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The otoliths, after being cleaned in alcohol and xyoll, are stored dry. The following manipulations are most useful for distinguishing the growth zones: 1. the otolith is ground on its convex surface; 2. then it is broken into two halves through the nucleus and is soaked in concentrated glycerine for about 24 hours; and 3. both halves are heated in a bunsen flame for approximately two minutes until they are dark brown. Thus prepared otoliths are examined in reflected light under a stereoscopic microscope at 25-50X magnification. Alternating dark brown and yellow zones show the age.
