Otolith growth and age estimation in the European hake

The internal sulcal rings in Merluccius merluccius otoliths cannot be consi dered as annuli. In the absence of a strong seasonal Zeitgeber, bake otolit hs in the Mediterranean did nor lay down an interpretable ring pattern that would be useful for age determination. A total of 484 sagittal otoliths fr om specimens ranging between 6 and 94 cm L-T was studied in monthly samples from the Gulf of Lions in 1989-1990. Transverse, burnt otolith sections wa s analysed with an image analysis system using enhanced and filtered images and using a fast Fourier transform (FFT) function to avoid subjectivity in ring interpretation. The otolith radius-fish length relationship showed al lometric growth and sexual dimorphism. The ring pattern was consistent for the sulcal rings in both sexes. Changes in the marginal increment showed th e formation of multiple sulcal rings, of both environmental and physiologic al origin. The ring pattern depended on the sex and sexual activity. (C) 19 98 The Fisheries Society of the British Isles.