Panfili Jacques auteur aut IRD Tomas J. auteur aut IRD text journalArticle eng text/pdf born digital access Two tilapia species, Saro- therodon melanotheron (brackishwater fish) and Oreochromis niloticus (fresh-water fish), were marked with tetracy-cline and reared in Côte d'Ivoire (West Africa) in intensive (fish fed) and extensive (fish unfed) conditions. Juvenile and adult otoliths of the two species were examined. They were cut into transverse thin sections (10 to 40 ?m), and otolith microincrements were counted on the sulcus along the ventral axis. Results for both species showed that microincrements are laid down daily. The number of days of growth reflects the number of microincrements (regression with slope not different from 1 and intercept not different from 0; P>0.05). This technique has a tendency to underestimate age ( P<0.05): for S. melanotheron, the mean bias error is 4.4 d for juveniles (48 to 169 d of growth) and 8.1 d for adults (34 to 185 d of growth); for O. niloticus, the mean bias error is 0.9 d for juveniles (31 to 62 d of growth) and 5.1 d for adults (36 to 65 d of growth). Back-calculation of individual length at marking is very sensitive to an uncoupling between otolith and fish-specific growth rates. With the present data, back-calculated lengths overestimated actual size. When otolith and fish growth were coupled, length was back-calculated accurately. specialized COTE D'IVOIRE 034BIOVER01 040AQUAC 99 1 139-150 2001 0090-0656 https://www.documentation.ird.fr/hor/fdi:010085041 0090-0656 [F B010085041] https://www.documentation.ird.fr/hor/fdi:010085041 https://www.documentation.ird.fr/intranet/publi/2023-06/010085041.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2022-05-30 2023-06-20 fdi:010085041 fre