Guest Blog by FISHBIO from its Fish Report
Just when you think you’ve got a species figured out, sometimes they show up where they’re “not supposed to be” and make you reconsider. This recently happened in the fish world, when adult winter-run Chinook salmon, an endangered fish previously thought to only inhabit the mainstem Sacramento River downstream of Keswick Dam, were found to have actually reared in multiple Sacramento River tributaries as juveniles. A collaborative team of researchers made the discovery when they examined the otoliths, or “ear bones”, of returning adult winter-run, and identified where the fish had reared as juveniles by comparing ratios of strontium isotopes found in the water of various rivers to those in the fish’s otoliths. Their findings, recently published in the journal Biological Conservation, suggest that in a given year, as many as 65 percent of returning winter-run adults spent time in previously unknown rearing habitats as juveniles (Phillis et al. 2018). This makes these newly identified habitats critically important for the continued existence of winter-run Chinook salmon.
For the rest of the blog, visit: FISHBIO: Winter-Run Critical Habitat Conundrum.
