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March 2, 2018

Wisconsin’s Rare and Endangered Fish


The Wisconsin basin consists of three main drainages; Lake Superior, Lake Michigan and the Mississippi River. It is home to over 160 fish species, most of which are rare and endangered. It is home to unique fish species and as a result, most of its species are listed in the natural heritage working list. These species have become rare because of a combination of several factors. The factors include habitat degradation, habitat loss, disturbance sensitivity, exploitation, genetic problems, predation, parasitism, and competition. Some of the rare species found in this basin are located along the edge of their main ranges. Climate change and invasive species also profoundly impact on the rare species and is expected to become even one of the most significant factors in the future. The reason why the fish species and other animals are unique to Wisconsin is the vibrant ecosystem that has diversity and availability of their food and the excellent climate that allows these animals to thrive.

Some of the rare fish species in the Wisconsin basin according to Dave Bosanko (2007), include the skipjack herring, lake sturgeon, yellow perch, catfish, pumpkinseed, salmon and trout, and smallmouth bass. Others include the white bass and rock bass bullheads, northern pike, wallet western sand darter, American eel, cisco, short jaw cisco, crystal darter, blue sucker and gravel chub. The lake chubsucker, mud darter, bluntnose darter, least darter, banded killifish, star head topminnow, goldeye, pallid shiner, black buffalo, longear sunfish, striped shiner, redfin shiner, shoal chub are also some of the unique species. The list also includes species such as the river redhorse, black redhorse, pugnose shiner, Ozark minnow, slender madtom, gilt darter, paddlefish and Pygmy whitefish among others. In this document, we will be discussing some of these rare fishes, their description, distribution, spawning, and angling.

Skipjack Herring

Scientifically referred to as Alosa chrysochloris, this unique fish species, according to Becker, George (1983), is very bright silver, but their backs are darker, and the tips of their jaws contain black pigments with around 1-9 black spots on their upper sides. The most visible of these spots are found just directly behind its gill opening. They have a long body and are laterally compressed. The mouth is large and terminal and extends below the middle of the eye. Their dorsal fins are placed directly above their pelvic fins, and just like all the other Alosa species, they lack the dorsal ray of the Dorosoma species. Their bellies’ single rows of scales are folded over the edge giving the belly a seemingly sharp saw-like edge. The only difference between the skipjack and the alewife is that it has a larger mouth and its body is more elongated. They belong to the Clupeidae family. The skipjack grows to between 12-16 inches in adulthood but can also reach 21 inches with 3.5pounds.

The skipjack herring are known to spawn between May and July and their spawning period can be prolonged. It is a freshwater fish mostly found in larger rivers. During high tide, they avoid high waters by congregating in the clearer waters and creek mouths, and they feed primarily on small fish channel shiners and mainly emerald. This fish has almost become extirpated in Wisconsin, and its re-establishment is underway. (Dave Bosanko, 2007).

Lake Sturgeon

It is scientifically referred to as Acipenser fulvescens and is one among the 25 sturgeon species (Dave Bosanko, 2007). The lake sturgeon’s taste buds are situated on the rubbery and the prehensile lips. These sensory organs help the lake sturgeon to locate its bottom-dwelling prey.  It has no teeth thus it vacuums up its food and swallows whole. It mostly feeds on live insect larvae, metazoan organisms, and worms including leeches. The lake sturgeon is an evolutionary bottom feeder. Its shape is streamlined, and its skin bears rows of bony plates on both the back and the sides. The fish has an elongated spade-like snout that it uses to stir up sediments and substrates at the lake bottoms and river beds while feeding. The lake sturgeon grows up to 7.25ft and weighs over 240lb.

Lake sturgeons live long; approximately 55 years and only reach sexual maturity after ten years. They reproduce by swimming in circles around each other and shaking vehemently. The male will only stop circling when he has released the fertilizer, and the female lays her eggs. In Wisconsin, the lake sturgeon is rare and has been going through an effort of restoration. The USFWS takes the following measures while restoring the lake sturgeon: distribution, recording abundance, age, the health of the species and growth. It, however, will take years to confirm if the fish has started to naturally produce due to its extended period before it reaches sexual maturity (Dave Bosanko, 2007).

The lake sturgeon were once targeted as a nuisance bay catch for damaging fishing gear and later targeted by commercial fishermen when their eggs and meat became prized. Their catch rates have faced many environmental challenges including flood measures, pollution and dam construction. The sturgeon upon returning to the lakes and rivers in which they were born in to spawn every spring found spawning shoals destroyed by deposition of silt from lumbering and agriculture as well as blocked tributaries thus threatening their existence.

Yellow Perch

Scientifically known as Perca flavescens, the yellow perch according to Becker, George (1983), is found in all the three drainage basins in Wisconsin; the Mississippi River, Lake Michigan and Lake Superior. It’s a glacier lakes species, widely distributed except in southwest Wisconsin. This is a native fish with two dorsal fins that are separated into soft-rayed and spiny portion; it has yellow sides, has no canine teeth and has seven blackish bars on the sides.

They are members of the perch or the Percidae family, and due to their reputation of having tasty meat, they have become the most frequently caught game fish in Michigan and precious addition to the products of the great lakes. They mostly prefer the shallow waters not more than 30 feet deep. Given a choice, they prefer to live at 66-70 degrees Fahrenheit water temperature. Perch adult average length is 10 inches with a weigh between four to ten ounces. Despite the varying adult size, the yellow perch is a prolific breeder. Its size and growth ultimately depend on habitat productivity and population density. Overcrowding causes stunted growth of the yellow perch, and they may not grow beyond 6 inches in adulthood thus a controlled harvest program is recommended. This benefits both the fish and the anglers. (Dave Bosanko, 2007).

The yellow perch reach their sexual maturity at four years for the female and three years for the male.  They usually spawn in April after ice out and early may when the water temperatures are between 45-52 degrees. The spawning coincides with that of the suckers and is closely followed by the walleyes spawning.  The yellow perch do not construct nests but lay their eggs in gelatinous strings over the fallen trees in the shallows, roots and dense vegetation.

The yellow perch are bottom feeders that bite slowly and deliberately. They eat almost everything although their favorites include planktons, minnows, insect larvae, and worms.  The yellow perch remain active all winter under ice offering the ice anglers great opportunity to catch them. Tackles used in capturing the yellow perch ranges from a fly rod or a simple hand line in summer to a short jigging and whippy rod in winter.  The yellow perch moves in schools numbering up to their hundreds. The spawning areas provide the ground for the best perch fishing (Slow Sprint, 2010).


According to Slow Sprint (2010), the walleye is a freshwater fish, scientifically referred to as Sander vitreous. The walleye species was initially confined in the more extensive waterways and the vast lakes of Wisconsin. There was an excessive restocking of the walleye fingerlings and fry that occurred early in the Wisconsin waters and partly obscured the species original distribution.

The walleye spawning migration according to Dave Bosanko (2007), begins when the water temperatures hit between 38-44 degrees Fahrenheit soon after the ice goes out. Their spawning occurs between April and May. The breeding reaches its peak ordinarily when the water temperatures are between 42-50 degrees Fahrenheit. The walleye broadcasts its eggs and does not exercise any parental care making it a non-territorial fish during spawning.

Walleyes feed primarily on minnows although small bullheads, leaches, small plugs and night-crawlers fall in their favorite bait feeds. They stay in deep, clear waters during the day and move into the shallow waters at night. In turbid waters, walleye can be caught any time of day, and they are the most highly prized game fishes in Wisconsin. Even in murkier waters, the walleye is good at hunting small fish.

Walleyes are yellowish gold and dark olive. They have a spiny dorsal fin and many sharp teeth. The characteristic that most distinguishes them is their unusually large marble like eyes that help them efficiently locate their prey by reflecting light while hunting at night. They grow to about 35 inches and weigh 20 pounds in their adulthood. It is important to note that the walleyes grow much faster in warmer climates and their lifespan rarely exceeds ten years. In the cold waters, the walleyes grow much slower and can reach up to the age of 20 years. The bigger sized Muskies and the northern pike are the most probable walleye predator. Walleyes in Wisconsin are caught using the following fishing methods: jig and live bait combination, bottom bouncer and spinner combination, slow death, swim baits and casting crank baits onto windy, shallow rock structures. (Dave Bosanko, 2007).

Walleye fishing is fun, but the fight has not made it enjoyable, but it is the challenge of finding the best way to lure then and the presentation that makes them strike. Walleye is a wily fish and has tricks up its sleeve when hiding. The rewards of the search are worth it especially if you were looking to eat the catch since the walleye is one of the best tasting freshwater fish in Wisconsin. They are nocturnal and so fishing at dawn, dusk or night offers the best chances for landing a catch. The one thing that excites anglers about fishing the walleye in the fresh water is reeling up the walleye and seeing its eyes flash as it approaches the surface.

American Eel

The American eel according to Becker, George (1983), is also referred to as the Anguilla rostrata. It is a slender snakelike fish and is covered with a mucus layer making it appear slimy and naked despite it having minute scales. It has a long dorsal fin that continuously runs from the middle of the back. The dorsal fin is similar to the ventral fin. Its pectoral fin is located near the midline and is relatively small, and it has no pelvic fins.  The American eel varies in color from brown shading, olive green, greenish yellow and white or gray belly. Eels living in clear waters are often lighter than those residing in tannic, dark acid stream.

The American eel prevails in fresh water but enters the Atlantic Ocean for the spawning migration to the Sargasso Sea. The spawning takes place away from the shores where the eggs hatch. A female American eel lays up to 4million buoyant eggs and dies immediately after egg-laying.  The early stages larva develops into the leptocephali which move towards North America morphing into glass eels and reentering the fresh water system of the Wisconsin basin. Here they grow into yellow eels until they are old enough to begin the migration once more, (Slow Sprint, 2010).

American eels according to Schmidt, J. (1922), are bottom dwellers and hide in tubes, burrows, masses of plants and snags. During their freshwater stages, they are found in rivers, streams, silt-bottomed lakes, as well as coastal bays, oceanic waters, and estuaries during migration and spawning. They burrow themselves in mud during winter and enter into the torpor stage which is the stage of total inactivity when temperatures go below 5 degrees C. the American eels life cycle has six stages namely the eggs – leptocephali  -glass eels – elvers- yellow eel- silver eel. They have an excellent sense of smell, and they depend on it to find food.

Scientists have raised concerns on the dwindling American eel population which has dropped to dangerously low levels. Biologists are doing their best trying to unearth how specific factors are affecting the American eel’s population, but their elusive nature makes it hard for them to capture and get crucial life history information and data from the eels.

It is however evident that the complex life and most especially specific stages pose broad ranges of threats, for example, being a catadromous the productivity of the eel is solely dependent of free downstream passage for their spawning migration. Considering the dams and the human-made barriers erected on the rivers, we can then agree that this is no smooth sailing and it decreases diversity and habitat availability. Their productivity is also dependent on the availability of different habitations allowing growth and maturation, (Dave Bosanko, 2007).

The eel’s sex ratio in the population is also a big problem this is because the females and the males live in different habitats and an impact on one region can greatly affect the other regions numbers. They are also very sensitive to oxygen that is poorly dissolved, and contamination from heavy metals like dioxins and chlordane and also pollution can cause reduced productivity due to the serious toxicity. Construction of agricultural facilities and dams is detrimental to the habitats diversity and availability; dredging affects their population distribution, migration, and availability of prey. Excessive harvesting and overfishing of juvenile eels affect their local population. Other natural threats include interspecific competition, parasites, and pathogens and changes the oceanographic conditions, (Schmidt, J. 1922).


Cisco is also known as lake herring and scientifically referred to as Coregonus artedi. It is a member of the salmon and the trout family. It inhabits the middle water regions in the great lakes and the inland lakes. Its body is long and elongated with two dorsal fins. The Cisco has a long lower jaw with a pointed snout, (Dave Bosanko, 2007), and the side view is decidedly elliptical. They have iridescence on their sides which are a faint purple to pink, blue-green to grey backs and their below is white. The color on the fins varies, and generally, the caudal and the dorsal fins are darkly pigmented.

The Cisco form spawning schools once the temperatures drop in the fall. This happens to be in the months of late November and early December. They begin to spawn once surface ice begins to form, and they spawn at a depth of three to ten feet deep or even more in-depth. The male gets to the spawning ground first and leaves before the females. Eggs are then deposited at the bottom and abandoned. They develop slowly in the low temperature and when spring breaks up the surface ice they hatch. The fry feed on zooplankton and small insects as well as algae. The male and the female then grow at the same rate with the females living longer and on average reaching a larger size than the males. The average weight an adult can achieve is less than a pound, but in some waters, the Cisco grows to larger sizes and may even reach and exceed five pounds.

Cisco is however preyed on by the larger northern pike, lake trout, walleyes and yellow perch. The Cisco’s are a crucial part of the great lakes ecosystem and its food chain. In the 19th and the 20th century, the ciscos were a significant part of the great lakes fishery, but the numbers have since then drastically dropped. They are mostly caught by the anglers in the fall when they gather in their spawning schools, (Slow Sprint, 2010).

The Cisco is a cold water fish and is likely to be found in the deep lakes with good water quality. The population may have declined due to biotic interaction by the invasion smelt, the loss of the oxy-thermal habitat by land use changes, climate variation and eutrophication and decline in the gillnet catch rates. Difficulty in modeling its extirpation and tan acute extirpation event can mark longtime environmental conditions, (Wisconsin DNR, 2007).


The Goldeye according to (Slow Sprint, 2010), is a unique fish with huge eyes and large sharp teeth. It’s a very bright silverfish, its large eyes have a gold coloration on the iris, and it has sharp teeth on its jaws and tongue. Its dorsal fin has around ten rays and starts just behind the anal fin front edge. The Goldeye has a pointed edge or a fleshy keel on their belly. The edge is found between the pectoral fins, and it goes all the way to the anus. The Goldeyes gold coloration on the iris, elongated body, the more extended keel on the body and the dorsal fin that starts behind the anal fins front are the only differences between a mooneye and a Goldeye. They are nocturnal, and their eyes are adapted to the dim lights of their turbid habitat, (Becker, George, 1983).

The Goldeye comes from the Hiodontidae family it’s also referred to as the bony tongue. Its scientific name is Hiodon alosoides. The adults grow up to an average 17 inches but can reach 20 in good waters. They averagely weigh between 1-2 pounds, but in good waters, and they can reach 3 pounds. The Goldeye prefers large rivers for habitat, and they are tolerant to the turbid waters and the clay silts. They cannot, however, tolerate chemical and industrial pollutants. They are either found below dams or in the areas with swift currents. Due to its tolerance to the turbid waters, it was found in abundance more than its close relation the mooneye. It feeds on small aquatic invertebrates and small fish like the grasshoppers, fireflies, moths, mollusks, crustaceans, shrews, frogs, trout perch, mice, perch, and darters

They are known to spawn in late March and early April min areas with swift currents allowing their eggs to keep drifting in water until they reach the hatching maturity. Research has shown that today. They are mostly found in the Mississippi River, lower Wisconsin, and lower Chippewa River. Their population has dramatically decreased in the recent years, and the main reason for this decline is the quality of water that has deteriorated in the upper Mississippi river due to chemical and industrial pollutants. They are also targeted and preyed on by the walleyes, the northern pike, mammals, and birds, (Dave Bosanko, 2007).

Longear Sunfish

The Longear, according to Slow Sprint (2010), is scientifically referred to as Lepomis megalotis, from the Centrarchidae family. It’s a deep bodied, thin sunfish, flexible with an opercula ear flap are more elongated as adults. They have a variety of coloration that includes black olive to rusty brown, and its belly and breast are yellow to orange-red, with lighter sides. Its sides and back have specks of orange, yellow, blue, and emerald. Breeding males are bright orange below and iridescent green above, and their pelvic fins are blue-black while the ventral fins are rusty orange. As adults, the Longear sunfish can grow between 2.8- 3.7 inches.

The Longear sunfish according to Wisconsin DNR (2007), prefers a habitat with moderate aquatic vegetation, clear, shallow and still stream waters, lakes, and rivers at average temperatures. They feed on aquatic insects, fish eggs microcrustaceans, mites, mollusks, small fish and filamentous algae extensively found at the water surfaces.  They are mostly located in the northeast, south-east and east-central Wisconsin mainly in Lake Michigan and Mississippi River drainage basins.

They spawn during peak water temperatures in June all through August. Their males build nests in hard mud or sand and defend the territory. Their eggs hatch within five days and the offspring reach sexual maturity within the second or third summer. Their population is too sparse to compete with other fishes or even become their prey. Their existence is mostly threatened by big agriculture projects going on in the area where water pollution is inevitable. They are also intolerant to turbid water. Young anglers love to keep them as pets. They resemble other sunfishes, and it’s hard to differentiate them, (Becker, George, 1983).

Redfin shiner

Scientifically known as the Lythrus umbratilis is a member of the minnow family (Cyprinidae).  According to Becker, George (1983), its coloration is light olive to steel blue with a reddish tint in breeding males and silvery sides. They have a small dark spot at the base of the back dorsal fin. They also have a blunt snout, and their eyes are large. Like all the other minnows, the redfin shiner is a crucial link in the freshwater ecosystem and its food web. They usually eat algae and insects, and they are in turn consumed by wading birds, larger fish, and turtles. They inhabit and can survive well in turbid waters that are laden with silt but not during the breeding season. Many people refer to any small fish as minnows. However, only the Cyprinidae family are real minnows. The members of this family include the shiner, dace, chub, and the stone-roller. The goldfish found in Asia are also members of this family. North America has 231 species of the minnows.

They reach their sexual maturity in the second or third summer after hatching. They spawn from the end of April all through to August. They nest their eggs on previously used sunfish nests and live for a maximum of three years. The scent of the fluids that had been released by the sunfish during their spawning attracts the redfin shiners that congregated in large schools near the surface. A male redfin shiner will then defend the territory until a female comes along and spawning occurs, (Becker, George, 1983).

Redfin shiners live in streams and rivers with gravel and sand bottoms and some little vegetation. They are found in Mississippi River and the larger great lakes region. They are used by anglers as bait in catching sports fish such as crappie and bass and are also used in freshwater aquariums.


Of the Wisconsin 160 species of rare and endangered fish, some species are great concerns to myself and organizations around me.  One of the primary duties of the Bureau of Natural Heritage Conservation is to offer authorization, permits, and licenses for activities that involve the unique and the endangered species. DNR programs have also been put in place to try and restock the fishes in their natural habitat. In the effort to boost their population the authorities are met with challenges that are beyond their powers to change. These are mostly the environmental and the climate variation like the change in water temperatures, oxy-thermal habitat loss, silting and eutrophication. Other challenges like water pollution by use of chemicals from agricultural farms, the building of dams that block the fish breeding programs and overfishing are solely human-made.


~Michael Goetzman






Becker, George (1983) Fishes of Wisconsin retrieved from

Becker, George (1983) Fishes of Wisconsin: walleye retrieved from

Dave Bosanko (2007) fish of Wisconsin Field Guide (Fish Identification Guides)

George C. Becker (1983) Fishes of Wisconsin

Schmidt, J. (1922). “The breeding places of the eel.” Philosophical Transactions of the Royal Society of London, Series B

Slow Sprint (2010) Freshwater Fishing Know Before You Go

Wisconsin DNR (2007) Understanding Cisco Decline in Wisconsin’s Inland Lake…/TimParks_UnderstandingCiscoDeclineinWisconsin’sInlandL…

Wisconsin DNR (2007) Longear sunfish in Wisconsin retrieved from…