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Growth Characteristics and Reproduction of Comber, Serranus Cabrilla (Actinopterygii, Perciformes, Serranidae), in the Aegean Sea

The comber, Serranus cabrilla (Linnaeus, 1758), is a moderately exploited commercial serranid species occurring in the Eastern Atlantic and the Mediterranean to a depth of 500 m, on rocks, Posidonia beds, sandy and muddy bottoms (Whitehead et al. 1986). Aegean Sea is an important region for the Turkish fishing industry, accounting for 44 386 t total catch. S. cabrilla is reported to have contributed about 0.18% (in weight) in total catch, which included 64 fish species in the Aegean Sea (Anonymous 2007). In spite of its wide distribution, this species is especially a by catch species for trawls and trammel nets and has a minor commercial value, so that knowledge on the biology of this species is incomplete and scarce when compared by other demersal fish species in the area. Bouain 1981 and Benmouna et al. 1984, who studied comber, focused on the physiology and reproductive biology of the species, ignoring growth and mortality, crucial for stock assessment. Papaconstantinou et al. (1994) reported data on the growth parameters and the length at first maturation for comber in the North Aegean Sea (Greece), while Politou and Papaconstantinou (1995), presented growth parameters and age composition of comber in the Northern Greece. Feeding habits of this species were determined in the Canary Islands by Tuset et al. (1996). Stergiou (1997) and Garcia-Diaz et al. (1997) examined the spawning seasonality and the sex and reproductive aspects in Serranus cabrilla in the English Channel and the Canary Island, respectively. The length–weight relations for comber were presented by Goncalves et al. (1997) and Stergiou and Motopoulos (2001) in south-west coast of Portugal and Greek waters, respectively. Tserpes and Tsimenides (2001) reported data on the age, growth, and mortality of comber from the Cretan shelf. Shape indices to identify regional differences in otolith morphology of comber otoliths were examined by Tuset et al. (2003) from the Atlantic and Mediterranean. From Turkish Seas, Turker-Cakir and Torcu-Koc (2002) examined its feeding habits and also ACTA ICHTHYOLOGICA ET PISCATORIA (2010) 40 (1): 55–60 DOI: 10.3750/AIP2010.40.1.07

LENGTH-WEIGHT RELATIONSHIPS FOR 30 DEMERSAL FISH SPECIES FROM ÇANDARLI BAY (NORTH AEGEAN SEA, TURKEY)

Length-weight relationships were investigated for 30 demersal fish species from Candarlo Bay in the North Aegean Sea. Fish samples were caught from depths of 30-95 m in five different stations by bottom trawl between March 2003 and August 2004. The b v alues in the length-weight relationship va- ried between 1.654 and 3.977, over 50% of which between 2.968 and 3.265 with a mean value of 2.949 (SE = ±0.05). The growth type was deter- mined by t-test: 13 species (43%) showed positive allometries (b > 3; t-test, P 0.05) and the remaning 4 species (14%) negative allometries (b<3; t-test, P < 0.05).

Gut contents and feeding habits of the Great Pipefish, Syngnathus acus Linnaeus, 1758, in İzmir Bay (Aegean Sea, Turkey)

Abstract A total of 112 stomachs of the Great Pipefish, Syngnathus acus Linnaeus, 1758 (56 females and 38 males), was collected in İzmir Bay (Aegean Sea) and analysed in order to determine the feeding habits. 95 specimens (85.6%) were found with prey items in their stomachs. Zooplanktonic organisms were the main food and in terms of numerical (NO%) and frequency (FO%) of occurrence, four main prey categories were determined in the gut content of this species. The most dominant group was found to be harpacticoid copepods (33.6% NO; 57.7% FO), followed by Amphipoda (22.3% NO; 38.2% FO), cypris larvae (12.8%NO; 21.9%FO) and decapod crustaceans (9.5% NO; 16.3% FO), respectively. The numbers of their occurrence indicated that there were significant differences between the seasons. Seasonal differences in the gut content were found in 9 prey groups in spring (p<0.05) and 6 in winter (p<0.05), showing that feeding is more diverse in spring than in winter. Similarly, the number of occurrences indicated that there was a significant difference in the first (p<0.05) and fourth size groups (p<0.05). However, no significant difference was found in the feeding pattern between sexes (p>0.05). Consequently, small crustaceans were the most important prey to be consumed in all seasons by all size groups of Syngnathus acus, whereas decapod crustacean larvae/eggs, larger prey items, were preferred by larger specimens.