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Abstract
The purpose of this study was to assess the validity of age estimates for the striped shiner Luxilus chrysocephalus and the duskystripe shiner Luxilus pilsbryi using asterisci otoliths, scales, and length data. Both species were sampled monthly from the headwater reaches of the James River in southwestern Missouri from February 1998 to January 1999. The formation of an annual opaque region was validated using edge analysis, whereby the progression of annulus formation is followed throughout the year. A single opaque region was formed in otoliths, primarily during May in striped shiners and June and July in duskystripe shiners. Agreement between otolith and scale ages was over 95% for fish 0–3 years old. However, scales commonly underestimated age for fish of ages greater than 3. For both species, the ages of individuals based on otoliths ranged from 0 to 6 years. Population age structure indicated higher rates of survival and longevity for females and faster growth rates for males of both species. The most notable life history differences between species were the accelerated growth rate of adult male striped shiners and the uniform age structure for female duskystripe shiners.
Received December 1, 2010; accepted December 15, 2011
ACKNOWLEDGMENTS
This manuscript is part of a master's thesis submitted to the Department of Biology at Missouri State University, Springfield. Thanks to Chris Barnhart and Don Moll for suggestions on the original version of the manuscript and to Christian Hutson, David Howlett, Michael Baird, and Frank Riusech for field assistance.