Target strength measurements of European Anchovy (Engraulis encrasicolus L.) by the control method

European anchovy, Engraulis encrasicolus (L.) is an important commercial species on the Atlantic coasts northward to southern North Sea, Mediterranean, Black Sea and also Aegean Sea. Target strength (TS) is a scale factor to get abundance, but there is few TS information in terms of this kind of species. In this study we measured TS of European anchovy by the control method in the fresh water tank. The measuring system's frequency is 38 kHz. Samples were captured in the Aegean Sea and transported with ice by air kept in the refrigerator under -40 degree in the laboratory. After defrosted TS patterns of 12 European anchovy were measured by the control method. Target strength patterns were measured as a function of tilt angle, ranging from -50 degrees (head down aspect) to 50 degrees (head up aspect) at every 1 degree. Obtained TS pattern become broad. Normalized maximum TS become -66.5 dB. Normalized average TS become -69.8 dB and -72.2 dB assuming tilt angle distribution as N(-3.4, 10.3) and N(12.0, 23.5)

The use of otolith length and weight measurements in ageestimations of three Gobiidae species (Deltentosteus quadrimaculatus, Gobius niger, and Lesueurigobius friesii) [Üç gobiidae türünün otolit boyu ve agi{dotless}rli{dotless}gi{dotless}ni{dotless}n yaş tahmininde kullani{dotless}mi{dotless} (Deltentosteus quadrimaculatus, Gobius niger ve Lesueurigobius friesii]

Ageestimations were made using otolith length and weight measurements from 3 goby species in the central Aegean Sea: the four-spotted goby (Deltentosteus quadrimaculatus Valenciennes, 1837), the black goby (Gobius niger Linnaeus, 1758), and Fries's goby (Lesueurigobius friesii Malm, 1874). A total of 266 individual four-spotted gobies, 283 black gobies, and 124 Fries's gobies provided otolith samples for analysis. The relationships between fish age and otolith length and fish age and otolith weight were determined, as were the relationships between total length and otolith length and total length and otolith weight. Results indicated that the relationship between fish age and otolith weight was the most suitable forestimating the age of the studied species. The relationships wereestimated at t = 0.338W - 0.199 for the four-spotted goby, t = 0.147W - 0.085 for the black goby, and t = 0.400W - 0.619 for Fries's goby. The present paper also provides drawings of the species' otoliths to aid in the identification of the species. Th is research provides information that can be applied not only for ageestimation but also for prey identification andestimation of the size of prey ingested by piscivorous predators. © TÜBİTAK

Age, growth and reproduction of four-spotted goby, Deltentosteus quadrimaculatus (Valenciennes, 1837), in Izmir Bay (central Aegean Sea) [İzmir Körfezi (Orta Ege Denizi) dört benekli kayabali{dotless}gi{dotless}'ni{dotless}n, Deltentosteus quadrimaculatus (Valenciennes, 1837), yaş, büyüme ve üreme özellikleri]

Length distribution, sex ratio, length-weight relationship, age, growth, spawning period, age, and length at first maturity of four-spotted goby inhabiting İzmir Bay were investigated. A total of 1696 four-spotted goby were collected by trawl hauls between July 2004 and June 2007. The size of the fish sampled ranged from 3.1 to 9.2 cm total length. The samples were composed of 31.1% females, 27.7% males, and 41.2% juvenile individuals, with a female to male ratio of 1:0.89. The age of the fish ranged from 1 to 5 years. The length-weight relationship and the von Bertalanff y growth function were estimated for all individuals as: W = 0.0036L 3.45 and L t = 10.29[1 - e -0.371(t + 0.502)]. Spawning period started in February and continued until May. The lengths at first maturity of females and males were 6.15 ± 0.18 and 6.38 ± 0.20 cm total length, respectively. © TÜBİTAK

Growth and reproduction of blotched picarel (Spicara maena Linnaeus, 1758) in the central Aegean Sea, Turkey [Orta Ege Denizi izmarit bali{dotless}gi{dotless}'ni{dotless}n (Spicara maena Linnaeus, 1758) büyüme ve üreme özellikleri]

Growth and reproduction of the blotched picarel, Spicara maena (Linnaeus, 1758), were determined based on specimens (n = 2547) collected from the central Aegean Sea between July 2004 and June 2007. The samples consisted of 71.9% females, 16.2% males, and 11.9% immature individuals. The sex ratio of females to males was 1:0.23. The lengthweight relationship was W = 0.011L3.02, W = 0.011L3.00, and W = 0.011L2.99 for the combined sexes, females, and males, respectively. For all samples and both sexes the length-weight relationship showed isometric growth. The von Bertalanffy growth equation was fitted on the basis of mean length-at-age data, resulting in parameter values of L? = 21.99 cm, k = 0.255 year-1, and to = -1.165 year, and weight at infinity (W?) was calculated as 123.35 g. Length at first maturity was 8.1 cm in males and 8.5 cm in females. On the other hand, first reproduction length was 11.51 cm and 13.12 cm for females and males, respectively, both corresponding to 2 years of age. It was observed that spawning occurred between March and June. © TÜBİTAK

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. © 2017, Scientific Society of Szczecin. All rights reserved.103Y132 National Council for Scientific Research L/003This study was carried out with financial support from the Scientific and Technological Research Council of Turkey (TUBITAK), project 103Y132, and Ege University Science and Technology Center (EB?LTEM), project 2005/B?L/003. -

Biological characteristics of the common pandora, Pagellus erythrinus (Linnaeus, 1758), in the central Aegean Sea [Orta ege Denizi ki{dotless}rma mercan bali{dotless}gi{dotless}'ni{dotless}n (Pagellus erythrinus (Linnaeus, 1758)) biyolojik özellikleri]

Abstract: We investigated the length distribution, sex ratio, sex inversion length, length-weight relationship, age, growth, spawning period, age and length at first maturity of the common pandora inhabiting İzmir Bay. A total of 2654 common pandora were collected by trawl hauls of İzmir Bay (Turkey) between January 2002 and June 2007. The size of the samples ranged from 4.1 cm (0.95 g, February) to 27.8 cm (207.30 g, April) in total length. The samples were composed of 64.7% females, 5.1% males, 0.3% hermaphrodites, and 29.9% immature individuals, with a female to male ratio of 1:0.08. The age composition of the samples ranged between 1 and 10 years. The length-weight relationship and the von Bertalanff y growth function were estimated for all individuals as: W = 0.0143L2.95 and Lt = 30.673[1 - e-0.165(t - (-0.857))]. The spawning period started in June and continued until October. The total lengths at first maturity of females and males were 11.30 and 15.08 cm, respectively. © TÜBİTAK