Fishery managers must be able to distinguish between various spawning populations in order to assess the impact of their work on fishable populations. Researchers from Ohio State University’s Aquatic Ecology Laboratory built upon a tried and true method to study walleye that have posed a challenge to traditional identification techniques.
When fishery researchers want to determine the origin and stock of a fish, they often analyze the otolith, or ear bone, of the specimen, looking for signs of the unique chemical “fingerprint” left by their birth river. Otolith-based identification tends to fail on fish populations that leave their birth river in a matter of days, however, as the water’s chemical signature doesn’t have time to leave a mark on the fish.
Using lasers and plasma mass spectrometry, the researchers obtained more precise readings on the otoliths of walleye as young as two days old. Their findings, presented at the 2014 American Fisheries Society annual meeting, provide fishery managers with a uniform means of identifying both fish larvae and adults.