Validation of daily increments deposition in the otoliths of European anchovy larvae ( Engraulis encrasicolus L.) reared under different temperature conditions

Abstract

European anchovy eggs ( Engraulis encrasicolus L.) were hatched and larvae reared in the laboratory in order to validate the daily increment deposition in otoliths under different temperature condition. Additionally, the effect of temperature on otolith and larval growth and on the fish length and otolith radius relationship was also analysed. On sagittae, one to four increments can be depositioned during the embryonic stage and the first regular increment was formed the day after hatching. Temperature was found to have a significant effect on the increment deposition rate and otolith growth. A daily increment deposition rate was confirmed in larvae reared under conditions of higher temperatures (20.8 and 22.3 °C), while the apparent rate of increment formation of larvae reared at 17.6 °C was clearly lower. Standard length and otolith radius were closely related and this relationship was affected by both temperature and growth rates. The implications of the effect of these variables on otolith growth are further analysed in relation to non-daily pattern of increment deposition found at the lowest temperatures.