Lake of the Woods is a shallow freshwater lake situated on the border between Minnesota, USA, and the Canadian provinces Ontario and Manitoba. First in line after the Great Lakes, it is the 6th largest freshwater lake located (though partially) in the United States. Lake of the Woods lies in the basin of what was once the world’s largest lake: Lake Agassiz. It is fed by the Rainy River and covers an area of 1,727 square miles (4,472 km2). It is speckled with 14,522 islands and is famous for its beautiful scenery, wilderness, and wildlife.
Lake of the Woods is a complex waterbody, composed of several distinct basins with different water characteristics. The southern basin is shallow and relatively uniform with a well-mixed water column. The northern basin is deeper and more heterogeneous with several bays and thousands of islands. During the early 19th century, the lake was fed industrial waste and domestic sewage waters by its river inlet. However, due to drastically improved wastewater treatment, the water is now of high quality and sustains a diverse community of fish, the most interesting of which can be found in the list below.
Fish Species in Lake of the Woods
1) Atlantic salmon (Salmo salar)
The Atlantic Salmon is a member of the Salmonidae family (salmon). In their native habitat, they are anadromous, meaning they spend a part of their life in freshwater (where they spawn and hatch) and a part of their life in the ocean. Landlocked populations, such as the one in Lake of the Woods, move between the lake and the surrounding streams, which is known as a potamodromous life cycle. The individual Atlantic salmon is known to display high fidelity to its native stream, returning to spawn after one to three years at sea. The vast majority die shortly after spawning, but a few individuals might spawn 2 – 3 times in their life.
The females prepare a depression in the river bottom known as a redd, where she lays her eggs. They are immediately fertilized by a waiting male, after which the female covers the eggs with gravel. The time it takes for the eggs to hatch depends on the water temperature. The young fish, known as smolt, usually leave the river during the late spring. The age of an Atlantic salmon can be determined by looking closely at their scales. When they just emerge from the gravel, they have no scales. Small calcareous plates will then start to develop, building concentric rings which vary in spacing in relation to feeding activity. A dark band on the scales known as an ‘annulus’ marks the end of winter and can be used to count the years a salmon has lived.
2) Black crappie (Pomoxis nigromaculatus)
The black crappie is a freshwater fish in the Centrarchidae family (sunfish) belonging to the Pomoxis genus, together with the white crappie. The black crappie can be recognized from its white sister species by irregular dark blotches that cover the whole body and a higher number of dorsal spines. They are opportunistic feeders known to be active primarily at night. They feed on crustaceans, aquatic larvae, and small fish. The crappie season at Lake of the Woods is open throughout the year with a possession limit of 10.
The black crappie spawns in late spring or early summer depending on the water temperature. As the fry develop, they undergo sexual differentiation of the gonads, meaning the sex is not determined when they hatch. Prior to the sexual differentiation, black crappie fry are sensitive to androgens, such as testosterone. Androgens are a group of sex hormones integral to sexual and reproductive development. They are produced by both males and females, but males make more. If exposed to high levels of these, a process known as masculinization can take place, resulting in most of the population being male, and some individuals even developing as intersex. This is actively used in aquaculture, where the males are known to grow faster.
3) Brown bullhead (Ameiurus nebulosus)
The brown bullhead is a freshwater catfish with a dark brown to olive-green dorsal side. The sides and the belly are lighter in color and are strongly mottled, compared to other bullheads. This provides them with good camouflage amid submerged vegetation or near logs. The barbels spring from around the mouth, with larger barbels protruding at the corner of the mouth. These barbels give the brown bullhead an acute sense of smell.
Brown bullheads prefer clear, sluggish waters and soft substrates and are very resistant to low oxygen concentrations. They can tolerate high temperatures and pollution, and they will bury themselves in mud when their surrounding conditions become too adverse, like in the cold winter months. The brown bullhead, like other catfishes, mainly feeds at night, when they use their barbels to locate feed. They prey on mollusks, crayfish, worms, eggs, and small fish, but can also feed on plant material and algae.
4) Burbot (Lota lota)
The burbot is the only freshwater Gadiform (cod & its allies), which is how it got the nickname “freshwater cod”. It has one central barbel on the chin and can be distinguished from other species by its very long second dorsal fin (at least 6 times as long as the first). They are found in well-oxygenated flowing waters and find shelter among submerged vegetation or in crevices. They are sensitive to water temperatures and move to deep waters in summer, where movement from the deeper pockets only occurs when feeding during the night.
Populations of burbot differ in their life history. Some stay in the lake or river they hatch in, while others migrate between. This is known as adfluvial, which means they spawn in tributary streams, where the juveniles stay for multiple seasons, before migrating back to the lake to grow to maturity. The burbot lives circumpolar, but there is great debate regarding the identity of the North American burbot, which some ichthyologists pool with the European burbot, while others believe the species is a subspecies of Lota lota and should have its own species name (Lota maculosa).
5) Channel catfish (Ictalurus punctatus)
The channel catfish is a popular sports fish in the Ictaluridae family (catfish). The whole family is native to North America and includes 51 species. The species is stocked each year in Lake of the Woods by the State Hatchery System. The popularity of the fish has prompted a spread of the species in domestic stock like aquaculture. A recent study set out to investigate the genetic diversity (how different each fish is from the next) in various populations to provide instructive information for future broodstock selection and management. This study revealed that the average fish from the farm populations was fairly similar, consistent with the historical origin and management of the fish.
The channel catfish typically spawns between April and July, when water temperatures reach 75 °F (24 °C). In preparation, the male and female dig a depression in the substrate. The males turn dark during the spawning season, and they develop a thick pad on top of their heads. When the eggs have been fertilized, the males guard the nest. They hatch in about a week, after which the fry remain guarded by the male for another week.
6) Cisco/Tullibee (Coregonus artedi)
The cisco or tullibee is a species in the Salmonidae family (salmon) and is also known in North America as the lake herring. The species is so like the Arctic cisco (Coregonus autumnalis) that it is hard to distinguish them even on a genetic level. Research suggests that a network of freshwater lakes in the late Pleistocene allowed the fish to migrate from Siberia across the Bering land bridge and that the modern lake cisco (C. artedi) is derived from the Arctic variant.
The cisco is a pelagic fish, living neither near the bottom nor surface of the lake, where they feed on zooplankton and insect larvae. They are also known to consume fish eggs, even those of their own species. The cisco are not themselves a large fish species, typically weighing from six ounces to two pounds (200 grams to a kilo). Therefore, they are an important food source for larger lake species such as the lake trout, northern pike, burbot, yellow perch, and walleye.
7) Golden redhorse (Moxostoma erythrurum)
The golden redhorse is a smaller-bodied species in the Catostomidae family (suckers). They are covered in large scales, ranging from a golden dorsal side to a cream-colored belly. The dorsal fin is short and the lower fins can be a striking orange. They use their fleshy lips to feed on the bottom of the lake, consuming various invertebrates such as larval midges and mayflies. This effectively influences how many of these insects grow to become the flying adults we are familiar with.
The golden redhorse is endemic to Ontario and the eastern freshwater lakes and rivers of the United States. It is similar in looks to the black redhorse and silver redhorse, but it is the smallest of the three. They are not often found in lakes but prefer pools or rivers with rocky or muddy bottoms.
8) Lake sturgeon (Acipenser fulvescens)
The lake sturgeon, also known as the rock sturgeon, is a freshwater fish in the Acipenseridae family (sturgeon). It was under intense commercial harvest during the late 1800s and early 1900s and the population declined to a point where commercial fishing almost completely stopped. Due to pollution from the Rainy River, the species was unable to rebound for many decades. Today, reproduction is successful in most years, and the lake sturgeon can more often be found at the mouth of the Rainy River. The fishing season opens from July 1 to Sept 30, and only one sturgeon is allowed per angler per year, which must be between 45 and 50 inches (114.3 to 127 centimeters).
The lake sturgeon migrates to spawn in early summer. They rarely migrate more than 250 miles upriver and stop feeding for the migratory period. The males arrive first at the site and wait for the females. They primarily spawn in areas with turbulent water, e.g. at the foot of a low fall. Without access to suitable spawning habitats, they can be observed to spawn around rocky islands. The eggs adhere to rocks and logs and hatch in 5 – 8 days depending on water temperature. The number of eggs a female lays greatly depends on her size, and the females tend to be much larger than the males.
9) Lake trout (Salvelinus namaycush)
The lake trout is a freshwater fish in the Salmonidae family (salmon). They have a dark dorsal side, which gets gradually lighter towards the belly of the fish. They are covered with light spots, which distinguishes them as belonging to the chars. The lower fins are orange with a white edge, and the tail fin is deeply forked. The lake trout is a slowly maturing species. They generally become sexually mature around 6 – 7 years of age and can live for more than 25 years.
The lake trout is a popular sports fish and is common in parts of Lake of the Woods like Whitefish Bay and Clearwater Bay, which have deeper waters. They can be found in shallower parts of the lake when the water is colder, as they prefer the water to be between 40 and 55 °F (4.5 – 13 °C). The fishing season is open from May 14 – Sept 30 and the possession limit is 2 trout, however there is always the option of catch and release.
10) Lake whitefish (Coregonus clupeaformis)
The lake whitefish is a member of the Salmonidae family (salmon), belonging to the Coregonus genus, which is commonly known as whitefishes. They can be hard to distinguish from the cisco, a pelagic member of the same genus. The lake whitefish is a benthic feeder, which is revealed by the snout that hangs over the lower jaw, which on the cisco extends up to or past the tip of the snout. The lake whitefish also grows to a larger size than the cisco.
The lake whitefish inhabits large lakes and rivers. They follow quite distinct movement patterns, moving from deep to shallow water in the spring, then back as the water temperature rises. They feed mainly on aquatic insect larvae and mollusks. They migrate to shallow water in fall to early winter to spawn, then they go back to deep water after spawning. The lake whitefish spawn at night. In a move towards the surface, the female releases her eggs, followed by males releasing milt to fertilize them. The spawning fish can sometimes be seen leaping out of the water.
11) Largemouth bass (Micropterus salmoides)
The largemouth bass is a member of the Centrarchidae family (sunfish) with a light green body and a dark lateral line. They have two distinct dorsal fins. The first has thick spiny rays, while the second has soft rays. The upper jaw extends beyond the rear of the eye. They are carnivorous and prefer to feed on smaller fish like minnows, but they will also feed on crayfish, amphibians, and insects.
Largemouth bass prefer quiet, clear water and can usually be found over mud or sand. The fishing is open year-round at Lake of the Woods, and together with smallmouth bass, there’s a possession limit of 6. Nearing the spawning season in spring or early summer, the males build nests in the shallow water, which they protect with territorial and aggressive displays. The females may spawn with several males in different nests. During the spawning periods, the adults stop feeding. After spawning, the males guard and fan the eggs for up to a month.
12) Muskellunge (Esox masquinongy)
The muskellunge is a large carnivorous freshwater fish in the Esocidae family (pike). It is a popular sports fish with a long list of nicknames, but it is mainly known as the muskie. The fishing season at Lake of the Woods opens on June 18 and lasts until Nov 30. You can catch one fish over 50” (1.27 meters) and they are not uncommon to find in this lake! With their great size, the muskie is often the apex predator. They hunt anything from smaller fish to ducklings, muskrats, and even snakes.
The muskie becomes mature at an age of 3 – 5 years and spawns in May, slightly later than the northern pike, when the water temperature is between 48 – 59 °F (9 – 15 °C). The slight delay is known as a temporal barrier and helps prevent the two species from hybridizing. This still happens occasionally, resulting in the tiger muskie, a fast-growing but usually sterile hybrid species. The female muskie lays her eggs in depressions covered by submerged vegetation. A single female can lay between 60,000 and 100,000 eggs depending on her age.
13) Northern pike (Esox lucius)
The northern pike is another member of the Esocidae family (pike) roaming the waters of Lake of the Woods. Like the muskie, the northern pike is a solitary hunter and can be highly territorial. They have a long snout, a large mouth, and prefer clear vegetated lakes. The adults feed mainly on smaller fish, but they will also hunt crayfish and frogs. The young feed mainly on invertebrates. In addition, they are cannibalistic in almost all life stages.
The northern pike is a common catch at Lake of the Woods and can be caught there year-round. In summer they typically search out deeper waters, but they move to the shallows to feed. When the water temperature drops, they will stay more permanently in shallow waters. The possession limit is 3, but of these only one can be larger than 40 inches (101.6 centimeters). Keep in mind that all fish in the 30” – 40” (76 – 102 centimeters) range must be released immediately.
14) Rainbow trout (Oncorhynchus mykiss)
The rainbow trout is a member of the Salmonid family (salmon), recognizable by its characteristic red band running along the body from the eye to the tail. The dorsal side is olive-green, while the belly is milky white, however their coloration can vary with habitat and size. They eat a variety of aquatic and terrestrial invertebrates and small fishes. Since they are a popular sport and eating fish, they are stocked in almost all water bodies.
The rainbow trout is native to the Cascade Range, but they have recently (2017) been stocked in river systems close to Lake of the Woods. They become sexually mature at 2 – 3 years old and can, in contrast to other salmon species, spawn over successive seasons, which means they can reach ages of up to 11 years old. They migrate from cool lakes to rivers and tributaries or stay close to the inlet or outlet of lakes when it becomes time to spawn. They are the same species as the steelhead trout; however, this ‘variant’ is anadromous, which means that it migrates to the sea as an adult.
15) Sauger (Sander canadensis)
The sauger is a freshwater fish in the Percidae (perch) family and can reportedly live to the age of 18. They inhabit sand and gravel runs or in sandy and muddy pools. They spawn between March and June. The sauger is not as frequently found in lakes, but when present they spawn over sandy or rocky shores, or they leave the lake to spawn upriver. The species is not uncommon, but they live in many subpopulations and locations. The populations are generally considered to be relatively large and stable, or potentially slowly declining.
The sauger can be caught in Lake of the Woods throughout the year. Because of the similarity to the walleye, there’s a 6 fish possession limit, of which a maximum of 4 can be walleye. The two species can be distinguished by visual inspection. The sauger is typically smaller than the walleye, with dark blotches on a golden body and dark spots on the dorsal fins. The tail fin of the walleye has a white lower tip.
16) Smallmouth bass (Micropterus dolomieu)
The smallmouth bass is native to the eastern United States and southern Canada and belongs to the Centrarchidae (sunfish) family. They have been introduced across most of North America and are even considered an invasive species in Ontario, where introductions were allowed until the late 1900s. They prefer large clear lakes and seek shelter in deep waters or pools when the water temperature rises. They come to shallow waters or quiet areas of streams in the spawning season, where males prepare nests for the females to lay their eggs in.
The recent spread of smallmouth bass is considered a result of accidental introductions after using the fish as live bait. They are effective top predators feeding on anything from insects, crayfish, and fish, to plant material. Because of their opportunistic feeding habits, they are regarded as a high risk to native biota, especially in small lakes. Once they have arrived in a water body the probability of establishment is very high.
The smallmouth bass can be caught at Lake of the Woods, where the fishing season is open year-round. Together with largemouth bass, there is a possession limit of 6 fish.
17) Walleye (Sander vitreus)
The walleye is a freshwater fish in the Percidae (perch) family. The name stems from the reflective layer of pigment, known as tapetum ludicum, in their eyes, which helps them feed in low light & at night and gives the eyes a pearlescent look. The Latin species name ‘vitreus’, meaning glassy, is also a nod to their silvery eyes.
The walleye and sauger are closely related and can hybridize, which gives rise to the saugeye. The hybrid species typically grows faster and survives better in turbid waters and has therefore become popular to stock. However, while the two species can naturally hybridize when their ranges overlap, it is much more common when saugeye is stocked, as it is in Lake of the Woods. This increases the risk of genetic contamination of the parent species.
The walleye is very abundant in Lake of the Woods. It is a popular sports fish that you can catch year-round. The possession limit is 4, however all Walleye in the 19.5” – 28” range must be immediately released (49.5 – 71 cm) and there’s a collective possession limit with sauger of 6 fish.
18) White sucker (Catostomus commersonii)
The white sucker is a member of the Catostomidae family (suckers), which use their fleshy lips to feed on benthic algae, other plant material, and benthic invertebrates. They are widely distributed across North America and are often abundant. Due to their frequent occurrence and feeding habits, they are regarded as a bioindicator. By tracking patterns in the population characteristics of white suckers, management groups can follow alterations in food availability and habitat quality. For example, if the populations start to shrink, it could be a sign of adverse chemical effects requiring active management to avoid detrimental toxicant effects on the lakes’ fish population.
The white sucker is adapted to a wide range of habitats, from rocky pools to large lakes. They typically come to shallower water around dawn and dusk to feed, but they can be found at depths greater than 45 meters. They are considered a migrator species since they often move great distances to spawn. During spawning, up to four males crowd a female and press their fins against her sides to prompt her to release her eggs. The eggs are sticky and adhere to gravel or other bottom substrates.
19) Yellow perch (Perca flavescens)
The yellow perch is a member of the Percidae family (perch), a family of ray-finned fish characterized by having two dorsal fins, the first containing spines, and the second soft rays. They have a deep olive-green to golden color and sport 5 – 8 dark vertical bands. The yellow perch can usually be found in clear weedy backwaters or shallow waters of lakes with heavy aquatic vegetation. However, they can also be seen in shoals near the shore in spring. They feed during the day on invertebrates, fishes, and fish eggs.
The yellow perch are, like the majority of bony fish (90%), oviparous, which means that the eggs are fertilized outside the female’s body. They spawn in late winter or spring. The female lay her eggs in neat ribbons along submerged vegetation while being trailed by groups of males that fertilize the eggs. The incubation time is dependent on water temperature, but averages around 12 days. The juveniles are popular feed for many other species, so to counteract the low survival rates, the yellow perch lay a high number of eggs.
The yellow perch at Lake of the Woods are famous for their size, averaging 10 – 12 inches (25 – 30 centimeters) and larger individuals are not uncommon. The daily catch limit is 20 per day or 40 in possession.
