Learn more about declining Great Lakes prey fish populations

A cross-basin overview reviews status and trends of prey fish from 1978 to 2016.

The research vessel Sturgeon conducts prey fish trawl surveys on the Great Lakes. Photo: Great Lakes Fishery Commission

The research vessel Sturgeon conducts prey fish trawl surveys on the Great Lakes. Photo: Great Lakes Fishery Commission

There were massive changes in the Great Lakes fish communities during the 20th century. During that time proliferation of sea lamprey, alewife, and smelt occurred. In the mid-20th century the collapse of native fish communities, such as lake trout and ciscoes occurred. In the late 20th century there was stocking of trout and salmon; the invasion and proliferation of zebra mussels, quagga mussels, spiny waterfleas, and round gobies; declines in Diporeia (small, shrimp-like crustacean), alewife, and rainbow smelt; and the oligotrophication of Lakes Huron, Michigan, and Ontario because of low phosphorus inputs and the cropping of phytoplankton by quagga mussels. An oligotrophic lake has a deficiency of plant nutrients, usually accompanied by an abundance of dissolved oxygen.

Given this scenario questions are asked on how similar or different are the changes in fish communities across the Great Lakes and what could be causing these changes? Michigan Sea Grant and Michigan State University Extension recently held an educational session at the Michigan Fish Producers Association Annual Conference. At the conference Chuck Madenjian of the U.S. Geological Survey Great Lakes Science Center discussed this topic and reviewed data prepared by his colleague Owen Gorman with other contributors from U.S. Geological Survey, Ohio Department of Natural ResourcesNew York Department of Environmental ConservationPennsylvania Fish and Boat Commission, and Ontario Ministry of Natural Resources and Forestry. Here is a summary of his presentation on Great Lakes prey fish:

Assessments of Great Lakes prey fish stocks have been conducted annually by the U.S. Geological Survey since the 1970s using bottom trawl surveys. The focus of the surveys has been on the prey species cisco, bloater, rainbow smelt, alewife, and round goby. Total prey fish (alewife, rainbow smelt, bloater, and cisco) biomass declined during 1978-2016 in Lakes Superior, Michigan, and Huron. Lake Ontario is now different based on a new correction factor and prey fish biomass was not available for Lake Erie.

Coregonids

There was a synchronous decline in coregonid (whitefish, cisco or lake herring, bloater, kiyi) biomass in Lakes Superior, Michigan, and Huron during 1978-2016 with peak biomass occurring during 1989-1992. Lake Huron showed a coregonid rebound during 2008-2012. Predation does not appear to be the primary driver of bloater dynamics during 1978-2016. Some fishery biologists believe predation on bloaters by salmon and trout is more important nowadays than during the 1980s and 1990s, but most of the diet data do not support this contention. There may be population-intrinsic factors (sex ratio); changes in climate patterns; changes in trawl catchability over time due to changes in bloater behavior or increased water transparency in Lakes Michigan and Huron.

Alewife

In Lakes Huron and Michigan there was a synchronous decline in alewife biomass during 1978-2016. Alewife is the dominant prey fish in Lakes Huron, Michigan, and Ontario. It is rare in Lakes Superior and Erie. Predation has been the primary driver of alewife dynamics in Lake Michigan since the 1960s and it is likely the main driver of alewife dynamics in Lakes Huron and Ontario as well.

Rainbow smelt

Rainbow smelt had a synchronous decline in Lakes Superior, Huron, Michigan, and Ontario during 1978-2016. Lake Superior peaked earlier than the other lakes in 1978. In these four lakes, rainbow smelt was an important prey species before the mid-1990s and is now a minor prey species. Predation appears to be the primary driver of rainbow smelt dynamics in Lake Superior but not in Lake Michigan.

Round goby

Round goby biomass increased in Lakes Michigan, Huron, Erie, and Ontario during the 1990s or 2000s, then peaked, perhaps even decreased somewhat, and appears to have leveled off in all four lakes. Further increases in round goby biomass are not expected. Round gobies in Lake Superior are mainly limited to harbors. Round goby populations in Lakes Michigan, Huron, Erie, and Ontario now appear to be under some degree of predatory control as they are fed upon by smallmouth bass, lake whitefish, burbot, lake trout, brown trout, yellow perch, other fish and birds. There are relatively high annual mortality rates (> 60% each year) in open waters of Lakes Michigan, Huron, and Erie.

Great Lakes net-pen aquaculture—real and perceived risks to the environment

Michigan Sea Grant addresses environmental issues surrounding net-pen aquaculture in the Great Lakes at recent Annual No-Spills Conference.

Great Lakes net-pen aquaculture—real and perceived risks to the environment

In the last several years there has been a great deal of discussion about net-pen aquaculture in the Michigan waters of the Great Lakes. Much of the attention about Great Lakes net-pen aquaculture is the generation of large quantities of fish waste from these fish production operations as well as the consequences if these fish escape into the environment. The main issue with fish waste is the release of phosphorus which is the growth limiting nutrient for primary production in freshwater ecosystems. Although some phosphorus is necessary to drive the freshwater food chain, concern arises when excess amounts of phosphorus are available which can result in significant algal blooms and other aquatic plant growth. In addition there is a concern about fish diseases and genetics, which may be the consequence of the interaction of fish raised in Great Lakes net pens and native fish in the surrounding environment.

Discussing environmental issues

To address these concerns Michigan Sea Grant was invited to speak at the 28th Annual No-Spills Conference in January 2018, to discuss environmental issues surrounding net-pen aquaculture in the Great Lakes. Currently there are seven net-pen aquaculture operations that exist in northern Lake Huron on the Canadian side of the lake. These operations are sustainably producing more than 5,000 tons of rainbow trout per year with some being sold in retail markets in Michigan. They provide 340 direct and indirect jobs with a $100 million contribution to the Canadian economy. These net-pen aquaculture operations take up a small footprint in the environment; one of these operations that produces 500,000 pounds of rainbow trout per year would fit into an average size Michigan marina.

Fish disease risks and genetic dilution can be minimized

For Great Lakes net-pen aquaculture to be environmentally sound it must have practices that prevent disease transmission and escapement of fish into the wild, as escapees could affect the genetic integrity of surrounding fish populations. These operations must also be non-polluting with minimal and recoverable impacts. With regards to fish diseases, the commercial aquaculture industry is highly regulated and is held to the same standards as state and federal hatchery programs. Fish disease risks are minimized and prevented through regulation, biosecurity, and best management practices.

In 2014 the state of Michigan stocked more than 20 million fish, produced from gametes collected from wild fish. This equated to 325 tons of fish stocked, 9 different species, 370 stocking trips, 732 stocking sites, with 100,000 miles of travel from several fish hatcheries. In comparison Canadian net-pen operations in Lake Huron typically stock one cohort, certified as specific pathogen free, then raise the fish to harvest and truck them one way to a fish processing facility. The net results are that Michigan hatcheries have a much higher risk of disease transmission than the current system for growing trout in Canadian net pens.

The Great Lakes already have rainbow trout which are non-native to the region. They were introduced by fishery management agencies years ago and many of these fish are now naturalized, spawning on their own in local rivers, with additional enhancement from government fish hatcheries. Rainbow trout produced in Great Lakes net-pen operations can be female triploids which are sterile and will not reproduce should they escape into the environment. So the risk of genetic dilution can be eliminated by use of these female triploid rainbow trout.

Low phosphorus, digestible fish diets help minimize phosphorus waste

During the height of the Great Lakes net-pen aquaculture discussion there were media reports that a typical net-pen operation with 200,000 fish would produce as much waste as a city of 65,000 people. In reality a city of 65,000 people would produce 21 times more fecal matter than a 200,000 fish net-pen operation. This same city would produce 5 times more phosphorus compared to the net-pen aquaculture operation. The city would also generate 24 kg/yr of E. coli with none coming from the net-pen operation.

Canadians have had net-pen aquaculture operations in their northern waters of Lake Huron since 1982. To help address the issue of excess phosphorus discharge from freshwater net pens, Fisheries and Oceans Canada completed a study on Freshwater Cage Aquaculture: Ecosystems Impacts from Dissolved and Particulate Waste Phosphorus. Fish receiving digestible phosphorus in specific amounts to meet their growth requirements excrete only small amounts of dissolved phosphorus. Dissolved phosphorus is most often the form of concern in impaired waters. The other form of phosphorus excreted from fish is particulate phosphorus which settles to the bottom sediments. The particulate phosphorus which accounts for the majority of the waste from net-pen operations is transported to the bottom sediments and is not immediately available for uptake into the ecosystem. In sediments it can be consumed by the benthic organisms and enter the aquatic food chain. Both dissolved and particulate phosphorus wastes produced by fish are the results of the diets they consume. The development of low phosphorus, highly digestible diets has been a tool to help minimize phosphorus waste by aquaculture operations.

The Fisheries and Oceans Canada study found that based on net-pen aquaculture production in northern Lake Huron in 2006 contributed about 5 percent of the annual total phosphorus loading to the North Channel. The study concluded that the likelihood of phosphorus additions to the environment from net-pen aquaculture operations resulting in eutrophication to Canadian freshwater environments under the current level of fish production can generally be characterized as “low.” The greatest concerns for phosphorus are in the nearshore areas where excess aquatic plant growth can foul the shorelines. In contrast, offshore phosphorus loading is of less concern and higher phosphorus concentrations may be considered a means to help mitigate declining populations of forage fish and the poor condition of sport and commercial fish species.

New book about amphibians and reptiles a good read

“Amphibians and Reptiles of the Great Lakes Region, Revised Edition” offers readers a glimpse into the world of herpetofauna

An American Toad is one of the Great Lakes amphibians featured in a newly revised book. Photo: Mary Bohling, Michigan Sea Grant

An American Toad is one of the Great Lakes amphibians featured in a newly revised book. Photo: Mary Bohling, Michigan Sea Grant

Growing up in Michigan, I recall encounters with some special amphibians and reptiles including Spring Peepers in the Les Chenaux Islands, Eastern Fox Snakes along the Lake Erie shoreline, Mudpuppies, and Blanding’s Turtles in the Detroit River and American Toads on Isle Royale. Recently I read a newly revised edition of the book, “Amphibians and Reptiles of the Great Lakes Region,” by James H. Harding and David A. Mifsud, which helped me learn even more about the creatures I’ve seen over the years.

The book includes range maps, photos and other key information for each reptile and amphibian species known to occur naturally within the Great Lakes basin along with limited information for marginal and questionable species. Also included are definitions to help readers understand these often mysterious and misunderstood species.

Are you a herp-watcher?

Readers will learn that herpetology is the scientific study of amphibians and reptiles while herpetofauna is used to describe amphibians and reptiles occurring in a defined geographic area, and that amphibians include frogs, toads, salamanders and caecilians and reptiles include turtles, tortoises crocodilians, lizards, snakes and tuatara.

The concept of “herp-watching” (think bird-watching but substitute animals with feathers for those with scales, slimy skin or shells) is also discussed. This recreational hobby offers an alternative to keeping amphibians and reptiles as pets. Herp-watchers can also play an important role in protection and conservation by documenting observations using web and mobile apps such as the Michigan Herp Atlas.

Management strategies considered

The conservation section for each species explains the animal’s relationship with humans such as economic importance, population trends, threats posed by human activities and possible management strategies. One of the things I found interesting in the habitat and ecology section was the feeding behaviors of some of the species, particularly those that rely on smell and sound to detect prey. I especially liked reading about the Kirtland’s snake because, although its range includes where I live in southeast Michigan, I had never even heard of the species. This little secretive snake lives most of its life below ground in burrows constructed by other animals or under leaf piles, rocks and logs and can flatten itself and become immobile when threatened.

Harding and Mifsud have compiled a wealth of herpetofauna information of use as a reference to non-specialists as well as professional herpetologists. I would recommend this book to anyone with a curiosity about or passion for amphibians and reptiles.

MSU prof seeks crowdfunding support for Great Lakes fish diet research

You can be a part of this important study by donating to support student researchers analyzing stomach samples from Lake Michigan and Lake Huron.

As we all know, the Great Lakes have changed a lot in the last decade or so. Alewife have declined, round goby are increasing, and lake trout and walleye continue to recover. Chinook salmon, the heart of Lake Michigan’s fishery, have fluctuated in numbers in the past few years, and have collapsed in Lake Huron. Our fisheries agencies must make informed decisions regarding stocking and levels to support both fisheries and conservation goals. These decisions are based in part on what those predators are eating. What predators eat is an excellent indicator of ecosystem health, and can help tell us how sustainable the fishery is.

With the tremendous help of recreational anglers, MSU together with state, federal, and tribal agencies have collected nearly 2,000 predator stomachs from around Lake Michigan and Huron. We need help to be able to analyze all of them, particularly those from Lake Michigan. MSU has a wealth of potential help in terms of undergraduate students eager to gain valuable research experience. However, funding is needed to pay these students for their work.

Would you help by contributing to this research effort?

With the help of MSU CrowdPower, any donations made at the website will go directly to the predator diet study. Any donation will help, and all donations are tax deductible.

Want to stay up-to-date on the project? 

We have several other ways to connect including:

Ludington Regional Fishery Workshop

Event Date: 1/13/2018

January 13, 2018

West Shore Community College
3000 North Stiles Road
Scottville, MI 49454

Details

Lodging

There is a block of room secured at the Ludington Holiday Inn Express for the night of January 12th. Double rooms are $75/night and are first come first serve. 

Group Code: MSU
Group Block Name: Fisheries Workshop
Reservations: (231) 845-7311

Michigan Fish Producers Association Annual Conference

Event Date: 1/27/2018

Michigan Sea Grant will be coordinating a daylong, educational program on current issues affecting the Great Lakes commercial fishing industry.

The program will run from 9:00 a.m. through 4:00 p.m. on Saturday, January 27, 2018 as part of the Michigan Fish Producers Association Annual Conference at the Park Place Hotel in Traverse City.

There is no charge for attending this event. For additional information please contact Ron Kinnunen at (906)-226-3687 or kinnune1@msu.edu.

See: MFPA Agenda

DNR seeks comments on Lake Michigan management plan

Event Date: 11/28/2017
End Date: 11/30/2017

November meetings in Manistique, Traverse City, and Grand Haven to share details and solicit input on proposed plan.

DNR seeks comments on Lake Michigan management plan

Fishing in Lake Michigan has had its share of ups and downs. A steady stream of invasive species led to several big changes in the lake. Sea lamprey destroyed the lake trout fishery in the late 1940s, leaving the door open for an explosion of alewife that died off en masse and became the plague of beachgoers in the early 1960s. Stocking of non-native Chinook and coho salmon created a world-class recreational fishery in the late 1960s. Fishery managers have been trying to maintain an optimal balance of predators and prey since salmon declines due to bacterial kidney disease (BKD) in the 1980s. With the explosion of new exotics like quagga mussel and round goby and decreases in open water nutrients over the past twenty years, old assumptions about the lake’s productivity are being revised.

All of this makes management a difficult proposition. States and tribes around Lake Michigan serve on the Lake Michigan Committee, which adopted Fish Community Objectives (FCOs) in 1995. The lake has changed a lot since then, and some key objectives (like total harvest of all salmon and trout species) have fallen below target levels in recent years.

Individual states have worked within the framework of the FCOs. In the past, states have accomplished this on a species-by-species basis. Now Michigan Department of Natural Resources (DNR) is working to develop a more comprehensive and holistic approach to managing the lake.

Visit the Lake Michigan Management plan website to view the draft plan and submit comments online.

What to expect

The agenda for the public meetings includes:

  • Brief overview of management plan and how to comment.
  • Brief overview of zonal management.
  • Describe and discuss stocking options.
  • Have participants pick their most preferred option.

Meeting times and locations

Three meetings are planned:

  • November 28, 2017: 6:30 p.m.-8:30 p.m., Comfort Inn Conference Room, 617 E. Lake Shore Dr., Manistique, MI 49854
  • November 29, 2017: 6:30 p.m.-8:30 p.m., Boardman River Nature Center, 1450 Cass Road, Traverse City, MI 49685
  • November 30, 2017: 6:30 p.m.-8:30 p.m., Loutit District Library, 407 Columbus Ave., Grand Haven, MI 49417

Lake Michigan’s charter fishing industry is… remarkably stable

It doesn’t make for sensational headlines, but charter fishing has been a consistent part of coastal tourism despite recent ups and downs in fishing success.

Unhooking a Chinook salmon on the deck of a Lake Michigan charter boat. Lake Michigan charter trips and salmon remain a big draw and consistent part of coastal tourism. Photo: Michigan Sea Grant

Unhooking a Chinook salmon on the deck of a Lake Michigan charter boat. Lake Michigan charter trips and salmon remain a big draw and consistent part of coastal tourism. Photo: Michigan Sea Grant

For the past 10 years as a Sea Grant Extension Educator I’ve worked to understand the economic impact of Michigan’s charter boat industry. This has big implications for coastal tourism. In 2016, charter fishing generated $23 million in Michigan’s coastal communities, resulting in 476,361 employment hours. Lake Michigan’s charter fishery is the largest, accounting for around 70 percent of the state’s charter fishing effort according to Michigan DNR. Charter captains in Michigan report their catch and effort to DNR, and Michigan Sea Grant uses this information to calculate economic impacts and investigate trends.

Big salmon are a big draw

Last year was a tough one for fishing. The Chinook salmon is a prized species on Lake Michigan, and charter harvest rate of Chinook salmon fell to the lowest it has been since 1995, when bacterial kidney disease (BKD) wiped out many of the lake’s salmon. According to Michigan DNR, charter harvest in Michigan waters of Lake Michigan ranged from 1.09 to 1.94 Chinook salmon per trip in the early 1990s, ranged from 2.24 to 7.40/trip 1996-2014, and fell from 2.27/trip in 2015 to 1.94/trip in 2016.

This understandably caused a lot of concern among charter captains last year. Angst was compounded by plans to reduce stocking, although the goal of the stocking cut was to prevent a complete crash in the fishery. Some of the debate centered on which species to cut: lake trout or Chinook salmon.

A recent study funded by Wisconsin Sea Grant found that Wisconsin anglers on Lake Michigan are willing to pay more to target Chinook salmon ($140/trip) vs. lake trout ($90/trip). An earlier study on the Lake Huron charter fishery found that the decline of Chinook salmon catch rates was linked to a 51 percent drop in charter fishing effort and resulting economic impacts, although increasing gas prices in the late 2000s were also a factor. During the Lake Huron charter fishing crash of the mid-2000s lake trout catch rates remained high. But what does this all mean for Michigan waters of Lake Michigan?

Consistent economic impacts are the rule

Despite low Chinook salmon catch rates in 2015 and 2016, charter trips and resulting economic impacts did not exhibit the same kind of crash that occurred in Lake Huron around 2004. In fact, Lake Michigan charter trips remained above the post-BKD average of 11,577 trips/year in 2015 and 2016 according to Michigan DNR.

2009 charter economic study found that the economic impact of charter fishing around Lake Michigan averaged $14 million; due to economic factors (e.g., rising gas prices, recession) this fell to $11.6 million in 2009. After adjusting for inflation, this means that Lake Michigan charter fishing generated an average of $15.7 million in Michigan and bottomed out at $12.6 million in 2009. In 2016, Michigan Sea Grant found that Lake Michigan charter fishing generated $15.7 million in economic impacts for Michigan coastal communities. Dead on average, despite the low Chinook salmon harvest rate.

Few fluctuations relative to Huron

The fact of the matter is that Lake Michigan’s charter fishery has been much less volatile than Lake Huron’s, both in terms of harvest rates and economic impacts. While Lake Michigan harvest rate dropped to just under two Chinook salmon per trip in 2016, Lake Huron crashed to fewer than one Chinook salmon every two trips (Michigan DNR data) and economic impacts of charter fishing fell by more than 50 percent.

In other words, anglers could still expect a good chance that their boat would harvest a Chinook on Lake Michigan last year while this was not the case after the decline of salmon on Lake Huron. Other species (including lake trout, coho salmon, and steelhead) play an important role in the charter fishery, too. Many anglers are thrilled to catch any of our Great Lakes trout and salmon, all of which make good eating and top out at an impressive size.

Given the recent troubles with predator-prey balance in Lake Michigan and the high prey consumption of Chinook salmon, we can expect a more diverse mix of predators in the future along with modest Chinook catch rates. The good news is that the economic impacts of Lake Michigan’s charter fishery appear to be quite stable so long as anglers can still expect a reasonable chance at boating a ‘king.’

Lake Michigan kings are back — but why?

After the gloom-and-doom of 2016, anglers are gearing up for a much better run of salmon in 2017. Recent trends in the fishery suggest that ups and downs may be the new norm if prey populations do not stabilize.

Chinook salmon from the 2014 year-class are now Age 3 and they seem to be providing very good fishing in Lake Michigan.

Chinook salmon from the 2014 year-class are now Age 3 and they seem to be providing very good fishing in Lake Michigan. File photo: Michigan Sea Grant

Spread the word!  Lake Michigan kings are back — for now.

After a couple of disappointing years of fishing for Chinook salmon along the Michigan shoreline of Lake Michigan, anglers are once again excited about the late-summer bonanza that these “king” salmon provide. While the final estimates of angler harvest and catch rates will not be available from Michigan DNR and other agencies until spring, the long lines of heavy coolers at fish cleaning stations and full boards of fish are a very good sign.

The size of fish is even more impressive. Ever since bacterial kidney disease (BKD) ran through the Chinook salmon population in the late 1980s, king salmon over 30 pounds have been rare to nonexistent in most years. This year has already produced numerous 30 pounders and even one giant that tipped the scales at 41.48 pounds (see details).

Why the rebound?

While fisheries scientists do not have a definitive answer to this question, there are several factors that at work. Many relate to the poor year-class of Chinook salmon in 2013. Many anglers will remember the public process that led up to the 46 percent reduction in Chinook salmon stocking for 2013. On top of this stocking cut, natural reproduction fell by an estimated 84 percent in 2013. All told, the number of Chinook salmon entering Lake Michigan dropped from 10.68 million in 2012 to 3.5 million in 2013.

This weak 2013 year-class was a big factor in the poor fishing experienced last year because Age 3 fish from the 2013 year-class were returning to spawn in 2016. The good news is that wild reproduction increased slightly in 2014 and the total number of Chinook salmon increased to 6.47 million (stocking remained steady from 2013 to 2014).

Chinook salmon from the 2014 year-class are now Age 3 and they seem to be providing very good fishing. Fisheries managers have been trying to balance the number of predators and available prey for decades, and judging by early reports it seems that the current balance is providing a nice mix of good catch rates and large, healthy salmon. However, this does not mean that the future of the Lake Michigan fishery is secure.

Ups and downs may be the new norm

Growth of salmon has been bouncing up and down like a ping pong ball over the past decade. The growth rate of fish is a good indicator of their overall well-being and ability to find enough food, so this means that conditions are changing a lot from one year to the next.

Fisheries managers look at the weight of mature Age 3 female Chinook salmon returning to weirs and harbors as a standardized measure of salmon growth in Lake Michigan. In 2015, the average weight of an Age 3 female was 13.1 pounds. This increased to 19.0 pounds in 2016. That is a huge difference!

Such radical and rapid shifts in growth rate indicate instability in the ecosystem. In other words, food availability is changing a lot from one year to the next. Some of this is related to changes in the number of predators (especially the big fluctuations in wild Chinook salmon production) but fluctuations in the availability of alewife (the salmon’s food source) are a bigger problem.

In short, small alewife are relatively abundant in some years and provide a lot of food for salmon. In other years, alewife do not produce as many young and salmon have trouble finding food. A big problem in recent years is that alewife do not often survive to spawn several times. Instead, nearly all alewife are eaten before they reach Age 5.

Not coincidentally, the last really good alewife year class we had was in 2012. The alewife from that 2012 year-class are now Age 5. If some of them are able to avoid all of the hungry mouths out in the big lake until next year then we may finally have some Age 6 alewife in Lake Michigan once again.

This would be a good sign for overall stability of predator-prey balance in the lake, but it is by no means guaranteed. Prior to 2000, alewife of Age 6, 7, and 8 were fairly common and in some years Age 9 alewife were also found. We are still a long way from that level of stability in older alewife.

Judging by recent history, the boom times will not last long. Get out there and enjoy it while it lasts, and remember the good times next time we have a tough season.

Students team up with Michigan Sea Grant to protect native fish

A threatened fish called the River Redhorse is the latest subject of the Native Fish Heroes poster series.

The River Redhorse suffers from a case of mistaken identity. Even though it is a native fish that requires clean flowing rivers, many people mistake the River Redhorse for invasive carp or other native suckers that can tolerate polluted water. In fact, the River Redhorse is listed as a threatened species in Michigan and is only found in a handful of large, rocky rivers.

Students participating in the Lakeshore Environmental Education Program (LEEP) at Walden Green Montessori School in Ferrysburg had a chance to get to know the River Redhorse this spring. They learned how to identify closely-related species and teamed up with Michigan Sea Grant to teach others why the River Redhorse is so rare.

Guilt by association

The River Redhorse is one of six species of redhorse sucker living in Michigan waters. Some of the other species are very common, and fishing regulations allow for unlimited harvest of other sucker species using a variety of gear including spears, bows and arrows, certain types of nets, and hook-and-line. Suckers are bony but very good to eat when canned or ground. Unfortunately, the River Redhorse is easily mistaken for other species and is sometimes harvested along with other sucker species.

Worse yet, some people mistakenly believe River Redhorse are a harmful or invasive species. They get to be fairly big (over 30 inches long) and could be confused with invasive common carp. Perhaps this is one reason why River Redhorse are sometimes left on the bank to rot.

River Redhorse need clean-swept rocky areas to spawn. Many large rivers suffer from pollution in the form of silt and sand that washes in from eroding banks, city streets, and agricultural land. This “nonpoint source” pollution can smother eggs and also harms native filter-feeding mussels. The River Redhorse feeds heavily on native mussels, and the decline of mussels in many areas of the eastern United States may be one reason for the rarity of River Redhorse.

Big rivers are also subject to development for flood control, navigation, and hydro power.  Channelization removes important shallow-water spawning area and dams restrict the movement of fish. This can block River Redhorse from reaching historic spawning grounds, but some dams also restrict the movement of harmful invasive species.

Even though River Redhorse are not common anywhere, there are three Michigan river systems that still provide good habitat and support breeding populations: the Muskegon River, St. Joseph River, and Grand River.

Students at Walden Green attend school near the mouth of the Grand River, one of the last places in Michigan to find River Redhorse. By highlighting threats and suggesting ways that people can help to keep our rivers clean, the students hope to help protect this local treasure. They even came up with a “Rockin’ River Redhorse” theme poster, which emphasizes the fish’s need for clean, rocky habitat.

The River Redhorse poster is the second in Michigan Sea Grant’s Native Fish Heroes poster series. The Lake Sturgeon was the first poster created, and other teachers around Michigan have expressed interest in tackling Cisco, Smallmouth Bass, and Burbot. If you teach at a K-12 school and have a local connection to one of our fascinating native fish species, contact Michigan Sea Grant for additional details.

Download poster Big rivers, big problems