This study aims to investigate some biological characteristics of Atlantic bonito, Sarda sarda Bloch, 1793, from the Turkish coasts of the Black Sea and the Sea of Marmara. A total of 212 S. sarda (100 females, 89 males, and 23 undetermined) were sampled monthly between May 2011 and September 2012. The sex ratio (♂/♀) was 0.89; females prevailed but not statistically significantly so. Fork lengths of all sampled individuals ranged from 17.7 to 63.0 cm. The length-weight relationship for all individuals was calculated as W = 0.01 L 3.085 . The ages of the fish ranged from 0+ to 2+. Growth parameters calculated according to the von Bertalanffy growth equation were L∞ = 69.565 cm, k = 0.439, t 0 = -1.327 for females; L∞ = 74.603 cm, k = 0.364, t 0 = -1.518 for males; and L∞ = 67.883 cm, k = 0.463, t 0 = -1.220 for both sexes. One hundred ovaries were obtained from the females, and these ovaries were histologically examined to determine the reproductive conditions and developmental stages of oocytes. The gonadosomatic index values calculated for females indicated that spawning generally occurred between May and August. The most intensive spawning period was observed in June and July. The length at first maturity was estimated to be 42.5 cm for females and 36.8 cm for males.

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The study aims to identify the age and growth parameters of bullet tuna (Auxis rochei) in Turkish waters. The fish were caught from the Turkish Mediterranean coasts between December 2008 and December 2009. A total of 186 dorsal fin spines obtained from the specimens were analyzed for ageing and growth studies. The fork length of the aged individuals ranged from 34 to 48 cm for males and from 35 to 46.5 cm for the females. Fish ages ranged 1 to 5 years old and the mean lengths by age were calculated for both sexes. Growth parameter estimates were calculated from 150 cut spine sections which provided readable growth annuli by sex. The growth parameters based on standard von bertalanffy growth function are the following: for males, L∞ (asymptotic length) is equal to 60.417 cm; k (growth coefficient) is equal to 0.159; t 0 (age at zero length) is equal to − 4.311; for females, L∞ is equal to 49.238 cm; k is equal to 0.312; t 0 is equal to −3.011; for both sexes, L∞ is equal to 57.388 cm; k is equal to 0.181and t 0 is equal to −4.155, respectively. The length and weight relationship was calculated with W equal to 0.0542 L 2.68 .

The fish species Symphodus bailloni (Valenciennes, 1839) reported in the present study were collected between June 2010 and June 2011 from the western Black Sea coasts which were previously not recorded from the Black Sea coast of Turkey. A total of 717 specimens of S. bailloni were measured, ranging between 8.9 and 15.4 cm TL. Morphometrics, meristics, and diagnostic characteristics of the species are presented.