Otolith dimensions (length, width), otolith weight and fish length of Sardinella sindensis (Day, 1878), as index for environmental studies, Persian Gulf, Iran

Background Sardines are the most important commercial fishes for Iran. However, information about biology and ecology of sind sardine in Persian Gulf and Oman Sea is scarce. Methods In this study, relationship between fish length and otolith length, -width and -weight of Sardinella sindensis from Bandar Lengeh and Qeshm Island, Persian Gulf were analyzed. In total, 128 and 120 fishes collected from Commercial catches during March 2011- February 2012 in the Bandar Lengeh and Qeshm Island respectively. Results There were no significant differences between left and right otolith (t-test, P > 0.05) or between males and females otoliths (ANCOVA, P > 0.05). For these reasons, only right otoliths were used for next analysis and data of both sexes were pooled. Relationships between fish length and otolith length, width and weight were described by linear regression models and high correlation was shown for all relationships. The highest correlation was between fish length and otolith length (Bandar Lengeh, R 2 = 0.8722; Qeshm Island, R 2 = 0.8661) and relationship between fish length and otolith width showed less correlation than other relationships (Bandar Lengeh, R 2 = 0.7355; Qeshm Island, R 2 = 0.7275). Conclusions The result from this study shows that fish length and otolith growth have a positive relationship, so can be a useful tool to evaluate the growth of fish and fish stocks and finally fisheries management.