Otolithometry and scalimetry—two valid methods to describe the growth of peacock wrasse, Symphodus tinca (Actinopterygii: Perciformes: Labridae) from eastern Algeria

Background. The peacock wrasse, Symphodus tinca (Linnaeus, 1758), is a common Mediterranean fish and the most abundant labrid species on the eastern coast of Algeria. Its age and growth, however, have been poorly studied. Such data are essential for proper fisheries management. The aim of this study is to provide information on the age and growth of this wrasse species from the eastern Algeria based on two different methods of fish age determination. Materials and methods. Age and growth of Symphodus tinca were determined by examining otoliths and scales of the fish sampled between January and December 2011 on the eastern coast of Algeria. Otoliths and scales from 515 and 469 specimens, respectively, were used to determine the age using commonly accepted procedures. Results. The age was successfully determined in 513 (99.61%) otoliths (277 females, 209 males) and in 428 (91.25%) scales (232 females, 173 males), representing age classes between 0+ and 5+ years (1+–3+ years for females and 1+–5+ years for males). The validity of the otolith and scale readings for estimating age and growth was supported by the back-calculation method. The success rate in reading otoliths and scales of Symphodus tinca was very high. The growth pattern is well described by the von Bertalanffy growth equation: from otoliths, L∞ = 26.46 cm, k = 0.79, t0 = –0.12 for females and L∞ = 32.32 cm, k = 0.54, t0 = –0.22 for males; from scales, L∞ = 26.61 cm, k = 0.61, t0 = –0.45 for females and L∞ = 32.50 cm, k = 0.48, t0 = –0.31 for males. Otolithometry and scalimetry gave very close results. The total lengths (TL) ranged from 4.9 to 31.3 cm, and eviscerated weight (We) from 1.38 to 400.65 g. The length–weight relation showed an isometric growth for females (b = 3.01), and negative allometric growth for males (b = 2.86). Conclusion. The age was estimated by otolith and scale reading for males and females where the two methods yielded the similar results. Although the otolith readings presented a better fit (99.61%), scales could also be used with fairly good results (91.25%). In the future, research on the growth of S. tinca either of these two methods can be used to save time. The scale method, however, is certainly the easiest