The following schedule is from the 72nd Annual Conference of the Southeastern Association of Fish & Wildlife Agencies which was held October 21-24, 2018 in Mobile, Alabama.
AUTHORS: Peter C. Sakaris, Jesse J. Sunga, Jessica N. Coover – Georgia Gwinnett College
ABSTRACT: As human populations grow and expand in urban landscapes, we need to strengthen our understanding of how anthropogenic activities that degrade instream habitats affect the life history and ecology of fishes in urban streams. Population-level studies typically require age estimation of fish, but populations in small rivers and streams are generally smaller than those in large rivers or reservoirs. Therefore, non-lethal aging methods are recommended to minimize the potentially negative effects of sampling on population size. Accordingly, our main goal was to compare otoliths and scales as structures for estimating the age of redbreast sunfish and green sunfish in an urban watershed. Reader agreement was greater for otoliths (88-89%) than for scales (73-79%) for both species, and reader bias was greater for scales than otoliths. Readers were significantly more confident in their aging of otoliths versus scales. In general, scales overestimated the otolith-derived ages of young fish, and underestimated the otolith-derived ages of old individuals. Mean estimated ages were not significantly different between otolith-based and scale-based ages for both species, and population age structure histograms were generally similar between structures. Scales underestimated maximum age by one year for the redbreast sunfish and two years for the green sunfish. Our assessment also indicated that annual survival estimates derived from catch-curve analyses may differ between otoliths and scales. We recommend that biologists use scales to estimate the ages of redbreast sunfish and green sunfish, but only when a non-lethal aging method is required and/or small populations are being assessed.
