Saugers possess a distinct appearance, resembling walleyes with a few notable differences. These fish exhibit a fusiform body structure, making them well-adapted predatory swimmers capable of maneuvering through fast currents with minimal drag. One distinguishing feature is their ctenoid scales, commonly found in advanced fishes. Saugers also have two dorsal fins, with the first being spiny and the posterior dorsal fin being soft-rayed. Their thoracic-positioned paired fins and truncated caudal fin further emphasize their affiliation with the Percidae family.
To differentiate saugers from walleyes, several characteristics come into play. Saugers exhibit a distinctly spotted dorsal fin, lack the white splotch on the caudal fin, have rougher skin over their gills, and display a generally more brassy or darker coloration, especially in certain regions. On average, a sauger weighs around 300 to 400 g (11 to 14 oz).
Historically, saugers occupied a vast range encompassing the eastern U.S. west of the Appalachian Mountains, southern and central regions of the United States, and extending north into southern Canada. However, due to habitat degradation and fragmentation, their distribution has undergone significant reductions. Saugers are more commonly found in rivers, while walleyes tend to inhabit lakes and reservoirs. These two species often share overlapping ranges, resulting in instances of hybridization. The hybrids, known as saugeyes, possess traits from both parent species, with characteristic dark blotches similar to those of saugers. Saugers, however, are generally smaller and better adapted to turbid waters than walleyes. The northern and western boundaries of the sauger's range are influenced by their preference for warmer summer water temperatures ranging from 20 to 28 °C (68 to 82 °F).
Saugers undertake remarkable migratory journeys during their reproductive cycle. They typically move upstream to spawn between March and May, varying based on their location. After spawning, which primarily occurs in rocky substrate pools, saugers embark on downstream migrations to return to their home locations from April to July. These migrations can span distances of 10 to 600 km, highlighting the remarkable nature of their reproductive behavior.
Females exhibit preferences for specific habitats during spawning, with rocky substrate pools being their preferred choice for depositing eggs. As females increase in size, both egg quality and fecundity improve, although egg production is believed to decline after reaching six years of age. Sexual maturity in saugers is generally reached between the ages of 2 and 5 years, with size serving as another indicator of maturity. A sauger is considered an adult once it reaches a length of 250 to 300 millimeters (9.8 to 11.8 in). Upon hatching, larval saugers drift downstream until they develop feeding tendencies and horizontal maneuverability. Juvenile saugers typically spend the autumn months developing in diversion canals and backwaters before migrating upstream to their winter habitat. Unfortunately, residing in diversion canals exposes juvenile saugers to increased mortality rates.
Saugers exhibit a diverse diet that varies based on the time of year and the fish's size. During spring, midsize and large saugers primarily feed on channel catfish (Ictalurus punctatus) and freshwater drum (Aplodinotus grunniens). Smaller saugers, on the other hand, mainly consume benthic invertebrates, mayfly larvae, and catfish. Throughout summer, the diet of midsize and large saugers shifts predominantly to mayfly larvae. However, during autumn, freshwater drum and gizzard shad (Dorosoma cepedianum) become the predominant food sources for saugers of all sizes. Fish make up over 99% of a sauger's diet during autumn. While saugers do prey on shiners during spring and summer, they do not account for a significant portion of their overall diet. The absence of shiners in their autumn diet is likely due to availability factors.
Saugers exhibit a preference for large rivers with deep pools, generally exceeding 0.6 meters in depth. Their migratory tendencies expose them to a variety of habitats. Natural rivers, with their abundant pools and unaltered flows, serve as prime sauger habitats. However, saugers can still be found in impounded river systems, although such systems often pose challenges due to diversions and dams that alter habitat conditions and hinder spawning. Saugers tend to select pools with sand and silt substrates, seeking out habitat features that provide cover from the river current. They typically avoid runs and riffles, favoring pools with a minimum depth of 1.5 meters. While no significant differences in habitat preference between males and females have been observed, the number of saugers observed tends to increase with mean summer water temperature, maximum water depth, and alkalinity.
The sauger and walleye belong to the North American clade within the genus Sander. It is estimated that the sauger speciated into its modern form approximately 7.3 million years ago, making it an ancient species with a rich evolutionary history. The sauger was formally described as Lucioperca canadensis in 1834 by British naturalists Edward Griffith and Charles Hamilton Smith, based on the work of French naturalist Georges Cuvier, which Griffith translated from French.
Saugers face numerous conservation challenges resulting from migratory barriers, habitat loss, entrainment in irrigation canals, and overexploitation. Dams and diversions hinder upstream spawning migration, altering crucial environmental factors such as turbidity, pool formation, and water temperature that significantly impact the timing and success of sauger spawning. Their long migratory journeys make them particularly vulnerable to the effects of dammed or diverted river systems. In periods of drought, low water levels pose a significant threat to sauger populations by stranding eggs during spawning and preventing larval saugers from reaching downstream locations. Additionally, exploitation by fishermen contributes to mortality rates, especially during the autumn season.
The sauger population in New York is critically imperiled, with only a small population remaining in Lake Champlain. In Lake Erie and Lake Ontario, saugers have been extirpated following a population crash in the 1950s. The construction of the Kinzua Dam in the Allegheny River has prevented saugers from reaching New York, prompting the initiation of a sauger stocking program in the upper Allegheny River. As of 2022, fishing for saugers in New York is prohibited statewide.