PARENT SESSION
Tuesday, August 8, 5:00-6:30 pm
Poster Session 8 - Aquatic ecology
Exhibit Hall, Ballroom Level, Cook Convention Center

Dispersal of age-1 smallmouth bass determined from elemental chemistry of otoliths.

Priest, Brant^*,1, Humston, Robert¹, Bugas, Paul², ¹ Virginia Military Institute, Lexington, VA, USA² Department of Game and Inland Fisheries, Verona, VA, USA

ABSTRACT- Tracking dispersal of young of year (YOY) stream fishes away from their spawning locations is important to understand in river-tributary systems because of its potential effect on population dynamics. Dispersal may occur as a result of high flow events in which currents can carry YOY's substantial distances downstream from their spawning location and into adjoining rivers. Traditional methods for tracking movement are generally not efficient for characterizing these events. In 2005 we analyzed otolith trace element chemistry of YOY smallmouth bass (Micropterus dolomieu) from the James River and one of its tributaries (Maury River) as a means of discriminating natal origins of fish within and between rivers. Trace element concentrations in whole otoliths extracted from 3-6 week old smallmouth bass fry were determined using solution-based ICP-MS. The YOY smallmouth bass were classified to their natal river with accuracy ranging from 90%-100% using parametric and non-parametric classification methods. Specific reaches (river segments) of origin within the rivers were discriminated with 65%-97% accuracy. We compared chemistry from the core of age-1 smallmouth bass otoliths with chemical 'signatures' of natal areas identified from YOY otoliths in the previous year. This provides an indication of dispersal in the first year of life. We summarize these results and discuss their implications for understanding the influence of hydrologic variation on recruitment dynamics in lotic fish populations.

Key words: dispersal, otolith chemistry, river fisheries