J Appl Ichthyol. 2017;1–5. wileyonlinelibrary.com/journal/jai | 1 © 2017 Blackwell Verlag GmbH Received: 12 May 2016 | Accepted: 17 February 2017 DOI: 10.1111/jai.13404 ORIGINAL ARTICLE The relationship between otolith size and estimated age of tigertooth croaker (Otolithes ruber Bloch and Schneider, 1801) in Oman Sea, Iran B. Rahnama 1 | E. Kamrani 2 | F. Radfar 3 | R. Yadollahvandmiandoab 4 | M. Parsa 1 1 Young Researchers and Elite Club, Bandar Abbas Branch, Islamic Azad University, Bandar Abbas, Iran 2 Department of Marine Sciences and Technologies, Hormozgan University, Bandar Abbas, Iran 3 Young Researchers and Elite Club, Borojerd Branch, Islamic Azad University, Borojerd, Iran 4 Programa de Pós-graduação em Ciências Biológicas (Zoologia), Departamento de Sistemática e Ecologia – DSE, Centro de Ciências Exatas e da Natureza – CCEN, Universidade Federal da Paraíba – UFPB, Cidade Universitária, João Pessoa, PB, Brazil Correspondence Reza Yadollahvandmiandoab, Programa de Pós-graduação em Ciências Biológicas (Zoologia), Departamento de Sistemática e Ecologia – DSE, Centro de Ciências Exatas e da Natureza – CCEN, Universidade Federal da Paraíba – UFPB, Cidade Universitária, João Pessoa, PB, Brazil. Email: rezayadollahvand.tmu@gmail.com Summary The relationships between somatic growth and otolith dimensions, otolith size to esti- mated age and growth parameters of the tigertooth croaker (Otolithes ruber) were in- vestigated in 100 specimens (size range: 19.1–52.0 cm, total length) from the Oman Sea area, September 2014. All 100 otoliths were sectioned and determined by age. The oldest specimen was a 4.5-year-old female with a total length of 40.6 cm; the youngest specimen was also a female estimated at 1 year of age with a total length of 19.1 cm. The von Bertalanffy growth equation was estimated as L t = 54.70 (1 − exp (−0.37 (t + 0.21))). Concluded was that there is a significant relationship between body size, otolith dimensions and estimated age of Otolithes ruber. 1 | INTRODUCTION Tigertooth croaker (Otolithes ruber; Sciaenidae) is a demersal species distributed in tropical, subtropical and temperate seas, including the Persian Gulf and Oman Sea, Indian and Pacific Oceans, China and the Malayan archipelago (Brash & Fennessy, 2005). Otolithes ruber is fished along the four Iranian coastal provinces of Sistan-Baluchestan, Hormozgan, Bushehr and Khuzestan. Fishing gear used are pots, gillnets, hooks, lines and trawls. Knowing the age of a fish provides a clue as to its longevity, age at first maturity, age of recruitment and growth. Therefore, accurate ageing of fish is critical to understanding its population dynamics (Gaamour & Khemiri, 2004; Li, Chen, He, & Chen, 2009). Several approaches to determine age and growth have been used, such as length–frequency analyses, tagging and recapture experi- ments and analysing marks on scales, otoliths, spines and vertebrae (Stequert, Panfili, & Dean, 1996), whereby otoliths are the preferred structures (Gaamour & Khemiri, 2004; Metin & Ilkyaz, 2008). The size and shape of otoliths vary considerably among species (Rodríguez Mendoza, 2006). Theoretically, a pair of otolith annual rings is formed each year: an opaque summer ring and a hyaline winter ring. The opaque ring is formed during the growth season and is broader than the hyaline ring formed during the winter, when growth is slower. Age of fish is usually determined by counting the hyaline rings (Hassager, 1991). Any major change in the environment in which a fish lives is likely to produce a ring. In temperate regions, differences between summer and winter are marked by both changes in water temperature and the amount of food available. Daily growth increments have also been detected on some fish otoliths (Rodríguez Mendoza, 2006). Earlier studies on O. ruber from the region have focused on feed- ing habits (Bandani, Kiyabi & Akrami, 2007) and stock assessment (Mohammadkhani & Yelghi, 2010). However, Eskandari, Savari, Kochanian, and Taghavi Motlagh (2012) studied age and growth of O. ruber in the northwestern area of the Persian Gulf based on otolith cross sections. Despite its importance in waters of the Oman Sea, no