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What do you want to be when you grow up?

Posted on: May 18, 2012

Jan St Quintin operates the diamond cutter to prepare the otolith slice.

An astronaut? A ballerina? … An osteo-chronologist?

You can just see other people’s reaction during a casual conversation at a party can’t you?  “You’re a what?!”

So exactly what does the work of an osteo-chronologist entail?  You may be aware that the Department of Fisheries collects fish frames (the skeletal remains of a fish after it has been filleted) from recreational fishers.  Bony fish have tiny bones (or more correctly otoliths) located in their heads.  The bones are critical for hearing, balance and perception of depth for fish.  The bones are removed from the fish frame and then our osteo-chronologists step in. 

They set each otolith in a resin block that helps to protect the bone from chipping and keeps them stable when they are cut with diamond cutters to a thickness of less than a third of a millimetre.  Once the otoliths are cut, that very fine slice of the otolith is placed under a microscope … and then the fishes age secrets are revealed.  Otoliths display growth rings, similar to a tree trunk, which allow scientists to determine the age of the fish.  Find out more about the work of our brilliant osteo-chronologists in the Western Fisheries article, A Day in the Life of …

Want to try this out for yourself?  Try Activity 3: Counting Bands from the Marine WATERs Lesson Plan: What’s My Age Again? You can download the sectioned slides in a Powerpoint Presentation: Black Bream Sectioned Otoliths and challenge your class … the answers are included for you too!

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