Distribution, Density, Movement, and Support for Management of Mountain Sucker, \u3cem\u3ePantosteus jordani\u3c/em\u3e, in the Black Hills of South Dakota

Mountain Sucker, Pantosteus jordani, is a cold-water species native to the Intermountain West. Fringe populations of Mountain Sucker have experienced declines in recent decades. The population of Mountain Sucker found in the Black Hills of South Dakota represents the eastern fringe of the species’ native range. Recognized as both an indicator of biologic health and as a species of greatest conservation need in South Dakota, recent studies have suggested significant declines in both distribution and abundance. Despite the recent study of Mountain Sucker in the region, increased understanding of Mountain Sucker ecology is needed to effectively manage for the conservation of this species. First, I assessed public perceptions towards the management of non-game, native species in the region. Traditional stream management has focused on the proliferation of non-native salmonids due to their recreational and economic value. Public support for management was generally positive for residents of the Black Hills region. Next, I assessed the general movements of Mountain Sucker. General movements were small, indicating high-sight fidelity and limited potential for recolonization of streams and locations where they have been extirpated. Third, we examined segment-scale habitat variable to predict distribution of Mountain Sucker throughout the Black Hills stream network in South Dakota. Previous work identified the importance of stream permanency in influencing Mountain Sucker occurrence, our results indicated that Mountains Sucker distributions were primarily impacted by mean August stream temperatures at the segment scale. We assessed the current distribution of Mountain Sucker in the Black Hills of South Dakota for comparison with the findings of the most recent research. Mountain Sucker were found in more drainages and at more locations than in the previous study, likely a result of increased detection probabilities associated with more intensive survey designs and repeated site visits. Finally, we assessed 25-year trends in Mountain Sucker density in historically sampled locations. General trends in density were negative; however, significant trends were only observed in three locations. Mountain Sucker appear to have been extirpated from three streams since the most resent assessment. Several sampling locations included high densities of Mountain Sucker that could serve as source populations for restoration efforts via translocation. Overall, this research provides insight into the status of Mountain Sucker in the Black Hills of South Dakota, and the level of public support of active management of this regionally imperiled species. Managers can use this information to guide potential conservation efforts, such as translocations

Factors affecting the catch and harvest rates of paddlefish downstream of Gavins Point Dam, South Dakota, 2000–2020

Paddlefish, Polyodon spathula (Walbaum), provide an important snagging and bowfishing fishery below Gavins Point Dam in South Dakota. During 2009–2020, snagging catch rates of paddlefish decreased below Gavins Point Dam to presumed “normal” lower pre-2004 levels, while bowfishing catch (harvest) rates significantly increased during 2000–2020. Because Paddlefish are highly migratory, both local (i.e., monthly gauge height, precipitation, and air temperature near Gavins Point Dam) and remote (difference in Mississippi and Missouri River discharge near their confluence) environmental conditions were used to explain variation in snagging catch rates and bowfishing harvest rates. Snagging catch rates were related to October gauge height, whereby deeper water in October led to decreased catch rates below Gavins Point Dam. Bowfishing harvest rates increased significantly after a 2016 regulation change moved the season from July 1 to July 31, and from June 1 to June 30, likely because water clarity was greater in June than in July. Mean annual air temperature and precipitation explained variation in bowfishing harvest rates prior to the 2016 regulation change. Our findings, the first to examine both snagging and bowfishing fisheries below Gavins Point Dam, suggest that local abiotic factors are likely more important than remote discharge for explaining variation in snagging catch rates and bowfishing harvest rates in the channelised Missouri River