Natural Recruitment Potential of a Reintroduced Shovelnose Sturgeon Population in the Bighorn River, Wyoming

Abstract.—Fish ladder designs that pass adult sturgeons are poorly studied. This is partly due to difficulties associated with obtaining and testing large adults. To learn about behavior and swimming of sturgeons in fish ladder environments, we observed juvenile lake sturgeon Acipenser fulvescens to determine the type of ladder opening that fish passed best. We also constructed a short fish ladder (6% slope) using the best opening type and determined the general usefulness of the ladder design to pass juvenile lake sturgeon, pallid sturgeon Scaphirhynchus albus and shovelnose sturgeon S. platorynchus. Lake sturgeon swam upstream through orifice and vertical openings better than through surface weir or weir and orifice openings. Because 37% of the fish hit the orifice when swimming upstream, and also, sturgeon could be damaged passing downstream through an orifice, we focused on testing a ladder design with vertical openings. A side-baffle ladder design that created vertical openings that alternated from side to side showed promise at passing the three species of sturgeons. All lake sturgeons (N = 15), most pallid sturgeons (12 of 22 fish, 55%), and 1 of 3 shovelnose sturgeons ascended the side-baffle design. Also, all sturgeon species moved safely downstream in the side-baffle ladder by passively drifting tail-first. Mean velocity in side-baffle openings was 60–75 cm/s, so sturgeons could use prolonged swimming speed to swim upstream. Vertical openings were wide enough for fish to partially erect their pectoral fins, likely a critical factor for maintaining balance. Our observations suggest that a ladder for adults should have vertical openings, enable fish to swim continuously and not stop at cross-channel barriers, have resting areas, enable fish to safely drift downstream, and enable fish to swim upstream using prolonged swim speed. The study of juvenile sturgeon behavior and swimming ability can contribute to developing a fish ladder for adults. This approach to fish ladder development can be used for other species with large adults.

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Biology, Management, and Protection of North American Sturgeon

Biology, Management, and Protection of North American Sturgeon ◽

10.47886/9781888569360.ch20 ◽

2002 ◽

Keyword(s):

Distinct Species ◽

Current Status ◽

Valid Species ◽

Morphological Evidence ◽

Morphometric Character ◽

Meristic Characters ◽

Shovelnose Sturgeon ◽

Major Threat ◽

Pallid Sturgeon ◽

Two Indices

Abstract.—It is difficult to distinguish pallid sturgeon Scaphirhynchus albus from the morphologically similar, congeneric and sympatric shovelnose sturgeon S. platorynchus. This has led some to question whether the pallid sturgeon is indeed a valid species. Another controversy is whether the two species are hybridizing. Indices, based on various morphometric and meristic characters, have been proposed to discriminate among Scaphirhynchus taxa, but they are cumbersome to calculate in the field. We report two mathematical indices developed via multiple regression analysis that use five morphometric ratios and two meristics (Character Index), or the five morphometric ratios alone (Morphometric Character Index) as taxon predictors. Data from a study of pallid sturgeon and shovelnose sturgeon conducted by Carlson and Pflieger (1981) were used to develop the regression models. The consistency of identifications made by the two indices was examined using Discriminant Functions Analysis (DFA) on a collection of 257 Scaphirhynchus specimens from throughout the pallid sturgeon range. Specimens identified via the CI and mCI as pallid sturgeon grouped distinctly from the shovelnose sturgeon cluster; specimens identified as hybrids by the two indices formed an intermediate cluster. The majority (90% and 89.7%, respectively) of the specimens identified as pallid sturgeon by the Character Index (CI) and the Morphometric Character Index (mCI) were classified as pallid sturgeon by DFA. This morphological evidence supports the current status of pallid sturgeon and shovelnose sturgeon as distinct species. Interspecific hybridization, considered by some to be a major threat to the pallid sturgeon, appears to be common. The Pallid Sturgeon Recovery Team has recommended the CI for field identifications throughout the pallid sturgeon’s range.

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Effect of Morphological Fin-Curl on the Swimming Performance and Station-Holding Ability of Juvenile Shovelnose Sturgeon

Journal of Fish and Wildlife Management ◽

10.3996/092015-jfwm-087 ◽

2016 ◽

Vol 7 (1) ◽

pp. 198-204 ◽

Cited By ~ 2

Author(s):

David Deslauriers ◽

Ryan Johnston ◽

Steven R. Chipps

Keyword(s):

Swimming Speed ◽

Early Onset ◽

Positive Relationship ◽

Swimming Performance ◽

Fork Length ◽

Critical Swimming Speed ◽

Pectoral Fin ◽

Speed Test ◽

Shovelnose Sturgeon ◽

Pectoral Fins

Abstract We assessed the effect of fin-curl on the swimming and station-holding ability of juvenile shovelnose sturgeon Scaphirhynchus platorynchus (mean fork length = 17 cm; mean weight = 16 g; n = 21) using a critical swimming speed test performed in a small swim chamber (90 L) at 20°C. We quantified fin-curl severity using the pectoral fin index. Results showed a positive relationship between pectoral fin index and critical swimming speed indicative of reduced swimming performance displayed by fish afflicted with a pectoral fin index < 8%. Fin-curl severity, however, did not affect the station-holding ability of individual fish. Rather, fish affected with severe fin-curl were likely unable to use their pectoral fins to position their body adequately in the water column, which led to the early onset of fatigue. Results generated from this study should serve as an important consideration for future stocking practices.

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