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A Comparison of Methods to Estimate Shovelnose Sturgeon Mortality in the Mississippi River Adjacent to Missouri and Illinois

Quinton E. Phelps , Ivan Vining , David P. Herzog , Ross Dames , Vince H. Travnichek , Sara J. Tripp & Mark Boone.  2013. A Comparison of Methods to Estimate Shovelnose Sturgeon Mortality in the Mississippi River Adjacent to Missouri and Illinois, North American Journal of Fisheries Management, 33:4, 754-761, DOI: 10.1080/02755947.2013.808291.  Partially funded by the  U.S. Army Corps of Engineers' Upper Mississippi River Restoration-Environmental Management Program.

Abstract

The authors examined three methods to evaluate Shovelnose Sturgeon, Scaphirhynchus platorynchus, mortality.  Mortality is a key parameter in understanding the dynamics of any fish population.  The Mississippi River was sampled in two distinct but connected geomorphic sections: upper Mississippi River and the middle Mississippi River.  The three methods (e.g., ratio of first year recruits to all recruits [Heincke’s method], a linearized weighted catch curve, and an open system mark–recapture mortality approach) provided varying results, and our data indicated that a single method to estimate Shovlenose Sturgeon mortality rate may not be appropriate.  As such, biologists must recognize that disparities in Shovelnose Sturgeon mortality rates may exist using various methods and should use caution when choosing which method will be employed to estimate sturgeon mortality.   The authors suggest fishery management biologists use multiple mortality estimates (using several methods) in conjunction with ongoing monitoring of length-frequency and age-frequency distributions to ensure sustainability.  They also suggest developing a long-term standardized sampling program would allow cohorts to be followed over time, thus minimizing the assumptions associated with mortality estimates. Therefore, more accurate estimates of population parameters could be determined.

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