Morphological variation between juvenile white bass and juvenile hybrid striped bass

Authors

Ryan W. Lueckenhoff, University of Nebraska-LincolnFollow

Date of this Version

Spring 4-12-2011

Document Type

Article

Comments

A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In partial Fulfillment of Requirements For the Degree of Master of Science, Major: Natural Resource Sciences, Under the Supervision of Professor Kevin L. Pope. Lincoln, Nebraska: May 2011

Copyright 2011 Ryan W. Lueckenhoff

Abstract

While identifying recruitment bottlenecks for white bass Morone chrysops, we encountered difficulty distinguishing between age-0 white bass and age-0 hybrid striped bass M. saxatilis x chrysops. Accurate identification of juvenile white bass and hybrid striped bass will improve the quality of data gathered for research and monitoring efforts. The first objective of this study was to estimate biologists’ accuracy identifying juvenile white bass and juvenile hybrid striped bass, and to determine which characteristics biologists were using during identification. Overall, identification accuracy was 71%. Biologists who placed less emphasis using the characteristic "broken horizontal lines" or who examined >99 age-0 Morone spp. during the past 12 months had greater identification accuracy. The second objective of this study was to develop a simple technique to distinguish juvenile white bass from juvenile hybrid striped bass. Fish pictures were digitized and body morphology was quantified by multivariate discriminant function analysis. Overall, species-classification rate was high (99.6%). Juvenile white bass were longer 1) between lateral line and origin of spiny dorsal fin, 2) between anal fin and lateral line, and 3) in caudal peduncle depth. Juvenile hybrid striped bass were longer 1) in midsection body length and 2) in head size. The ratio of caudal peduncle depth to standard length (7.30) enabled us to distinguish between juvenile white bass and juvenile hybrid striped bass with an accuracy of 98.9%. Understanding which identification characteristics to use along with the application of quantifying fish body morphology will enable biologists to accurately distinguish between juvenile white bass and juvenile hybrid striped bass.