Matt Blank

Assessment of Trout Passage through Culverts in a Large Montana Drainage during Summer Low Flow

Abstract We used a combination of methods to assess the degree of fish passage restriction from road culverts during summer low flow for westslope cutthroat trout Oncorhynchus clarkii lewisi and brook trout Salvelinus fontinalis across a large drainage basin. The FishXing fish passage model classified 41 of 45 (91%) culverts as barriers to upstream passage for 152-mm westslope cutthroat trout. Population sampling upstream and downstream of 23 culverts revealed little differences in westslope cutthroat trout or brook trout above and below culverts, although density declined upstream when culvert slopes exceeded 4.5% and outlet drops exceeded 20 cm. A passage experiment with marked trout at 12 culverts showed that the proportion of upstream movement averaged 2.45 times lower through culverts (mean, 0.37) than through natural stream reaches (mean, 0.63; χ2 = 26.2, P < 0.001). Outlet drop was the most important factor affecting passage success; probability of passage was low for small trout (<100 mm fork leng...

Using historic aerial photography and paleohydrologic techniques to assess long-term ecological response to two Montana dam removals.

The restorative potential of dam removal on ecosystem function depends on the reversibility of dam effects and its operations. While dam removal is an established engineering practice, the need for an understanding of the ecological response remains. We used paleoflood hydrology, hydrologic modeling, and aerial photo interpretation to investigate the long-term ecologic responses to dam failure and breach. We investigated downstream geomorphic and vegetation responses to a dam failure (Pattengail Dam in 1927) and a controlled dam breach, which used natural sediment removal (Mystic Lake Dam in 1985). Our data showed vegetation responses indicative of channel and floodplain evolution at Pattengail. The size of the flood following the Pattengail dam failure initiated a series of channel adjustments and reworked over 19ha of floodplain downstream of the dam. In Mystic, we observed few flood stage indicators and a slight response in floodplain vegetation. We made several findings. (1) Dam removal effects on channel evolution and floodplain development depend on reach types and their responsiveness to flow regime change. (2) Ecologic response to dam removal depends on the sizes and timing of high flow events during and following removal. (3) Paleohydrology can be used to assess historic floods (>20 years). We see the utility of assessing the ecological responsiveness of a system to previous fluvial events or changes in flow regime. Informed about the character of a system based on its history, dam removal scientists can use these tools to set realistic restoration goals for removing a dam.

Evaluation of swimming performance for fish passage of longnose dace Rhinichthys cataractae using an experimental flume

The swimming performance of longnose dace Rhinichthys cataractae, the most widely distributed minnow (Cyprinidae) in North America, was assessed in relation to potential passage barriers. The study estimated passage success, maximum ascent distances and maximum sprint speed in an open-channel flume over a range of water velocities and temperatures (10·7, 15·3 and 19·3° C). Rhinichthys cataractae had high passage success (95%) in a 9·2 m flume section at mean test velocities of 39 and 64 cm s-1 , but success rate dropped to 66% at 78 cm s-1 . Only 20% of fish were able to ascend a 2·7 m section with a mean velocity of 122 cm s-1 . Rhinichthys cataractae actively selected low-velocity pathways located along the bottom and corners of the flume at all test velocities and adopted position-holding behaviour at higher water velocities. Mean volitional sprint speed was 174 cm s-1 when fish volitionally sprinted in areas of high water velocities. Swimming performance generally increased with water temperature and fish length. Based on these results, fishways with mean velocities <64 cm s-1 should allow passage of most R. cataractae. Water velocities >100 cm s-1 within structures should be limited to short distance (<1 m) and structures with velocities ≥158 cm s-1 would probably represent movement barriers. Study results highlighted the advantages of evaluating a multitude of swimming performance metrics in an open-channel flume, which can simulate the hydraulic features of fishways and allow for behavioural observations that can facilitate the design of effective passage structures.

Sprint Swimming Performance of Shovelnose Sturgeon in an Open-Channel Flume

Abstract The sprint swimming performance (Vmax) of twenty-five adult wild shovelnose sturgeon (Scaphirhynchus platorynchus) was studied in an outdoor experimental flume at four conditions consisting of two temperatures (12 °C and 19 °C) and two flows (High and Low). The fastest maximum velocity (Vmax) achieved in an individual trial was 3.73 m s-1, which is the greatest sprint velocity ever reported for a sturgeon species. The mean (SD) Vmax by trial was 2.94 (0.56) m s-1 for the Low Velocity 12 °C trial, 2.13 (0.50) m s-1 for the Low Velocity 19 °C trial, 3.01 (0.47) m s-1 for the High Velocity 12 °C trial, and 3.21 (0.88) m s-1 for the High Velocity 19 °C trial. We did not detect a statistically significant difference in swim speeds among the trials. Individual shovelnose sturgeon performed maximum sprint speeds ranging from 1.29 to 3.73 m s-1. Shovelnose sturgeon were able to reach maximum velocities for only a fraction of a second before returning to slower velocities, and often recorded multiple peaks in velocity throughout the course of a swim. The sprint velocities from our laboratory study indicate that the swimming capability of shovelnose sturgeon and possibly other sturgeon species is underestimated. The results of this study provide data that might support design and analysis of fish passage projects for shovelnose sturgeon and other sturgeon species.

Swimming Capabilities of Arctic Grayling

Abstract A native population of arctic grayling (Thymallus arcticus) exists in the upper Missouri River drainage of Montana. While formerly abundant, agricultural practices, predation, angling pressure, barriers to mobility, and competition from other species appear to be the causes of decreased presence of artic grayling in the Northwest (Skaar 1989). The purpose of this study was to augment the information base of the swimming ability of arctic grayling and to examine the effect of repeated trials using the same fish. Forty hatchery-raised grayling were separated into two cohorts and reared in an artificial stream. The mean fork length of all fish was 290 mm (SD ± 16). Cohort 1 was tested in a swim chamber experiment once per week for three consecutive weeks. Cohort 2 was tested only once in the swim chamber sixteen weeks later. Each fish was tested by placing it in the chamber initially operating at a low water velocity (30.5 cm s-1) and then regularly increasing the velocity until the fish rested on the screen at the downstream end of the chamber. The maximum water velocity against which each fish held its position was observed, and is reported as the sprint speed (Usprint). Overall the mean Usprint observed was 5.64 BL (body length) s-1 (SD ± 0.78) equal to an absolute velocity of 1.66 m s-1 (SD ± 0.19). Cohort 1 had a mean Usprint of 5.40 BL s-1 (1.62 m s-1) and Cohort 2 had a mean Usprint of 6.33 BL s-1 (1.77 m s-1). There were significant differences, and a generally increasing trend, in Usprint between the successive trials using Cohort 1.