Shovelnose Sturgeon - Scaphirhynchus platorynchus
The smallest and most common sturgeon in Montana is the shovelnose sturgeon. It reaches a maximum weight of about 15 pounds. These fish can readily be taken on bait fished on the bottom and are pursued by relatively few anglers in the Missouri River downstream from Great Falls.
Dorsal fin has 30 to 36 rays; anal fin has 18 to 23 rays.
Western Hemisphere Range
Summary of Observations Submitted for Montana
Number of Observations:
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(Observations spanning multiple months or years are excluded from time charts)
Long seasonal spawning movement from lower Missouri River upstream to mouth of Marias River. Dispersal downstream follows spawning (Berg 1981). This differs from the Yellowstone River where fish were somewhat concentrated in two areas in spring but dispersed the rest of the year throughout the Yellowstone and lower Missouri Rivers (Bramblett 1996).
Large rivers over sand or gravel, often in strong current; also impoundments of these rivers. Tolerates turbid water. (FWP) In Montana, shovelnose sturgeon appear to utilize primarily large rivers (Bramblett 1996), but also use reservoirs to some extent. They are found in all channel types, primarily in straight reaches with islands (Bramblett 1996). They are found at depths ranging from 0.9 to 10.1 m and averaged 2.29 m (Bramblett 1996). Channel widths used are from 25 to 800 m, and averaged 208 m (Bramblett 1996). Bottom velocities range from 0.00-1.51 m/s, and average 0.78 m/s in riverine habitat (Bramblett 1996). They tolerate high turbidity. Spawning substrate is silt-free gravel bars; preferred substrate use year-long is primarily gravel and cobble (69%), while fines and sand (27%) are avoided (Bramblett 1996). However, small sturgeon (<5kg) may use areas over larger substrates (Erickson 1992).
Studies on middle Missouri River showed two species of mayflies comprising 58% of summer diet (Berg 1981). May occasionally feed on planktonic organisms (Brown 1971).
Annual home ranges for shovelnose sturgeon in Montana ranged from 0.0 to 254.1 km with a median of 35 km; seasonal home ranges were smallest in winter and largest in summer (Bramblett 1996). Sturgeon were found to have moved 78% of the time between relocations; they moved up to 15.0 km/day and 6.6 km/hr (Bramblett 1996). The minimum flow required to trigger spawning migrations into the Tongue R. is between 500 - 600 cfs while optimum spawning flow is 1000 + cfs.
Lower Marias, Tongue, and Powder River are important spawning areas in Montana. Spawns from May - early July at 60 - 70 degrees F. Eggs hatch in 1 week. Spawning peaks early June in middle Missouri River (Brown 1971, Berg 1981, Penkal 1981).