İlkyaz A.T., Metin G., Soykan O., Kınacıgil H.T. 2017. Age, growth, and reproduction of Mediterranean scaldfish, Arnoglossus laterna (Actinopterygii: Pleuronectiformes: Bothidae), in the east-central Aegean Sea. Acta Ichthyol. Piscat. 47 (1): 53–61.
In Turkey, the Mediterranean scaldfish, Arnoglossus laterna (Walbaum, 1792), is a discard fish species and it has a ‘least concern’ status on the IUCN Red List which indicates a low extinction risk. Although there are some studies investigating biology of this species, the knowledge of the mortality rates, spawning period, first maturity size, and age are not available for the study area. This paper, for the first time, provides some data on unknown population parameters for the east-central Aegean Sea. The aim of the presently reported study was to expand our knowledge on the biology of A. laterna.
Materials and methods.
Specimens of A. laterna were collected at monthly intervals by bottom trawl hauls between July 2004 and June 2007 from İzmir Bay (Turkey). The total length (L, cm), total weight (W, g), gonad weight (WG, g), and the sex were determined and the sagittal otolith pairs were removed for age reading. The length–weight relations were estimated by linear regression analysis on log-transformed data by equation: W = aLb. The growth was analysed by fitting the VBGF to size-at-age data using standard nonlinear optimization methods. Spawning period was established with monthly variations of the GSI values. Length at first maturity was estimating by the logit function.
A total of 2469 A. laterna individuals were sampled and the sex ratio was calculated as 1 ÷ 1.57 (F ÷ M). The length range of the sample was from 4.4 to 19.8 cm and the mean length was calculated as 9.4 ± 0.05 cm. For all samples, the length–weight relation was (W = 0.0074L3.04) and the growth type was determined as positive allometric. The age distribution of individuals varied from the ages of 1 to 8 years and the growth equation was determined as Lt = 20.62[1 – e–0.245(t + 1.071)]. The first maturity lengths were estimated as 11.88 cm for females and 11.41 cm for males.
The presently reported study provides the age, growth, and reproduction parameters for A. laterna and the first information on the mortality rates, spawning period, first maturity size, and age parameters for the east-central Aegean Sea. These parameters can be useful for managers in the management and conservation of the stock.
length distribution, sex ratio, length–weight relation, spawning season, mortality rate, size at first maturity