By Mark H. Stowers
Fishing in Michigan is big business. And that’s no fish tale. In both commercial and recreational industries, billions of dollars are generated in economic activity, with nearly two million Michigan residents and 334,000 non-resident tourists fishing in Michigan each year. Approximately one-third of all recreational fishing in Michigan depends on stocked fish, including a substantial portion of Great Lakes trout and salmon fishing. For the fiscal year 2003-04, fish production in Michigan cost $7,242,118, which accounted for 30 percent of the Department of Natural Resources (DNR) Fisheries Division’s budget. Anglers spend approximately $850 million per year with effects on the tourism and fishing equipment sectors of Michigan’s economy of $2 billion per year.
The Great Lakes Fishery Commission estimates that recreational fishing in the Great Lakes provides more than $4 billion into the state of Michigan’s economy. Commercial fishermen are generating over $4 million annually harvesting anywhere from 1.9 to 2.5 million pounds of fish. And one reason the industry continues to be healthy and moving forward is the work of the fish stocking process.
Through August of 2024, the DNR had stocked more than nine million fish – 321 tons – including 12 different species and one hybrid across an array of Michigan bodies of cold water, cool water and warm water. The fish stocked include l;ake trout, brown trout, rainbow trout, brook trout, Northern pike, muskie, steelhead salmon, chinook salmon, Atlantic salmon, Coho salmon, walleye, grayling and splake (hybrid of brook trout and a lake trout.)
According to a published 2004 DNR study, there are four purposes for stocking fish including restoration of fish populations, providing diverse sport fishing opportunities through introductory, continuous and supplemental stocking, improving ecosystem balance and aiding experimental studies. Numerous factors come into play before stocking decisions are made. Costs, benefits, effects on the aquatic community, genetic effects on existing fish populations, biological soundness, community support, geographical need, existing regulations and availability of fish are the major factors considered. Protecting and restoring habitat is usually the most important method for managing self-sustaining fish communities. And stocking is usually not recommended where fish populations are self-sustaining, such as bass and bluegill and several others.
Stocked fish can negatively affect healthy fish communities through degradation of genetic fitness, competition, predation and other biological factors. Stocked fish generally demonstrate poor survival in the presence of healthy fish populations, so benefits are usually small and sometimes lacking. To assess the success of management actions in areas of natural reproduction, hatchery stocks are uniquely marked to distinguish hatchery and wild fish and to assess possible hatchery-wild interactions.
Stocking Michigan lakes streams, and rivers with varying fish species provides many benefits for fishermen and outdoorsmen, as well as keeping those waterways in balance and healthy. However, there can be drawbacks. Too much of a good thing can unbalance a body of water and create unintended problems. The process of stocking has been around since the 1880s in Michigan, and the work continues today with continual research and development to keep fisheries across the state in balance.
The idea of fish stocking was the idea of Robert Roosevelt, a state of New York congressman who was an early conservationist (and uncle of President Theodore Roosevelt.) He captained the idea to establish the U.S. Fish Commission in 1871 to investigate declining fisheries and the potential of aquaculture to replenish depleted waterways. That urging led to the new transcontinental railroad shipping brook trout from east to west and rainbow trout from west to east, often stopping repeatedly en route to seed local bodies of water. This early stocking was haphazard and just thought to be a good thing but led to some native fish becoming non-existent. In 1910, the yellowfin cutthroat trout that hit weights of 11-plus pounds disappeared from Colorado’s Twin Lakes. The hybridization with rainbow trout and the competition of other introduced game fish even killed off the silver trout in New Hampshire. A 1989 study showed that the introduction of nonnative fish directly caused the extinction of more than two dozen North American fish species. The problem has become an international one as well, according to San Francisco State University Herpetologist Vance T. Vredenburg.
“The California golden trout is a really beautiful fish and because of that you can find them introduced in Mexico and the Andes. You can find them in New Zealand. You can find them on Mount Kilimanjaro.”
The introduction of non-native fish can disturb the ecosystem in different ways. They can take over or interrupt the food sources of other species, including frogs and birds and start to limit their population. Without the proper study of a body of water, fish stocking can cause problems. In Michigan, the cisco has become a threatened species and grayling were nearly extinct but the DNR has been working to maintain native fish and broadened its efforts to help restore them as well. Fish stocking by the state of Michigan began in 1874 when Atlantic salmon fingerlings were released from the Crystal Springs State Fish hatchery located near Niles. From then on, the state has continued its efforts and refined the process along the way.
Cleyo Harris works for the DNR Fisheries Division as a fisheries technician in the Lake Erie Management Unit (LEMU) and has more than 22 years of experience as a fisheries biologist.
The 2003 Michigan State University graduate’s territory encompasses all of the waters that drain into Lake Erie, including all or portions of Hillsdale, Lenawee, Livingston, Macomb, Monroe, Oakland, St. Clair, Sanilac, Washtenaw and Wayne counties. LEMU covers a diverse array of inland waters and nearshore Lake Erie from a field office located in Waterford. Harris came about the job naturally.
“I grew up fishing. My parents owned a bait shop, so I got to know one of the local biologists over in Jackson (where a previous DNR office was located) and after talking to him, I got into the field and realized that's what I want to do.”
He delved into the nuts and bolts of the fish stocking process.
“For the most part, a lot of our lakes, especially in southern Michigan and southeast Michigan, are mostly naturally reproducing lakes. We don't have to restock much of anything. The stocking that we do is when we want to provide opportunities or we're trying to pull increased predation in a lake to get bluegills or other species to grow better. More often than not in our area of the state, it's to provide (fishing) opportunities for people.”
But not just any fish can be stocked in any lake or body of water. Harris used trout as an example.
“The species has to be able to survive in there. And not every lake is suitable for trout. Not every stream is suitable for trout. We have a lot of really warm water lakes and the trout need that cold water habitat. We have to take that into consideration,” he said.
Research is done to find the best areas for each species of fish to stock. Water temperature and the oxygen mix are key factors.
“We have very few lakes that have enough cold-water habitat in the summertime. We have a lot of lakes that get really deep. But once you get below that thermal climb or where the lake stops mixing from all the wind. That area is well-oxygenated at the surface, probably the top 15 feet in the summer. Once you get below that, the dissolved oxygen really drops out and so fish cannot survive below that.”
Harris noted that “a few lakes, like Maceday Lake, Cass Lake and some other lakes do have those cold-water reserves that go really deep into the lake. Maceday Lake is one of those lakes where we do stock trout to provide that opportunity.”
When stocking fish, attention must be paid to the lake's population so that no particular species is overrun.
“We have naturally reproducing species like cisco that are cold water in those lakes as well and that's a state-listed species,” he said. “We can't stock competitors and predators. We don't want to stock very many competitors and predators on top of a state-listed species since we're trying to protect them.”
Plenty of research is done beforehand to understand the needs of any particular lake, river or stream.
“We do surveys. When we're making a determination for lakes, most of them are naturally reproducing. All of our lakes around here (Oakland County) have typically bluegill, pumpkin seed, crappie, and largemouth bass. Some of our lakes have smallmouth bass but not all of them. Most of them have largemouth bass. They have a lot of northern pike as well. All of those species are typically naturally reproducing,” Harris said.
The survey consists of setting a variety of different gear in the lake and then collect the fish, take samples, measurements, and get all the different fish species in the survey.
“We then look at the growth rates and other data and make a determination based off all that data that we collect to see if it does or doesn't need help. If a Northern Pike lake, for example, can support Northern Pike but they're just not reproducing very well because a lot of the wetlands are disconnected and they don't have a lot of spawning habitat anymore, we come back in and stock if we have the fish available. A lot of our stocking in Oakland County is walleye and we don't have a lot of naturally reproducing walleye in the county even though we have a world-class walleye fishery very close in the Lake Erie and Lake St. Claire River system that’s naturally reproducing inland. We don't have that type of resource, so we have to stock them and if we don't stock them, the walleye populations will just completely go away.”
Using a variety of survey techniques to evaluate the stocking process to gauge fish growth, future stocking can be adjusted. Sometimes stocking is to produce a better fishing opportunity and sometimes stocking a certain species is to predate another, such as stocking walleye to target a larger than needed bluegill population.
“A lot of people like to target bluegill, and so we're trying to improve opportunities for bigger bluegill in Crescent Lake,” Harris said. “The walleye will eat bluegill when they're really small, and so they're reducing that competition and they can get a better jump start in those early life stages to grow faster and get to a better size class.”
The surveys continue, Harris said, so “it doesn't tip the scale in the other direction. We know there's some lakes we surveyed them enough over the years. We have an idea of how much survival we get out of these and with our current stocking rates, we don't have to tweak a whole lot at this point. We get somewhere between 0.5 and 1.5 walleyes per acre, and that's not a big walleye fishery.”
Up north lakes stocked with walleye have a lower survival rate and it takes time for them to grow to a size where they begin eating bluegills – up to three years. That’s why fish size limits are created for fishermen to adhere to.
“We put walleye in at about one and a half to two and a half inches so we know some of those are going to get eaten before they get to a large enough size to eat bluegills,” Harris said. “It takes about three years to reach legal size – 15 inches for walleye,”
One way the DNR surveys is to tag and track fish.
“Marking and tagging fish helps DNR researchers understand fish survival, age, growth and movement, as well as the amount of natural reproduction of a species,” said Jay Wesley, the DNR’s Lake Michigan basin coordinator.
Through mass marking assistance by the U.S. Fish and Wildlife Service, Great Lakes states mark popular game fish like steelhead, Chinook salmon, Atlantic salmon, brown trout and lake trout. These marks include both clipped adipose fins and coded-wire tags.
The DNR has used a coded-wire tag program to mass-mark various fish species in Michigan since the 1980s. The program involves implanting a small, coded-wire tag, invisible to the naked eye, into the snout of a fish. The tag is small – like the tip of a lead pencil – and lab technicians are needed to remove it.
Trout and salmon containing a coded-wire tag can be identified because their adipose fins (the small, fleshy fin between the dorsal and tail fins) have been removed. The DNR asks that anglers who catch a fish with a clipped adipose fin remove and freeze the head of the fish and turn it in at a local drop-off station in Michigan.
Jaw tags – metal bands attached to a fish’s upper or lower jaw – are also used. Fish tags or markings include temperature depth-recording tags discovered when cleaning a fish; jaw tags, which are metal bands attached to a fish’s upper or lower jaw; anchor tags inserted near the base of a fin; and fin clips (total or partial removal of fins) on fins other than the adipose fin.
Anglers can report marked fish through the DNR’s Eyes in the Field app to provide information such as species, tag details, photos, and date and location caught, or by contacting a local DNR fisheries office. Some tags can be reused, and some tags offer small monetary rewards for reporting them.
According to Harris, the cycle of stocking lakes, streams and rivers across Michigan varies. Cass Lake is stocked every other year “As long as we have fish available and then Crescent Lake and Big Lake, we're stocking every third year.”
Harris explained the different hatcheries carry a variety of fish and has different processes depending on the type of fish.
“We have six hatcheries that are currently operating. Like Marquette, being all the way up in the UP, they raise all of our lake trout. Whereas Wolf Lake, they do our muskie production, steelhead and chinook. And they do some walleye, too,” he said.
The hatcheries either have stock fish that lay eggs that are hatched and fed and grown to stocking size. Some hatcheries have eggs brought in that have been collected.
“It depends on the species. For chinook and steelhead, we have weirs on specific rivers that stop the migration of fish up the river and force them into our ponds and we'll collect them. And then for species like lake trout and brown trout, we have what we call captive broodstock where we have adults in the hatchery that we collect eggs from.”
Walleye gametes (eggs and sperm) are collected from rivers and brought to the hatchery.
“They go to the hatchery for a few days or a bit longer until the eggs actually hatch. Three to five days after they hatch, we put them in rearing ponds at Drayton Plains in Waterford or Camp Dearborn in Milford. And then 45 to 55 days later, we're pulling them back out of the pond to stock in local lakes.”
Other fish take more time. Steelhead salmon are moved to a cement raceway stream where electric feeders are set up.
“They can keep putting food to them because those fish are in the hatchery for a year,” Harris said. “Muskies can be spring to fall and released. Some are held longer and used as a broodstock source in lakes like Lake Hudson and Thorn Apple Lake. We also use the Detroit River.”
Most fish spawn only once a year but some Michigan species will spawn multiple times a year, according to Harris. One key part of the process is keeping fish disease-free so the hatcheries are on constant alert for any diseased fish.
“We do a lot of testing in our hatcheries from the adults that we're sampling in the wild to get gametes from. We send those to the lab. We take samples of the eggs,” he said. “We take samples throughout the whole process until the fish go out to make sure we're not stocking anything that has any diseases or pathogens. And if we do have issues, then we're going to have to go out and get them. If we find any disease, we have to kill the whole lot. That doesn't happen very often.”
Regarding private hatcheries, Harris explained the DNR still has oversite.
“We require them to get a permit before they can sack any fish. They have to show that those fish have been tested for any pathogens and meet our requirements. We have to get their certificate number and verify that they've been tested,” Harris said.
In addition to the 12 species of fish that are grown in hatcheries, there is one hybrid fish and one native fish that is being reintroduced.
“The newest thing that we've been working on in our hatcheries is the grayling, which is an extinct species in Michigan. So historically, we're here in Michigan and introduced them back into Michigan. And we've tried this a few times and we're trying it again. We have a brood stock source in our hatchery at this point. And splake is a hybrid that we stock. It’s a hybrid between a brook trout and a lake trout. That one's mostly stocked up north in the UP. We do have a few lakes in southern Michigan and in the lower peninsula that we stock. Maceday Lake being one of them as a local one,” according to Harris.
The grayling stocking has been progressing positively.
“A long time ago, that was one of the main food fish that loggers were going after because it was right there and they were easy to catch. But after multiple seasons, they got wiped out. They're beautiful, too. They have a large dorsal fin that's really colorful. They're a cold-water species. And we're currently on the global landscape at the lower edge of their range.”
The next phase of bringing Arctic grayling to Michigan waters will be a ceremony Monday, May 12, at the Oden State Fish Hatchery Visitor Center in Alanson, Michigan. The DNR will provide approximately 400,000 grayling eggs to the Little River Band of Ottawa Indians, the Little Traverse Bay Bands of Odawa Indians and the Grand Traverse Band of Ottawa and Chippewa Indians. These partners will reintroduce the eggs at locations along the North Branch of the Manistee River, the Maple River and the Boardman-Ottaway River.
The Arctic grayling (Thymallus arcticus) – often referred to simply as “grayling” – are a freshwater fish in the salmonidae (salmon) family. They have a unique and striking appearance, with a prominent, sail-like dorsal fin and often iridescent markings. Grayling can be found in the Arctic Ocean and Alaska, as well as in rivers and streams of the northern U.S. and Canada.
Native to only Michigan and Montana in the lower 48 states, grayling historically were found in cold-water streams in Michigan’s Lower Peninsula and were common in the Manistee and Au Sable rivers – the city of Grayling, Michigan, along the Au Sable, is named after the Arctic grayling. Despite the importance of grayling as a food source, sport fish and cultural resource, habitat destruction, unregulated timber harvest and pressures from non-native fish species led to the extirpation (local extinction) of grayling from Michigan by 1936.
In 2016, the DNR, in partnership with the Little River Band of Ottawa Indians, announced a proposed initiative to reintroduce Arctic grayling to the state, creating the Michigan Arctic Grayling Initiative, or MAGI. Consisting of more than 50 partners, the MAGI seeks to establish self-sustaining populations of this historically and culturally significant species within its historical Michigan range.
As previous attempts to bring back the grayling have failed, new technologies and methods have improved the likelihood of effective reintroduction. The grayling eggs being reintroduced will be placed in streamside incubators that will allow them to imprint on the waters in which they are placed, helping them thrive. MAGI partners will closely monitor the hatching and development of the fry, as well as follow up on how they move through these systems as they grow.
The return of grayling to Michigan is a years long process, and this initial handoff of eggs begins the reintroduction phase of this effort. In November 2023, three Michigan lakes were stocked with Arctic grayling that were surplus from the DNR’s grayling broodstock. While establishing the broodstock was an important milestone in the reintroduction process, this stocking did not (and was not intended to) establish a self-sustaining wild Arctic grayling population.
“One of the biggest things is making sure we have the right habitat. Outside of lakes, the other stocking we do is in our rivers. Like the Clinton River, where we have like a captive brood stock in some of our hatcheries. And occasionally they have to replenish those stocks. And when they need to remove some of those brood stocks from the hatcheries, we then bring those down to some highly populated areas,” Harris said. “Southeast Michigan being one of the most populated areas. We stock the Huron River over at Proud Lake. And the Clinton River and Auburn Hills area with these adult brood stock. They’re big fish. They're 17-to-24-inch trout and they're instant fisheries for people to target. We try to make sure we let all the communities know where we're going. Stocker Fest at Proud Lake is an annual thing. We regularly bring walleye only for the first month and kids could harvest one fish in that first month and then it opens up because it gets hit hard. The Clinton River is open as soon as the fish go in. We have people in their waders with their fly rods.”
With bluegill and bass having a high population, the DNR does not typically stock those species.
“They're really good at reproducing on their own; they don't need us to stock. We just protect the populations that are there so that they can reproduce on their own. We've tried to stock trout all over the place in many streams and found out they didn't work everywhere. We learned over that process of what habitat metrics we need to collect and what we need to look at to make sure that that these species are going to be able to survive and we're going to use our public trust and the public funding that we have because my wages come out of fishing game licenses. That’s what pays for us to do our work and we get some federal sport fish restoration money and we sell stock fish as well. This is all paid for by our anglers and hunters,” Harris said.
The DNR does partner with other organizations such as Trout Unlimited.
“We work with our partners as much as we can. That's how we get habitat projects done. Locally, we have the Clinton River Watershed Council, the Huron River Watershed Council andFriends of the Detroit River,” Harris said.
Dan Paske is president of the 275-member, Rochester-based Guardian chapter of Trout Unlimited, a national organization that was founded in Michigan in 1959 and is now headquartered in Virginia. The non-profit is dedicated to the conservation of freshwater streams, rivers and associated upland habitats for trout, salmon and other aquatic species. Paske’s chapter has a special interest in the Paint Creek stocking of various trout.
“The organization continues to work so trout can thrive and be enjoyed by future generations. Trout is a unique species of fish. It can only survive in cold water, which generally is defined as, you know, water temps that are below, you know, 65 degrees,” Paske said. “We've really focused most of our conservation work on is Paint Creek in Oakland County. And Paint Creek is really the only cold-water creek in southeast Michigan.”
Each Trout Unlimited chapter focuses on “habitat conservation and restoration. On Paint Creek there's a stocking that the Michigan DNR does of brown trout, but we've also noticed that there's natural reproduction going on there as well, not only of brown trout, but of rainbow trout. The theory is if you can create the habitat, it makes the water conditions more ideal for trout to sustain themselves in that environment.”
The chapter has a four-phase project on Paint Creek creating trout habitats dating back to 2000. Recent fish stocking in Oakland County has focused on walleye to help with bluegill population and stocking trout to provide fishing opportunities down here.
Aaron Switzer and Jeremiah Blaauw are part of the stocking process. Switzer has been with the DNR fisheries division for 25 years with most of that in fish production. He worked his way up from his one day just walking into the Wolf Lake Fish Hatchery and asking for a job. From his temp job, he now manages the program. Blaauw said he “wears three hats. I deal with all the health within our six state fish hatcheries, as well as the public/private aquaculture business in Michigan. I also deal with all stocking in inland and Great Lake fish that are marked or tagged.”
The duo explained a bit more of the process noting the DNR uses 17 specialized trucks, that have traveled over 100,000 miles taking 451 trips to 691 restocking sites.
“Generally speaking, fish production, our budget annually is around $10 million, and that rearing in transportation, it takes up the lion's share of that,” Switzer said. “About $4 million is what I estimate that we put towards rearing in transportation.”
The stocking season was a success this past year, according to Switzer.
"We had another excellent spring and summer stocking season that will bring ecological benefits and fishing opportunities to Michigan anglers," Switzer said. "Thanks to the hard work and dedication of our staff, healthy, high-quality fish were reared and delivered to stocking sites in excellent condition. The numbers produced and stocked met the targets for most areas."
The number and type of fish produced vary by hatchery, as the source and temperature of the water determine which fish can be raised in that location. Fish are reared in Michigan's state fish hatcheries anywhere from one month to 1 1/2 years before they are stocked.
Switzer said, “The Chinook salmon process is usually occurring at about six months so the first spring after they’re spawned in the fall, they're ready to go out to big water. Other species like Coho and Atlantics you're looking at 18 months in the fish hatchery before they're ready. Small steelhead take about a year from springtime spawn to the next spring. Browns and rainbows in the cool water again can range from nine to fifteen months in the hatchery. Walleye fry plants which are five-day old fry that have hatched and we'll stock high numbers or we'll keep them in our cool water facilities rearing ponds and get growth on them to a spring fingerling and stock them at that point when they're two to three inches long. We even do some fall fingerlings where we keep them all summer and continue to give them forage (food) but forage costs money which makes those fish more expensive but they do have a higher survival rate.”
And the stocking and growing calendar is planned at least two years out, according to Switzer.
“Each fishery has their own calendar with lakes that are going to be restocked. I'll be working on the 2027 rearing assignments. We're already looking forward to our responsibilities at each hatchery and those will be finalized in the summertime because it does take a lot of planning up front and enough eggs to of course make those fish.”
In Michigan, there are six state and two cooperative hatcheries working together to produce the species, strain and size of fish needed for fisheries managers. These fish are delivered and stocked at a specific time and location to ensure success. An update of each hatchery showed that the Marquette State Fish Hatchery (near Marquette) stocked 323,710 yearling lake trout, brook trout and splake (a hybrid of lake trout and brook trout) weighing 41,771 pounds. They also stocked 90 inland and Great Lakes sites.
The Thompson State Fish Hatchery (near Manistique) stocked 1,171,696 fish including yearling steelhead and spring fingerling Chinook salmon. These fish weighed 102,442 pounds total. This hatchery stocked 64 sites (the majority located on the Great Lakes).
The Oden State Fish Hatchery (near Petoskey) stocked 762,074 yearling brown trout and rainbow trout that in total weighed 112,704 pounds. Oden also stocked 3,689 adult brown and rainbow trout that in total weighed 8,148 pounds. This hatchery stocked 159 inland and Great Lakes sites.
The Harrietta State Fish Hatchery (in Harrietta) stocked 684,487 yearling brown trout and rainbow trout that in total weighed 84,812 pounds. This hatchery stocked 200 sites that were mostly located inland.
The Platte River State Fish Hatchery (near Honor) stocked 2,272,494 fish weighing 161,396 pounds, including yearling Atlantic salmon, yearling coho salmon and spring fingerling Chinook salmon. Platte River also stocked 31,514 Skamania steelhead obtained from the Indiana DNR that in total weighed 4,314 pounds. This hatchery stocked 23 sites with the majority located on the Great Lakes.
The Wolf Lake State Fish Hatchery (near Kalamazoo) stocked 1,485,711 fish, including yearling steelhead, yearling muskellunge and spring fingerling Chinook salmon that in total weighed 123,381 pounds. Wolf Lake also stocked 22,067 channel catfish obtained from the Ohio DNR, with a total weighing 670 pounds. This hatchery stocked 51 sites with the majority located on the Great Lakes.
In addition, a cooperative teaching hatchery at Lake Superior State University (in Sault Ste. Marie) stocked 19,285 Atlantic salmon, weighing 1,849 pounds, into the St. Mary’s River.
Included in this year’s total fish stocked were 2.4 million walleye spring fingerlings reared in ponds by the DNR, with extensive support provided by local sporting organizations. These fish were stocked at 61 inland lakes and rivers and Lake Michigan.
Some hatcheries will also provide fish for a few additional stockings (consisting of brook trout, Atlantic salmon, walleye, lake sturgeon and muskellunge) to be made this fall. The lake sturgeon will come from the cooperative hatchery in Tower, Michigan, that is operated with Michigan State University.
H
arris notes that “for what we stock in Oakland County alone, we spend an average of about $112,858/year stocking walleye, brown trout, and splake in Oakland County with the occasional lake trout being stocked.”
DNR numbers show that since 2020, 16 different Oakland County water bodies – both lake and river systems – have gotten five different species, including brown trout, lake trout, rainbow trout, splake, and walleye. They include Big Lake, Big Seven Lake, Cass Lake, Clinton River, Crescent Lake, Huron River, Kearsley Creek, Lake Orion, Lakeville Lake, Long Lake, Maceday Lake, Paint Creek, Pontiac Lake, Union Lake and White Lake.
The decision to stock a public lake is made by the DNR. But with so many lakes in Michigan, it’s an ongoing process.
“We have fisheries biologists in each management unit and then a crew of technicians. Some lakes are on a rotational basis, some are on a discretionary basis. But they go out and sample those lakes, look at predator-prey ratios and other data and then the biologist writes a prescription,” Switzer said. “That prescription is what we use to allocate fish to a lake. But a biologist may only be able to conduct 8 to 12 surveys a year. And with 11,000 public water bodies in the state of Michigan, you start doing some math on that, it will take us a career plus, maybe even a lifetime to get to everything surveyed.”
Blaaww added, “These lakes have to have public access. That's a big thing on the completion of those surveys to make sure that our fish are gaining… Another big thing is restoring threatened species. It's not only game fish that we do but it's also sturgeon. We have a cooperative hatchery at Black Lake and they release sturgeon there. We have another one that's run by DNR personnel up in the UP, Cedar River in Ontonagon. They're doing sturgeon releases too. They actually collect fry in the springtime, bring them back to the streamside rearing facilities, raise them up to fall fingerlings. They're anywhere between 10 and 12 inches. And then release them back into the river in hopes to increase that population and enough adults where they can capitalize on the habitat and reproduce on their own.”
Professional walleye fisherman and PhD candidate at Wayne State University in Aquatic EcologyAli Shakoor explained a possible downside of fish stocking. “I know in Lake Orion, Lake Oakland, they're doing some walleye fishing and putting in a bunch of fingering. There could be negative ecological impacts. Walleye are piscivorous, so they're a predator. They feed on other fish. They exert this top-down control on the ecosystem through predation. Baitfish populations or juvenile fish populations of other species, bluegill, crappie, blunt-nosed minnow, fathead minnow, whatever those smaller fish. If their populations aren't healthy, there could be negative impacts to those populations. When these fish are stocked in a lake, the DNR doesn’t just say, ‘hey, the walleye population is low here. Let's go throw in 500 fingerling walleye’. They have to go out and do an assessment. They're going to assess populations of other fish because it's going to be competition. They're going to assess populations of prey fish because that's another form of pressure that's going to be exerted on those prey fish populations. Bass and walleye are going to compete for some of the same fish. Bass and northern pike. Bass and bluegill or perch at certain life stages may compete for certain types of food sources.”
He also explained, “It's important that they take a holistic view of the lake’s spawning habitat. If they put in too many walleye, then density dependence would dictate that you're going to be competition. If the ecosystem can't support those 500 or 1,000 fingerling walleyes you may have decreased growth rates or those fish may become stunted. They're not going to grow properly. They may stop growing at 12 inches and never reach legal size. They may reach their full potential. There's a lot of background work that needs to be done before the decision is made to stock a particular species of fish in a body of water.”
Fortunately, that’s just what the DNR and their supporting organizations are doing to help keep the Michigan fish supply healthy and strong for generations of fishermen and outdoorsmen to come.