Sean Brennan Kayaking in Alaska (IMAGE) University of Utah Caption Biologist Sean Brennan paddles his equipment-laden kayak during a study that developed a new way to use strontium isotope ratios in 'fish ear bones' of chinook salmon caught at sea to identify in what streams within Alaska's Nushagak River watershed the fish hatched and lived before migrating to Bristol Bay and the Pacific. Brennan, a University of Utah biology graduate, did the study as a doctoral student at the University of Alaska Fairbanks and performed the lab work in Utah. He now is a postdoctoral researcher at the University of Washington. Credit Jesse Davis Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.