PARENT SESSION
Poster Session 27: Fish Ecology
Thursday, August 11, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Using otolith microchemistry to determine natal origins of individuals in lotic fisheries.
Humston, Robert*,1, Hamilton, William1, Bugas, Paul2, 1 Virginia Military Institute, Lexington, VA, 244502 Virginia Department of Game and Inland Fisheries, Verona, VA, 24482
ABSTRACT- Smallmouth bass (Micropterus dolomieu) populations show a high degree of spatial structure, including repeated use of seasonally-distinct home ranges. It has been hypothesized that spatial structure results from density-dependent dispersal in the mid-juvenile stage, where individuals disperse away from their natal area in response to conspecific competition. We analyzed trace element chemistry of young of the year (YOY) smallmouth bass from a high-order river (James River, Virginia) and a lower order tributary (Maury River) to determine if chemical signatures can distinguish between natal rivers of YOY fish. Otoliths of older fish can subsequently be analyzed at specific points along the axis of accretion (i.e., growth) to identify occurrence and timing of dispersal away from their natal river. Cluster analysis of water chemistry data indicates that Euclidean distances between multivariate chemical signatures of the two rivers is sufficient to induce distinguishable differences in otolith chemistries. Chemical analyses of YOY otoliths by solution-based and laser ablation ICP-MS is underway; discriminant function analysis will be used to determine if chemical signatures can distinguish YOY samples between rivers. We will report on the results of these analyses and their implications for quantifying dispersal and connectivity in lotic metapopulations.
Key words: dispersal, otolith microchemistry, metapopulation, stream fish