Thorrold, S. R. Old Dominion University, sthorrol@odu.edu
Swart, P. K. University of Miami, pswart@rsmas.miami.edu

 
STABLE ISOTOPE AND TRACE ELEMENT MARKERS IN OTOLITHS: NATURAL TAGS OF NATAL LOCATION AND MIGRATION PATTERNS OF MARINE FISH
 
Fish otoliths are aragonitic accretions within the inner ear of teleost fishes. The periodic deposition of increments within otoliths, and the inert nature of the material once deposited, allows this information to be resolved at temporal scales approaching the daily level. Here, we demonstrate that the stable isotope (13C/12C and 18O/16O) and trace element composition (the "chemical signatures') of juvenile weakfish (Cynoscion regalis) otoliths are characteristic of the natal estuary in which the fish were spawned. The chemical signatures are specific enough to identify individual tributaries within Chesapeake Bay, and to place fish along the estuarine gradient within Delaware Bay. This suggests that chemical signatures in fish otoliths are sensitive to subtle changes in water chemistry. Otolith chemistry data from juvenile weakfish collected from a number of estuaries along the U.S. Atlantic coast were used to parameterize an artificial neural network that was capable of determining natal area of individual weakfish with classification accuracies of greater than 90%. These data provide unique information on connectivity rates among metapopulations of weakfish. This will, in turn, determine the optimal siting of marine reserves along this coast, and provide a powerful methodology for measuring the effectiveness of marine protected areas in the future.
 
Day: Wednesday, Feb. 3
Time: 11:00 - 11:15am
Location: Eldorado Hotel
 
Code: SS32WE1100E