Hotos G.N., Katselis G.N. 2011. Age and growth of the golden grey mullet Liza aurata (Actinopterygii: Mugiliformes: Mugilidae), in the Messolonghi-Etoliko Lagoon and the adjacent Gulf of Patraikos, Western Greece. Acta Ichthyol. Piscat. 41 (3): 147–157.
The fisheries of the Greek lagoons is based on the seasonal fish migration from coastal areas to the lagoon and the summer-to-winter offshore fish migration. The knowledge of the age and growth of the species in the two connected regions is essential for the proper management of the resources. The aim of this study was to estimate the age and growth of Liza aurata in the Messolonghi-Etoliko Lagoon system and the neighbouring coastal waters of the Gulf of Patraikos (Western Greece).
Materials and methods.
From December 1992 to February 1994, a total of 1146 individuals of Liza aurata were caught in the Klisova Lagoon (part of the lagoon complex of Messolonghi-Etoliko) and their adjacent sea coastal area, using barrier fish traps, seine, and trammel nets. The fish age was determined from scale readings. Back calculated lengths at age, as derived using scales readings, were used to estimate the growth parameters of von Bertalanffy equation. The length–weight relation was estimated by the equation: W = a · Lb.
The total length (L) of examined specimens ranged from 9.7 to 59 cm. The scale readings revealed nine age classes in the Gulf of Patraikos (0 to VIII) and seven (0 to VI) in the lagoon. Maximum age was found to be 8 and 6 years for females and males, respectively. The analysis of the residuals sum of squares showed that the VBGF curves of sexes between the Patraikos sea area and the lagoon were not significantly different (sexes: F = 0.51, P > 0.05 and regions: F = 0.46, P > 0.05, respectively). The estimated values of VBGF for all samples were L¥ = 65.08 ± 2.61 cm; k = 0.149 ± 0.017 year–1 and to = –1.15 ± 0.063 year. No significant difference on the length–weight relations among the sexes was found (F = 3.15, P > 0.05) while a significant difference on the length–weight relations among the regions (sea: W = 0.0036L3.26; lagoon: W = 0.0057L3.13) was found (F = 21.1, P < 0.05) which reproduced a rather low difference (<±5%) along the size (weight) of species. The length–weight relations exhibited allometry.
The age and growth in length and weight of Liza aurata in the lagoon system of Messolonghi-Etoliko and the neighbouring seawaters of Gulf of Patraikos were not significantly different. This could be explained by the fact that the relative high salinity situation of the lagoon may rebut their high trophic advantage for the fish and/or alternatively, by a scenario that is based on the seasonal migrations of species between sea and lagoon.
Golden grey mullet, Liza aurata, age, growth, western Greece, von Bertalnaffy estimates