Sauger
The sauger (Sander canadensis) is a freshwater perciform fish of the family Percidae which resembles its close relative the walleye. They are members of the largest vertebrate order, Perciformes.[2] They are the most migratory percid species in North America.[3] Saugers obtain two dorsal fins, the first is spiny and the posterior dorsal fin is a soft-rayed fin. Their paired fins are in the thoracic position and their caudal fin is truncated which means squared off at the corners, a characteristic of the family Percidae. Another physical characteristic of Saugers are their ctenoid scales which is common in advanced fishes. Saugers have a fusiform body structure, and as a result saugers are well adapted predatory fishes and are capable of swimming into fast currents with minimal drag on their bodies. They may be distinguished from walleyes by the distinctly spotted dorsal fin, by the lack of a white splotch on the caudal fin, by the rough skin over their gill, and by their generally more brassy color, or darker (almost black) color in some regions. The average sauger in an angler's creel is 300 to 400 g (11 to 14 oz) in weight.
Saugers are a widely distributed fish species. Their historical range consisted of eastern U.S west of the Appalachian Mountains, mostly southern, central, and western U.S up into southern Canada.[2] Sauger distribution and range has decreased from historical ranges because of degraded and fragmented habitat conditions.[4] Sauger distribution within its home range varies by time of year because they are a migratory fish species.[4] Saugers are more typical of rivers whereas walleyes are more common in lakes and reservoirs. In many parts of their range, saugers are sympatric with walleyes. Hybridization between saugers and walleyes is not unknown; the hybrids, referred to as saugeyes, exhibit traits of both species. Being intermediate in appearance between the two species, saugeyes are sometimes difficult to differentiate, but they generally carry the dark blotches characteristic of the sauger. Saugers, however, are usually smaller and will better tolerate waters of higher turbidity than the walleye. Saugers require warmer summer water temperatures of 20-28 degrees Celsius. The need for warm water temperatures is thought to affect the northern and western boundaries of their range.
Sauger are most likely to be found in large rivers with deep pools with depths greater than 0.6 m. Pools with depths less than 0.6 m are not likely to yield saugers.[5] They encounter a variety of habitats because of their migratory tendencies. They are usually found in natural rivers because they have more abundant pools and their flow regime has not been altered by dams or diversions. They are still common in impounded river systems. Diversions and dams affect habitat and spawning areas of Saugers. Saugers are usually found in areas with high turbidity, low channel slope, low stream velocity, and deep water.[3] Saugers tend to select pools with sand and silt substrates, and habitat features that provide cover from the river current.[5] They tend to avoid runs and riffles. They are most commonly found in pools that are at least 1.5 m deep. They can also be found in shallower pools but in lesser numbers. There have been no observed differences in habitat preference for males and females.[3] The amount of saugers observed will increase with mean summer water temperature, maximum water depth, and mean summer alkalinity.