image: Photograph of an adult Chinook salmon's otolith still within its endolymphatic sac (photo taken by Sean Brennan); this individual was harvested in Nushagak Bay in 2011 and was one of the individuals analyzed in this study. Dissolved strontium ions present within the ambient water in which fish live pass through the fish's gills, into its blood, then into the fluid within the endolymphatic sac, and then are ultimately deposited onto the surface of the otolith. The otolith grows via concentric rings of calcium carbonate, which are metabolically inert once formed. This material relates to a paper that appeared in the May 15, 2015, issue of Science, published by AAAS. The paper, by S.R. Brennan at the University of Alaska, Fairbanks in Fairbanks, AK, and colleagues was titled, 'Strontium isotopes delineate fine-scale natal origins and migration histories of Pacific salmon.' view more
Credit: [Credit: Sean Brennan]