Lake Guntersville is a reservoir on the Tennessee River, northern Alabama. As Alabama’s largest reservoir, it hosts a wide variety of fish species, and recreational fishing is enormously important to the economy of local communities. The lake is home to vast expanses of aquatic vegetation, including native species such as eelgrass, white water lily, and water primrose.
These plant species have many positive effects on the ecology of the lake, such as enhancing water clarity, stabilizing the substrate, boosting biodiversity, and providing habitat for many different fish species. In fact, the great diversity of fish life in Lake Guntersville can be largely attributed to high aquatic plant abundance; studies have shown that the two correlate.
In addition to native plant species, Lake Guntersville hosts various invasive plant species such as Eurasian watermilfoil and hydrilla. The conditions of the lake are such that these aquatic plants thrive, and they have become a nuisance with serious effects on the ecology of the lake. Watermilfoil has the potential to interfere with fish spawning in the shallower regions of the lake, and sports activities may also be affected by the increase in invasive vegetation.
Bass
Bass are the predominant game fish in Lake Guntersville, with people traveling from afar to fish for them. Numerous species of bass are present in the lake, including four species of black bass. Fishing tournaments are frequently held at Lake Guntersville, with black bass (of the genus Micropterus) being highly sought after.
Hybridization commonly occurs between various black bass species found along the Tennessee River: these hybrid fish often demonstrate a poor ability to adapt to their environment and thus have reduced fitness compared to the species they were produced from.
1) Largemouth bass (Micropterus salmoides)
Largemouth bass have been reported to reach lengths of 97 cm (38.2 in). They are best suited to subtropical conditions with a muddy or sandy substrate and clear water. The diet of largemouth bass changes as the fish mature, with juveniles targeting crustaceans, insects, and small fish, while adults tackle larger fish species, crayfish, and frogs.
During spawning, these fish stop feeding altogether: the male builds a nest and guards it, while the female may visit several nests to spawn. As well as being a popular game fish, largemouth bass are also predated by herons, bitterns, and kingfishers. The species is also a victim of the largemouth bass virus, which has been shown to be most prevalent in juveniles and individuals ranging from 25 – 40 cm (9.8 – 15.7 in) in length. Fish are still safe to eat with the infection, but care must be taken to ensure that they are thoroughly cooked.
2) Smallmouth bass (Micropterus dolomieu)
In contrast to the largemouth bass, smallmouth bass prefer shallow areas with a rocky or gravel substrate. This species can attain lengths of around 70 cm (27.6 in). While juveniles feed on plankton and aquatic insect larvae, adults maintain a diet of crayfish and fish – including other smallmouth bass. The growth of cannibalistic fish has been shown to be improved from that of non-cannibalistic individuals and may also affect the competitive relationships between fish for resources.
3) Spotted bass (Micropterus punctulatus) and Guadalupe bass (Micropterus treculii)
The spotted bass and Guadalupe bass are the two other species of black bass found in Lake Guntersville. While the spotted bass prefers subtropical conditions, the Guadalupe bass is better suited to a temperate environment: this difference is reflected in the water depths they occupy within Lake Guntersville.
The spotted bass can reach lengths of 63.5 cm (25 in), whereas the Guadalupe bass is smaller with maximum lengths of around 45 cm (17.7 in). Both species prefer a gravelly substrate. Spotted bass juveniles feed on small crustaceans and midge larvae, whereas the adults’ diet consists of insects, larger crustaceans, frogs, worms, and small fish.
4) Striped bass (Morone saxatilis)
The striped bass is predominantly a marine species but is occasionally found inland in freshwater, hence its presence in Lake Guntersville. A large fish capable of reaching 200 cm (78.7 in) in length (although more commonly 120 cm (47.2 in)), the adults predate other fish and crustaceans. Juveniles feed on shrimp and small crustaceans, and the larvae subsist on a diet of zooplankton.
The striped bass stops feeding prior to spawning. Interestingly, they do not always spawn every year, although when they do, they may spawn more than once in a season. During spawning season, the striped bass journey up to the Guntersville Dam, which blocks their journey and creates a popular fishing spot.
5) White bass (Morone chrysops) and yellow bass (Morone mississippiensis)
White bass and yellow bass are closely related, however white bass prefer temperate waters and are usually found at depths greater than 14 m (46 ft), whereas yellow bass thrive in subtropical environments. Both species reach around 45 cm (17.7 in) and are important game fish.
Adults of both species feed on other fish, but the juveniles differ in their dietary preferences, with white bass young feeding on a variety of small invertebrates, while young yellow bass have a diet of mainly microcrustaceans and midge larvae.
Catfish
Five species of catfish are found in Lake Guntersville: the channel catfish (Ictalurus punctatus), the flathead catfish (Pylodictis olivaris), the blue catfish (Ictalurus furcatus), the yellow bullhead (Ameiurus natalis), and the black bullhead (Ameiurus melas).
The channel catfish is the predominant game fish; it can reach lengths of 130 cm (51.2 in) and can be cooked in a variety of ways. All three species are demersal and prefer subtropical conditions, with clean water and a sandy or gravelly substrate. The blue catfish prefers deep water, although will move up through the water column at night to feed on invertebrates, clams, and fish. Catfish are predominantly nocturnal species, and they have sensory barbels on their heads to aid this lifestyle.
The spawning habits of catfish are varied, with channel catfish laying eggs in a hole dug in the sand, while blue catfish lay their eggs in nests situated underneath debris. The male of each species builds these nests and then continues to guard the eggs after spawning.
The yellow and black bullhead differ from the other catfish species found in Lake Guntersville. Reaching around 65 cm (25.6 in), these two species prefer temperate waters with a soft substrate. The black bullhead feeds nocturnally, consuming clams, snails, plant material, and fish, while the yellow bullhead feeds on insects, mollusks, and crustaceans. Despite being edible, the black bullhead is considered to be a nuisance and is commonly caught by accident.
Sunfish
Six species of sunfish can be found in Lake Guntersville: the longear sunfish (Lepomis megalotis), redear sunfish (Lepomis microlophus), green sunfish (Lepomis cyanellus), redbreast sunfish (Lepomis auritus), bluegill (Lepomis macrochirus), and warmouth (Lepomis gulosus).
Their preferred conditions and regions they occupy within the lake vary, with longear and green sunfish occupying the benthopelagic region, while redear sunfish, redbreast sunfish, and warmouth are demersal. Longear sunfish, redbreast sunfish, and warmouth are temperate fish, whereas redear sunfish, green sunfish, and bluegill prefer subtropical conditions.
With the exception of the bluegill, which prefers deep weed beds, all species prefer vegetated, shallower water with mud, sand, or rocky substrate: this preference for vegetation means that Lake Guntersville is ideal with its plethora of aquatic plant life. The dietary niches of these four species vary, although there is some overlap, with aquatic insects, small fish, and microcrustaceans forming a large part of what the sunfish consume. However, the redear sunfish differs in that it feeds predominantly on mollusks, and this species has been suggested as a potential mode of control for snail vectors of schistosomiasis, a parasitic worm that has health implications for humans as well as other animals.
Carp
1) Common carp (Cyprinus carpio)
The common carp is a popular game fish, reaching lengths of 120 cm (47.2 in). While it is tolerant of a wide variety of conditions, it prefers vegetated areas, so is well-suited to life in Lake Guntersville. The larvae of common carp also prefer vegetated areas in shallow, warm water along lake margins. A crepuscular species, it occupies the benthopelagic region where it feeds on crustaceans and aquatic insects.
2) Grass carp (Ctenopharyngodon idella)
The grass carp is a subtropical game fish that can reach lengths of 150 cm (59.1 in). Similar to the common carp, it is adapted to live in vegetated areas, with a diet consisting mainly of aquatic plants and submerged grasses, although it will also predate on invertebrates. The grass carp is used in many areas for weed control, however, in other regions it is considered a pest due to the damage it can inflict on vegetation.
Lake Guntersville has been re-stocked with grass carp in the past, which resulted in the decline of many native species as well as invasive species. Research has suggested that the use of grass carp as a way to control aquatic plants creates an ‘all-or-nothing’ response, which may not be the most ecologically beneficial.
Shiners
There are four different species of shiner found in Lake Guntersville: the Texas shiner (Notropis amabilis), the blacktail shiner (Cyprinella venusta), the golden shiner (Notemigonus crysoleucas) and the red shiner (Cyprinella lutrensis). These are relatively small fish, with the Texas shiner and red shiner being very small: typically reaching just 6 and 9 centimeters (2.4 and 3.5 in) respectively.
All four species are suited to subtropical conditions and benthopelagic living, with just the golden shiner rising higher in the water column to feed on plankton, insects, and mollusks. Golden shiners are frequently used as bait and also to supplement the diets of largemouth bass, being well suited to this role due to their high adaptability and tolerance to varying conditions. The golden shiner can reach lengths of 30 cm (11.8 in) and preferentially inhabits vegetated areas, making Lake Guntersville the ideal place to reside!
Gar
Four species of gar can be found in Lake Guntersville, where they function as apex predators with long life spans. Alligator gar (Atractosteus spatula) are the largest, capable of attaining lengths of 300 cm (118.1 in)! Typically found in quieter areas of the lake, they feed on turtles, waterfowl, and small mammals, and are popular sport fish due to their impressive size. Gar can tolerate very low oxygen levels in the water due to their ability to breathe air atmospherically.
The three remaining species – the spotted gar (Lepisosteus oculatus), the shortnose gar (Lepisosteus platostomus), and the longnose gar (Lepisosteus osseus) are demersal, feeding on fish, crustaceans, and insects. The shortnose gar in particular prefers vegetated areas and submerged debris, where it lays its eggs. The eggs of the longnose gar, alligator gar, and spotted gar are highly poisonous due to the presence of ichthyotoxins.
Research has shown that gar populations are in decline due to habitat loss, pollution, and changes caused by the construction of dams. They are also heavily overfished, although there is the possibility of culturing them in captivity which may alleviate this pressure.
Buffalo
Lake Guntersville is home to smallmouth buffalo (Ictiobus bubalus), bigmouth buffalo (Ictiobus cyprinellus), and black buffalo (Ictiobus niger). These are large species capable of reaching lengths of 120 cm (47.2 in) and are popular game fish.
The smallmouth buffalo feeds on shellfish and algae, while the bigmouth buffalo consumes copepods and midge larvae. The black buffalo subsists on a diet of algae, diatoms, and crustaceans. These fish prefer to spawn over sand or gravel substrate, and one female may mate with several males during spawning.
Crappie
Black (Pomoxis nigromaculatus) and white (Pomoxis annularis) crappies can be found in Lake Guntersville. Both species can attain lengths of 50 cm (19.7 in) and are largely bottom dwelling, preferring muddy or sandy substrate in well-vegetated areas.
The diet of crappies varies with age: individual black crappies less than 16 cm (6.3 in) in length consume planktonic crustaceans, whereas larger individuals consume other small fish. Young white crappies feed on microcrustaceans and small insects while adults predate fish such as shad. The best place to find crappie is towards the lower end of Lake Guntersville, where the water is slower flowing and there are more trees in the vicinity.
Drum
Lake Guntersville is home to both freshwater drum (Aplodinotus grunniens) and red drum (Sciaenops ocellatus). These large game fish are unusual in that they produce sound throughout the reproductive season, which forms part of their courtship ritual. Studies have shown that these sounds are species-specific and also depend on the water temperature.
The red drum typically feeds on crustaceans, mollusks, and other fish, while the freshwater drum’s diet is age dependent. Adult freshwater drum consume a varied diet of aquatic insects, amphipods, fish, crayfish, and mollusks, while juveniles feed on zooplankton and larvae consume the larvae of other fish species.
Another fascinating fact about the freshwater drum is that the otoliths, or ear bones, are known as ‘lucky stones’ and are frequently found washed up on the beaches of lakes such as Lake Guntersville.
Sauger (Sander canadensis) and walleye (Sander vitreus)
These two species are closely related, so much so that they can hybridize during the overlap of their spawning periods: spawning occurs in small groups, thus facilitating hybridization. The sauger can reach lengths of 70 cm (27.6 in), while the walleye is larger with maximum lengths of 100 cm (39.4 in). They have a preference for clear water over sand or gravel, with plenty of vegetation.
Adult and juvenile sauger feed on fish, whereas walleye also consume insects. Walleye prefer yellow perch and freshwater drum, however if fish are hard to come by, they will expand their diet to include crayfish, frogs, and small mammals. Both species are nocturnal and thus possess a tapetum lucidum, a reflective layer in the eye that boosts the retina’s sensitivity to light.
Rainbow trout (Oncorhynchus mykiss)
Rainbow trout are tolerant of a wide range of ecological conditions, however, they thrive in highly oxygenated water and thus are well suited to Lake Guntersville, with its abundance of aquatic plant life. These are popular game fish that can reach lengths of 120 cm (47.2 in). Being part of the salmon family, these fish are known for their pink flesh, which is a result of the pigment astaxanthin. Farmed trout are commonly given canthaxanthin to further pigment their flesh.
Fathead minnow (Pimephales promelas)
The fathead minnow feeds on detritus and algae and is highly tolerant of varied conditions such as pH, alkalinity, and temperature. With a maximum length of 10 cm (3.9 in), it provides a valuable food source for larger fish species. During spawning, the male fathead minnow becomes incredibly territorial, fiercely defending his nest site.
Pimephales promelas provides an excellent model for aquatic toxicology research due to its tolerance to experimentation, and it can be compared with other species to estimate the effect of various toxins on a broad range of aquatic animals.
Threadfin shad (Dorosoma petenense) and gizzard shad (Dorosoma cepedianum)
Threadfin shad are quite small fish, typically reaching around 10 cm (3.9 in), although they have been recorded at lengths of 30 cm (11.8 in). Often seen in schools, they occupy both the pelagic and neritic zones and prefer to inhabit steep-sided surfaces such as dams. This species is a filter feeder but has also been found to consume copepods and fish fry. Their eggs are adhesive and stick to aquatic vegetation.
In contrast, the gizzard shad is capable of reaching larger sizes (over 50 cm (19.7 in)) and is better suited to open water, where it filter feeds on phytoplankton and zooplankton. The eggs of the gizzard shad are adhesive and sink to the lake bottom, where they hatch in the muddy substrate.
One feature that allows the threadfin and gizzard shad to be distinguished from each other is the lower jaw: in the gizzard shad, the upper jaw typically protrudes beyond the lower jaw, whereas in the threadfin shad this is not the case.
Chain pickerel (Esox niger)
The chain pickerel is a member of the pike family and can reach lengths of almost 100 cm (39.4 in). This species suits the highly vegetated habitat offered by Lake Guntersville, but can also be found in deeper, colder waters with much less plant life, especially during the winter. Chain pickerel are an elusive species, with juveniles burying themselves in the mud and larvae hiding among vegetation. Adults feed on other fish species, such as shad.
American eel (Anguilla rostrata)
The American eel occupies areas with a muddy or silty substrate, where it feeds on insect larvae, gastropods, and fish. A nocturnal feeder, during the day it shelters under banks or submerged objects.
This species has a fascinating life cycle, with the larvae being shaped like a willow leaf before metamorphosing into elvers. American eels are fished commercially, usually caught using eel pots or trot lines; unfortunately, heavy fishing and loss of habitat have led to the decline of this species.
Paddlefish (Polyodon spathula)
Paddlefish are highly distinctive, with a long rostrum protruding from their snout. This is equipped with an electrosensitive function that enables the paddlefish to locate and feed on plankton. Studies have suggested that the sensitivity of the paddlefish’s rostrum to metals may impact their movement through dams.
The paddlefish is capable of reaching 220 cm (86.6 in) and is found in water deeper than 1.2 m (3.9 ft). Overfishing, habitat loss, and pollution have caused the decline of this species, which is now classified as vulnerable.
Bowfin (Amia calva)
As with many of the species found in Lake Guntersville, the bowfin prefers areas with abundant aquatic vegetation, where it feeds on other sport fish, frogs, crayfish, insects, and shrimp. The bowfin is a living fossil, possessing many primitive features. It is tolerant of high temperatures, and in stagnant water can breathe atmospheric air at the water’s surface.
The eggs of the bowfin are adhesive and are laid in a nest guarded by the male. Following hatching, the male continues to follow the young around, protecting them from predation.
Rio Grande cichlid (Herichthys cyanoguttatus)
The Rio Grande cichlid typically occupies warm waters with plenty of vegetation, where it consumes worms, crustaceans, and plant matter. In this species, both parents care for the young. Herichthys cyanoguttatus is not native to Lake Guntersville, and studies have shown that it can be aggressive to species such as bluegill and redear sunfish.
