UNK Chapter of Sigma Xi: The Scientific Research Society
Monday, August 27, 2012
The Loft at Cunningham’s Journal
15 West 23rd Street
Percid sexual-size dimorphism: causes and management considerations
Dr. Casey W. Schoenebeck
Department of Biology
University of Nebraska at Kearney
Dr. Schoenebeck is an Assistant Professor in the Department of Biology with a split commitment to our online MS Biology Program and fisheries research in cooperation with the Nebraska Game and Parks Commission. His research uses novel ecological tools to answer applied fisheries questions.
Size-selective angler behavior or the implementation of length based regulations may have implications in harvest oriented yellow perch (Perca flavescens) fisheries where perch populations display sexual-size dimorphism (SSD), which is defined as higher female growth rates and greater maximum attainable lengths. Predicted mean lengths at age from four states and one Canadian province were significantly greater for female yellow perch after age-3 indicating female-biased SSD occurred upon maturity. Because yellow perch anglers are size selective for larger individuals and harvest oriented, the occurrence of female-biased SSD in a perch population will likely result in female-biasedexploitation (more females harvested and thus removed from the population). To understand the cause of SSD, I quantified the glycolytic muscle enzyme lactate dehydrogenase (LDH, an index of recent anaerobic activity) to determine if enzyme concentrations differed between sexes in yellow perch populations that exhibit female-biased SSD. The hypothesis was higher male activity (as indexed by LDH) could explain the slower somatic growth in males as energy is allocated to locomotion instead of growth. Male yellow perch LDH concentrations were greater than female LDH concentrations supporting the hypothesis and offering an explanation for female-biased SSD in yellow perch.