Methods of ageing red gurnard (Teleosti: Triglidae) by fin rays and otoliths

Abstract

Methods for ageing red gurnard, Chelidonichthys kumu (Lesson and Garnot), using the growth zones shown by fin rays and otoliths are described. Several preparation techniques are compared; sectioned fin rays and heated otoliths, both read in xylol using reflected light, were the most successful, the otoliths giving the most consistent results. The validity of using growth zones for ageing is checked by examining the pattern and time of zone formation in the otoliths. Length frequency analysis is not adequate for ageing but can be used as a check to the reading of skeletal structures of smaller fish. The time of first ring formation as it affects age designation is discussed.