Assessing Migratory Habits of Southern Flounder Using Otolith Chemistry

LA-ICP-MS analysis of fish otoliths ("earstones") such as the one pictured at left (in cross section) is used to extract information about the age and growth history of fish, much as scientists use tree rings to learn about trees.

Benjamin Walther & Megan Nims, UT Marine Science Institute

Project summary:

Because some trace elements vary predictably across salinity gradients, and these elements can be reliably incorporated into biogenic carbonates such as fish ear stones (otoliths), we can reconstruct fish movements in estuaries using laser ablation ICP-MS.  This project examined movements of southern flounder, an ecologically and economically important species in the Gulf of Mexico.  We sampled estuarine and fresh waters to quantify spatiotemporal variations in trace element composition for numerous tributaries in the South Texas Coastal Bend using solution-based ICP-MS, and then used laser ablation to characterize elemental variability across otoliths for approx. 260 southern flounder.  Contrary to prior expectations, a large proportion of flounder do not move into low salinity waters during their early life histories.  Laser ablation thus allows us to refine our understanding of life history strategies for important migratory species.

Link to CNS article:

http://web5.cns.utexas.edu/news/2012/10/secret-lives-fish-otolith-chemisty/