Endangered and Threatened Species of the Platte River (2005) / Chapter Skim
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7 Pallid Sturgeon
7 Pallid Sturgeon
Pages 225-239
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From page 225... ...
The segment of the lower Platte River of inter est in this question extends downstream from the confluence of the Elkhorn River with the lower Platte to the mouth of the lower Platte at its confluence with the Missouri River. Sturgeons (family Acipenseridae)
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From page 226... ...
In Kansas, they are known only from the lower 65 km of the Kansas River, mostly during the time of floods. In Nebraska, they have been captured up to 46 km upstream of the mouth of the Platte River.
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From page 227... ...
sturgeon in the Missouri River drainage is disjunct, with a northern subpopulation in Montana that is associated with the Yellowstone River confluence and another subpopulation downstream of the Gavins Point Dam near Yankton, South Dakota. In this lower section of the Missouri River drainage, the Platte River is the only tributary from which pallid sturgeon have been captured regularly in the last 20 years.
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From page 228... ...
In the Platte River, catches of pallid sturgeon are uncommon but occur regularly. In 1979-2002, anglers reported catching pallid sturgeon in the Platte and Elkhorn Rivers.
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From page 229... ...
No spawning areas have been documented, and no trend data exist for pallid sturgeon, but Scaphirhynchus sp. larvae have been collected from the lower Platte River.
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From page 230... ...
Although there is no direct evidence of pallid sturgeon spawning in the lower Platte River, a female carrying a large quantity of eggs was captured on May 3, 2001, and a radiotransmitter was implanted in her. She remained in the lower Platte River for more than a month before moving back to the Missouri River in early June 2001.
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From page 231... ...
, the Mississippi River by Hurley (1999) , and the lower Platte River by Snook et al.
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From page 232... ...
In the Platte River, Nebraska, wild pallid sturgeon were captured in habitats with a mean column velocity of 0.82 m/s in 2001 and a range of 0.38-0.65 m/s in 2002 (Ed Peters, University of Nebraska, unpublished material, May 2, 2001, and May 23, 2002 )
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From page 233... ...
. Suspended-solids concentrations at locations where wild pallid sturgeon were captured in the lower Platte River range from 313 to 359 mg/L (Swigle 2003)
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From page 234... ...
There are no other known habitats for pallid sturgeon in tributaries of the lower Platte River system or in nearby Missouri River tributaries. For those reasons, the lower Platte River may be even more important for the recovery of pallid sturgeon.
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From page 235... ...
. The mouth of the Platte River is included in recovery priority management area 4.
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From page 236... ...
Because of low population densities and rather recent initiation of regular sturgeon sampling, it has not been determined what role the Platte plays in the ultimate recovery of pallid sturgeon in the middle and lower Missouri River population. Today, the lower Platte receives water from the central Platte and three main tributaries -- the Loup system, the Elkhorn system,
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From page 237... ...
Although there is no recorded documentation of pallid sturgeon reproduction in the lower Platte River, it seems to be the tributary of the lower Missouri River most likely to have the combination of discharge, substrate, and channel morphometry necessary for spawning to occur. There is recent evidence that sturgeon are spawning on sand and gravel bars in the lower Missouri River and the Mississippi River.
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From page 238... ...
It is clear that the lower Platte River by itself can be only a part of the overall recovery of the lower Missouri River population of the pallid sturgeon. Continued efforts to expand appropriate habitats for spawning, overwintering, development, and maturation of pallid sturgeon that will increase the overall population are urgently needed.
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From page 239... ...
How do proposed modifications along the Platte River affect flow patterns and instream habitat in the river? The habitat in the lower Platte River needs to be evaluated with models that more accurately predict channel responses to altered river management.
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