project has also included radio telemetry, where some adult fish had radio tags implanted in them. The tags allow for the tracking of the fish’s movement. Hahn mentioned that this allows the department to figure out where the fish are moving and doing. Less than 1% of the sauger population is tagged.

“We’ve got them on the ground now, and now we’re sort of in the learning phase I guess you’d say, in terms of trying to figure out their habitat needs and things like that in the river itself,” said Hahn.

Around $30,000 was spent on the radio telemetry study, though the study provided the benefit of also gaining information on many species in the river. Hahn mentioned that sauger have not just been tagged, that other species have as well, such as catfish and native suckers. Obtaining the sauger fish themselves were not particularly expensive.

“The biggest cost is probably sending someone to go get them [the stocks] and bring them back, so very, very little,” remarked Hahn on the cost of the reintroduction project.

Money from the project has come from research money through Game and Fish, which is able to be utilized for research state-wide. The research money is applied for through an internal program, so the project is in addition to Game and Fish’s normal operations.

Some challenges the reintroduction project has faced is supply from out-of-state trades to obtain stock, though Hahn mentioned it was not a huge challenge, just a minor speedbump. 100,000 fingerling sized sauger were requested every year, based on expected number of natural mortality and angler harvest. With 100,000 fingerling sized sauger, several hundred adult sauger fish were expected to spawn.

“I think we only hit that number (100,000 fingerling sized sauger) once, and then because of some of the challenges from the out-of-state hatcheries, we ended up, that last two years, stocking fry, which are very, very small fingerling saugers around 2 inches so long, and a fry is a quarter of an inch long or so.”

Some success the reintroduction has accomplished was the survival of the fish.

“We’re starting to see quite a few fish in the spring when we’ve done electro-fishing surveys. We’re seeing a lot of them in the river,” said Hahn.

“It’s just providing a sport fishing opportunity that’s fairly unique to this part of Wyoming,” said Hahn on the value of the reintroduction project to the community. “The closest place to here in Wyoming to go fish for native sauger is clear over in the Bighorn River Basin.”

Fishing for sauger has always been open, even during the reintroduction project. As soon as they were stocked in the river, if people wanted to fish for them, that was legally allowed. Right now, there are restrictions on fishing sauger, with there being a two sauger limit. They can be of any size, but people are only allowed two. Because there are tight restrictions on the number of sauger individuals are allowed, it has not hampered the reintroduction project.

“We don’t think we’re seeing too much harvest on the sauger population,” said Hahn. “There’s not a ton of sauger in there yet either. What we’re able to provide through stocking is a fraction of what we should be able to get through natural reproduction once those things really start spawning on their own.”

The radio tags are about the size of an AA battery and are found inside the fish’s body cavity, so the tagged fish are noticeable. If a tagged fish is caught, people can release them back into the river. If the angler chooses to keep the fish, Hahn mentioned that it would be appreciated if people were to return the radio tags to the department, as the tags are several hundred dollars each. Returned tags will be recycled by putting it into a new fish.

“People can call the phone number printed on the tag (307-473-3400) to report the harvest of a tagged fish and we will make arrangements to get the tag back,” stated Hahn.

Although the reintroduction could impact tourism to the area and the park, Hahn mentioned that he thought the walleye fishery is currently a huge draw for people and the reintroduction really just complements that fishery.

“There could be a few people that come just to fish for sauger, but by and large, I think, you know, the draw is already there to bring people because of the real-world class walleye fishery, and this just kind of compliments it,” said Hahn.

This story is supported by a grant through Wyoming’s Established Program to Stimulate Competitive Research (EPSCoR) and the National Science Foundation.