Although the red striped mullet is one of the main target fish of the Hellenic demersal fisheries, information about its biology is limited. The aim of this study was to describe the reproductive biology and growth of the species in the south Aegean Sea based on 1032 individuals sampled under the Data Collection Framework Program in 2016. According to the monthly variation of the maturity stages and the gonadosomatic index, spawning activity took place from March to July, although it appeared to occur throughout the year. Length at 50% maturity (L50) was 153.3 and 139.2 mm in females and males, respectively. Individual ages were determined by counting the annuli of otoliths macroscopically. Marginal increment analysis (MIA) combined with complementary information derived from otolith edge analysis, the assessment of the reproductive period and the length–frequency distribution modes of the population showed that annulus formation occurs between February and April. The length–weight relationship revealed a significant sex effect and was described by the parameters α = 0.0155 and b = 2.915 in females, and α = 0.0032 and b = 2.976 in males. The von Bertalanffy growth function (VBGF) parameters for sexes combined were Linf = 346.1 mm, k = 0.299 year−1 and t0 = −0.984 years. Longevity (tmax) was estimated at 11.75 years. This study provides valuable data for the stock assessment of M. surmuletus in one of the major Hellenic fishing grounds located in the south Aegean Sea.

Otolith shape analyses were conducted on three differentspecies of Mullidae (Mullus barbatus barbatus, M.b. ponticus and M. surmuletus). The otolithshape was described by 19 harmonics from elliptic Fourier descriptors. Ina first step, their comparison through canonical discriminant analyses(CDA) was run for all fish with right otoliths, left otoliths andboth otoliths pooled. The latter possibility had a higher discriminatingpower and allowed much more visually explicit results. This impliedthat the two otoliths were not similar as often claimed, and hadeach their specific information. In a second step, the CDA demonstratedstrong spatial discrimination of local populations from variousareas within the Mediterranean basin, i.e. NW Mediterranean, AegeanSea and Black Sea, and between sites within each area. The percentageof well classified individuals of M. barbatus inpredefined groups varied between 78 to 100% depending on sites,and even reached 100% for each site for M. surmuletus.These spatial patterns were most likely linked to differences inenvironmental conditions between areas and sites, such as effectsof strong river runoffs and differences in depths and/or habitattypes. In a third step, CDA also evidenced ontogenetic discriminationsof mullet populations that could be linked (i) to influence of dietof fish of various sizes and (ii) to changes in physiological conditionsaccording to the stage of development of the fish.