PATTERNS OF INCREMENT WIDTH AND STRONTIUM - CALCIUM RATIOS IN OTOLITHS OF JUVENILE ROCK BLACKFISH, GIRELLA-ELEVATA (M)

Otoliths of juvenile Girella elevata (M.) were examined to obtain information about the environmental conditions experienced during early life. Patterns of increment deposition and elemental ratios in otoliths were compared in wild fish. A tetracycline experiment indicated that increments were deposited daily in juveniles. Although different patterns in the spacing of increments were found among juveniles collected at different locations and times, the widest increments were always found in the first 40 increments. Strontium: calcium (Sr: Ca) ratios increased with age in the otoliths of most wild G. elevata. The patterns of increment width and Sr: Ca ratios were not related and, therefore, were probably not under the same relative control by environmental or physiological factors. Although the number of increments can be used to age juvenile G. elevata, the utility of increment widths and Sr: Ca ratios as environmental predictors in this species is questionable without experimental validation. Copyright © 1992, Wiley Blackwell. All rights reserved