Nesting Ecology of Spiny Softshell Turtles on the Missouri River in Montana: Zoogeographic and Management Implications

The nesting ecology of western spiny softshell turtles (Apolone spinifera hartwegi) in Montana, where they are at the northern extent of their range and a state Species of Concern, is poorly known. We used telemetry, visual surveys, observation from shore-based blinds, and remote cameras to document nesting behavior, habitat, and timing in a 97-km reach of the Missouri River. We located 25 nests in 2011 and 97 in 2012. Most nests were in mixed-gravel substrates; only 3 percent were in pure sand. Vegetative cover at nest sites was sparse. Mean distance of nests to the water’s edge was 13.7 m and mean height above the water surface elevation was 0.7 m. Proportion of nests found on island and mainland habitats were similar in 2011, but 90 percent of nests were on islands in 2012. Predation occurred on 46 nests; mainland nests incurred higher predation rates than island nests. Nesting followed annual peak river stage, and mostly occurred in the afternoon. Durations of nesting, incubation, and emergence periods were similar in both years, but nesting and emergence occurred about three weeks later in 2011 than in 2012. Only 36 percent of nests were successful in 2011, but 60 percent were successful in 2012. Flooding in 2011 probably decreased nesting effort and success by reducing habitat availability and delaying the onset of nesting, which thereby prematurely ended incubation. However, flood events maintain and create nesting habitats by clearing vegetation and depositing substrates. Premature termination of incubation suggests that the northern range of this species is probably limited by successful incubation

Nesting Habitat and Behavior of Spiny Softshell Turtles Apalone Spinifera Hartwegi in the Missouri River, MT

Little is known about the nesting behavior and habitat of the western spiny softshell (Apalone spinifera hartwegi) in Montana where they are at the northern extent of their range and are a state Species of Concern. Our objective was to document nesting behavior, habitat, and timing in a 97-kilometer reach of the Missouri River. We radio-tagged 47 female turtles and attempted to locate nesting areas using telemetry, visual surveys from jet boat and on foot, and by observation from shore-based blinds. We located 27 nests; 15 were on islands, 12 were aggregated, and 2 were depredated. Nesting occurred following the peak river stage from about July 7 to July 28. Twenty-three nests were in mixed gravel and 4 nests were in sand substrates. Distance from water’s edge to the nest ranged from 1.9 m to 27 m and height of nest above the water surface elevation ranged from 0.25 m to 1.9 m. Vegetation at nest sites was sparse, ranging from 0 to 15 percent vegetative cover. Emergence of hatchlings was documented for 17 nests and occurred from about September 1 to September 20. All 17 successful nests were in gravel substrate; we did not document any emergence from nests in sand. Lack of emergence from sand nests may be related to the cumulative thermal regime in the nest chamber during the period from peak discharge until the onset of freezing in autumn. In 2012, we will investigate the thermal environment in gravel and sand nesting substrates

Nesting Ecology of Spiny Softshell Turtles on the Missouri River in Montana: Zoogeographic and Management Implications

The nesting ecology of western spiny softshell turtles (Apolone spinifera hartwegi) in Montana, where they are at the northern extent of their range and a state Species of Concern, is poorly known. We used telemetry, visual surveys, observation from shore-based blinds, and remote cameras to document nesting behavior, habitat, and timing in a 97-km reach of the Missouri River. We located 25 nests in 2011 and 97 in 2012. Most nests were in mixed-gravel substrates; only 3 percent were in pure sand. Vegetative cover at nest sites was sparse. Mean distance of nests to the water’s edge was 13.7 m and mean height above the water surface elevation was 0.7 m. Proportion of nests found on island and mainland habitats were similar in 2011, but 90 percent of nests were on islands in 2012. Predation occurred on 46 nests; mainland nests incurred higher predation rates than island nests. Nesting followed annual peak river stage, and mostly occurred in the afternoon. Durations of nesting, incubation, and emergence periods were similar in both years, but nesting and emergence occurred about three weeks later in 2011 than in 2012. Only 36 percent of nests were successful in 2011, but 60 percent were successful in 2012. Flooding in 2011 probably decreased nesting effort and success by reducing habitat availability and delaying the onset of nesting, which thereby prematurely ended incubation. However, flood events maintain and create nesting habitats by clearing vegetation and depositing substrates. Premature termination of incubation suggests that the northern range of this species is probably limited by successful incubation

Cumulative Effects of Micro-Hydro Development on the Fisheries of the Swan River Drainage, Montana: Volume 2, Technical Information, 1983-1984 Final Report.

This report summarizes a study to determine the potential cumulative effects of proposed small hydro development on the fisheries of the Swan River drainage. This report contains technical information and is a support document for the main report (Leathe and Enk, 1985). Consequently, discussion of results was minimized. The sections on fish population monitoring, streambed monitoring, habitat survey comparisons, and water temperature are the only portions that were not discussed in the main report. 5 refs., 55 figs., 44 tabs

Cumulative Effects of Micro-Hydro Development on the Fisheries of the Swan River Drainage, Montana: Volume 3, Fish and Habitat Inventory of Tributary Streams, 1983-1984 Final Report.

This report summarizes a study of the fisheries of the Swan River drainage in relation to potential small hydro development. This information was collected in order to obtain a reliable basin-wide database which was used to evaluate the potential cumulative effects of a number of proposed small hydro developments on the fisheries of the drainage. For each named tributary stream there is a reach-by-reach narrative summary of general habitat characteristics, outstanding features of the stream, and fish populations and spawning use. An attempt was made to rank many of the measured parameters relative to other surveyed stream reaches in the drainage. 3 refs

Cumulative Effects of Micro-Hydro Development on the Fisheries of the Swan River Drainage, Montana, Volume I, Summary, 1983-1984 Final Report.

This study was designed to develop and apply methods to evaluate the cumulative effects of 20 proposed small hydro projects on the fisheries resources of the Swan River drainage located in northwestern Montana. Fish population and reach classification information was used to estimate total populations of 107,000 brook trout, 65,000 cut-throat trout and 31,000 juvenile bull trout within the tributary system. Distribution, abundance, and life history of fish species in the drainage and their contribution to the sport fishery were considered in the cumulative impact analysis. Bull trout were chosen as the primary species of concern because of their extensive use of project areas, sensitivity to streambed sedimentation, and their importance to the lake and river sport fisheries. Dewatering of hydroelectric diversion zones and streambed sedimentation (resulting from forest and small hydro development) were the major impacts considered. The developer proposed to divert up to the entire streamflow during low flow months because maintenance of recommended minimum bypass flows would not allow profitable project operation. Dewatering was assumed to result in a total loss of fish production in these areas. 105 refs., 19 figs., 38 tabs

Cumulative Effects of Micro-Hydro Development on the Fisheries of the Swan River Drainage, Montana, First Annual Progress Report (Covering Field Season July-November 1982).

This fisheries study is to determine the potential cumulative biological and economic effects of 20 small or micro-hydro-electric facilities (less than 5 megawatts) proposed to be constructed on tributaries to the Swan River, a 1738 square kilometer (671 square mile) drainage located in northwestern Montana. The study addresses portions of measure 1204 (b) (2) of the Norwthwest Power Planning Council's Columbia River Basin Fish and Wildlife Program. Aerial pre-surveys conducted during 1982 identified 102 stream reaches that may support fish populations in the Swan drainage between Swan and Lindbergh lakes. These reaches were located in 49 tributary streams and constituted 416 kilometers (258 miles) of potential fish habitat. Construction of all proposed small hydro projects would divert water from 54 kilometers (34 miles) or about 13 percent of the tributary system. Only two of the 20 proposed hydro sites did not support trout populations and most were populated by migratory bull trout and westslope cutthroat trout. Potential cumulative habitat losses that could result from dewatering of all proposed project areas were predicted using a stream reach classification scheme involving stream gradient, drainage ara, and fish population data. Preliminary results of this worst case analysis indicate that 23, 19 and 6 percent of the high quality rearing habitat for cutthroat, bull, and brook trout respectively would be lost

A Literature evaluation of Montana\u27s wetted perimeter inflection point method for deriving instream flow recommendations /

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