Ozan Soykan

A preliminary study on the survival of brown comber, Serranus hepatus (Actinopterygii, Perciformes, Serranidae), escaping from the codend of a bottom trawl

Demersal trawling in Turkish Coasts is performed on the grounds where more than 50 species encounter the gear (Tosunoglu et al. 2003b). Similarly, it has been reported that trawl fisheries is generally multispecies in the Mediterranean Sea (Tudela 2004). A considerable amount of fishes such as annular seabream, (Diplodus annularis) (see Ozbilgin et al. 2005), black goby (Gobius niger), red bandfish (Cepola macrophthalma) (see Lamprakis et al. 2003) end up as discard or bycatch in the bottom trawl fishery that targets the marketable demersal species. One of the reported discard fishes captured by bottom trawls (Lamprakis et al. 2003) is brown comber, Serranus hepatus, which is a species of a minor commercial (Froese and Pauly 2009). Minimum landing size (MLS), which is designed to allow escapement of undersized fish, for this species is not specified in the Turkish Fisheries Regulations (Anonymous 2008). Discard of trawl fisheries are commonly a result of conventional diamond mesh cod-ends regarding MLS of the target species (Graham and Kynoch 2001). In Turkish waters, large amount of bycatch and discard where reported by Tosunoglu et al. (2003b) and Metin et al. (2005). According to the present legislation, minimum trawl codend mesh sizes are 40 mm for the Black Sea and 44 mm for the Aegean Sea and the Mediterranean Sea (Anonymous 2008). The fate of fish such as brown comber, in terms of unaccounted fishing mortality, is ACTA ICHTHYOLOGICA ET PISCATORIA (2010) 40 (1): 27–36 DOI: 10.3750/AIP2010.40.1.04

First record of pignosed arrowtooth eel, Dysomma brevirostre (Actinopterygii: Anguilliformes: Synaphobranchidae), from the Aegean Sea

In 2008, a specimen of a pignosed arrowtooth eel, Dysomma brevirostre (Facciola, 1887), was caught by a bottom trawling operation at Sigacik Bay (Aegean Sea), Turkey. Total length (TL) and weight of the fish were 23.2 cm and 2.00 g, respectively. This study reports the first record of D. brevirostre from the Aegean Sea and logs a new species for the Turkish Ichthyofauna.

Age, growth, and reproduction of Mediterranean scaldfish, Arnoglossus laterna (Actinopterygii: Pleuronectiformes: Bothidae), in the east-central Aegean Sea

Background. 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. Results. 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 growt type was deterined as positive allometic. The age distribution of individuals varied from 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. Conclusion. 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.