Thesis (M.S.)--Montana State University, 2004. / Title from PDF title page (viewed Jan. 6, 2005). Includes bibliographical references (p. 57-67).

Sauger Sander canadensis is a native, migratory sportfish found in large rivers and riverine impoundments, primarily in the central United States. The migratory nature of this species requires access to un-impounded sections of river in order to complete reproduction and other aspects of life history. This requirement, along with their popularity as a gamefish, has resulted in widespread declines in sauger populations throughout their range due to habitat alteration and fragmentation combined with harvest pressure. The lower Ohio River supports a sauger population that is impeded by multiple high head dams and is heavily exploited by recreational anglers. However, despite high popularity among anglers, relatively little is known about large-scale movement patterns of sauger in the lower Ohio River. Additionally, the contribution that tributaries make to the population in terms of both recruitment and use by adults has not been assessed. I identified analysis of trace elements and stable isotopes in otoliths as techniques that could help quantify the role that tributary habitats play in the Ohio River sauger fishery. First, I collected water from the Ohio River and its larger tributaries in order to test the null hypothesis that there were no persistent differences in Sr:Ca, δ18O, and Ba:Ca among rivers. Water and otolith Sr:Ca, δ18O, and Ba:Ca from Sander spp. were then compared to test the null hypothesis that there is no significant relationship between Sr:Ca, δ18O, and Ba:Ca in the water and Sr:Ca, δ18O, and Ba:Ca measured in the otolith. I applied this relationship to Sr:Ca, δ18O, and Ba:Ca measured in the core of sauger otoliths collected in four navigational pools to test the null hypothesis that there were no differences in sauger recruitment sources among the four pools sampled on the lower Ohio River. Finally, I analyzed changes in Sr:Ca, δ18O, and Ba:Ca across otolith transects of the same fish to identify movements between the Ohio River and tributary habitats and test the null hypothesis that there were no differences in movement probability by age or assigned origin. Analysis of water chemistry indicated significant differences in Sr:Ca between the Ohio River and its tributaries, but not among tributaries. There were no significant differences in either water Ba:Ca or δ18O between the Ohio River and its tributaries. Comparison of water and otolith chemistry of known origin individuals yielded significant relationships for Sr:Ca and δ18O, but not Ba:Ca. As a result, only Sr:Ca was used for origin and movement assessments. Analysis of otolith core Sr:Ca indicated that tributaries are an important source of recruitment for the lower Ohio River sauger fishery. Otolith Sr:Ca consistent with reaches upriver of the study area were also prevalent in otolith core samples, indicating upriver sources are important for maintaining population density in the study area. Movement analysis indicated high probabilities of movement to upriver habitats in all pools, along with high movement probability to tributary habitats among fish collected in all pools. The data indicated that adult sauger in the lower Ohio river were recruited from multiple sources, and there is a high degree of exchange between the Ohio River and its tributaries. High recruitment and movement probability from upriver areas of the Ohio River indicated that the study area I identified does not encompass all of the river used by the population(s) sampled. Managers should focus on unification of regulations and sampling protocol to reflect this expansive range.

Predation by saugers was evaluated from stomach contents of 550 saugers collected by gillnetting in the Gallipolis Pool of the Ohio River during June 1980 - August 1981. Abundance of prey items in the river was assessed from seine samples collected at similar sites during the same period. Gizzard shad were the most abundant prey in sauger stomachs, comprising 42% of all identified prey, followed by emerald shiners (28%), freshwater drum (16%), channel catfish (12%), and mimic shiners (1%). Close correlation between abundance and size of prey in stomachs and in seine samples suggested lack of selection by saugers. Annual food consumption of saugers averaged 1.1% of the body weight per day. Growth and daily ration were high from August to January (maximum in October) and low from March to July. Rapid growth and high food consumption throughout the fall and early winter relate to the extended period of high temperatures and increased availability of gizzard shad. Conversion efficiency estimates during the growing season averaged 20%, similar to reports for other aquatic systems. Annual conversion efficiency averaged 15.7%, indicating a 27% overestimate of annual efficiency levels through the use of only growing season data. Daily feeding activity was continuous for saugers during October - January when light intensity was low and food abundance and daily ration were high. Feeding was also continuous during March - May but was highly variable. Feeding was significantly greater during the daylight hours in June, but was reduced during daylight hours in August. Turbidity levels were much higher in June than in August and may have affected the patterns of feeding periodicity during these months. / Master of Science

Thesis (M.S.)--Tennessee Technological University, 2009. / Title from title page screen (viewed on Jan. 22, 2010). Includes bibliographical references.

This study has presented a comprehensive overview of the status and ecology of walleye and sauger in the Wabash River, Indiana. Populations of walleye and sauger are relatively low in numbers. Both species exhibited a trend of increased abundance with river km from the mouth of the Wabash River. Summer walleye habitat use and movements were examined in the upper Wabash River. Walleye preferred run habitat over riffle or pool habitat. Lateral position, substrate use, and mean depth appeared to be influenced by discharge. Movements were generally short and occurred within a relatively small home range of 1.7 km. The population size limits the fisheries potential for walleye and sauger in the Wabash River mainstem. The upper Wabash River supports higher abundances of these species than the middle Wabash River and may provide a focal point for future management efforts. / Department of Biology

Sauger Sander canadensis are a native top level predator and popular sport fish. They are native to large, turbid midwestern rivers and are a highly migratory species that relies on unrestricted access to specific habitats throughout their lifespan. Due to specific habitat requirements and popularity as a sport fish, Sauger are in decline across much of their range. Habitat alterations including barriers, channelization and sedimentation, as well as overharvest, have resulted in population declines. Sauger are often subject to relatively high levels of exploitation because of their tendency to concentrate below dams during migrations, which leaves them vulnerable to anglers. The lower Kaskaskia River below Carlyle Lake dam and the lower Ohio River contain important Sauger sport fisheries despite the presence of multiple dams on both rivers and the potential for high levels of exploitation. However, effects of current and potential harvest regulations on Sauger stocks in the Kaskaskia and Ohio rivers have not been assessed. From previous annual monitoring surveys, Sauger in the Ohio and Kaskaskia rivers have very different size and age structures and are managed under different regulations. Additionally, the Kaskaskia River and its largest reservoir (Carlyle Lake) are stocked annually with Sauger, but the contributions of stocked Sauger and immigrants from the Mississippi River to the Kaskaskia River Sauger stock are unknown. I first sought to assess population demographics of Sauger in the Kaskaskia and Ohio Rivers to gain a baseline understanding of both populations and then used these data to evaluate harvest regulations on each river. This objective tested the null hypothesis that no differences in recruitment indices, growth rates and mortality rates exist between Sauger populations within each river. Sauger in the Kaskaskia River are currently managed under a 356-mm minimum length limit and a 6-fish daily bag limit. Prior to 2018, the lower Ohio River was managed under no minimum length limit and a 10-fish daily bag limit. To assess the contribution of Sauger from different environments to the Kaskaskia River stock, I used otolith microchemistry to infer recruitment sources of fish and assess movement of fish between the Kaskaskia and middle Mississippi rivers. This objective tested the null hypothesis that no difference existed in the contribution of different rivers to the Kaskaskia River sauger population. The Ohio River Sauger population had a small age and size structure relative to the Kaskaskia River. Sauger from each river exhibited fast growth rates and high annual mortality. Population modeling indicated that the current 356-mm minimum size limit for Sauger in the Kaskaskia River is sufficient at preventing growth overfishing and is likely resulting in the larger size structure compared to the Ohio River. Sauger were likely experiencing growth and recruitment overfishing in the Ohio River under no minimum length limit and will likely benefit from the 356-mm minimum length limit implemented in 2018. Otolith microchemistry revealed that Sauger from the Mississippi River represented a small contribution to the Kaskaskia River Sauger stock; however, some fish showed evidence of moving between the Kaskaskia and Mississippi rivers. Similar water chemistry between the hatchery and Carlyle Lake prevented the identification of hatchery origin Sauger. Because the Sauger stock in the Kaskaskia River appears to be primarily supported by stocking of fish into Carlyle Lake or natural reproduction within the Kaskaskia River, fisheries managers should focus on quantifying the contribution of hatchery fish to the Kaskaskia River stock.

Thesis (M.S.)--Montana State University--Bozeman, 2006. / Title from PDF t.p. (viewed on Mar. 30, 2008). Chairperson, Graduate Committee: Christopher S. Guy. Includes bibliographical references (p. 65-72).

Lake Winnipeg has the second largest walleye fishery in North America. The North and South Basins of the lake differ in many ways, e.g. water temperature, turbidity, and fish community. The study objectives were to determine if (a) growth, condition or diet of walleye, sauger or dwarf walleye differed between basins, (b) among seasons, and (c) whether the invasive rainbow smelt are associated with these differences. Walleye, sauger and dwarf walleye were caught using gill-nets and analysed for growth, condition and diet in all seasons. Walleye and sauger in the North Basin showed higher growth rates and condition than in the South Basin. Diet in the South Basin had more diverse species composition, whereas in the North Basin, the diet consisted almost entirely of rainbow smelt. Some seasonal variation was also documented and the impact of rainbow smelt seems to be positive for these piscivorous fish in Lake Winnipeg.

Lake Winnipeg has the second largest walleye fishery in North America. The North and South Basins of the lake differ in many ways, e.g. water temperature, turbidity, and fish community. The study objectives were to determine if (a) growth, condition or diet of walleye, sauger or dwarf walleye differed between basins, (b) among seasons, and (c) whether the invasive rainbow smelt are associated with these differences. Walleye, sauger and dwarf walleye were caught using gill-nets and analysed for growth, condition and diet in all seasons. Walleye and sauger in the North Basin showed higher growth rates and condition than in the South Basin. Diet in the South Basin had more diverse species composition, whereas in the North Basin, the diet consisted almost entirely of rainbow smelt. Some seasonal variation was also documented and the impact of rainbow smelt seems to be positive for these piscivorous fish in Lake Winnipeg.

Environmental factors affect fish distribution and fisher behavior. These factors are seldom included in stock assessment models, resulting in potentially inaccurate fish abundance estimates. This study determined the impact of these factors using the commercial catch rate of sauger (Sander canadensis) and walleye (Sander vitreus) in Lake Winnipeg by: (1) the use of satellite data to monitor turbidity and its impact on catch via simple linear regression and (2) the effect of environment on catch and effort using generalized linear models. No statistically significant relationship was found between catch and turbidity; a result which may be due to small sample sizes, the fish species' examined, and variable turbidity at depth. Decreased effort was correlated with harsh weather and decreased walleye catch. Increased walleye catch was correlated with low temperature and low Red River discharge. Increased sauger catch was correlated with high temperature, high cloud opacity, and average Red River discharge.