Sean Brennan, a former University of Utah grad student in biology, has just published a new study on Pacific salmon in the journal Science Advances. It is reportedly the largest study yet on the travels of salmon in Alaska.
Brennan, currently a post doctorate student at the University of Washington, traveled along a large section of the Nushagak River in Western Alaska over a period of three years gathering the otolith or ear bone from 255 Chinook salmon. He noted that “every fish has this little chemical recorder inside its head that is a boon to scientists who are interested in reconstructing those movement patterns for different conservation issues.”
University of Utah associate professor of geology and geophysics and study co-author, Diego Fernandez, explained that they actually cut through each layer of each ear bone utilizing laser ablation. This enabled them to create an intricate map of the specific travel routes of each salmon as well as the time they spent at each location.
Fernandez elaborates: “Each season you add a new layer so you end up with something that looks like a tree ring in the sense that it has like bands. Going from the center to the outside of the bone you are basically following all the life history of the fish.”
Distinguished professor of geology, geophysics and biology at the University of Utah and co-author of the study, Thure Cerling noted that what Brennan did was remarkable as there are no trails or roads close to the watersheds. He states: “What Sean did that was different than anyone else was to analyze so many samples that you could begin to think about this at a population level.”
Brennan feels lucky to have been able to analyze “such a complex organism” and he hopes the study can aid in protecting the salmon as well as its habitat. He also acknowledged the assistance he received from the local residents concluding: “The local people on the Nushagak River are welcoming and we worked closely with the folks that actually live in the watershed and their help along the way was invaluable.”
Pacific Salmon Tracked In Huge Study