Int. J. Aquat. Biol. (2019) 7(4): 218-223 ISSN: 2322-5270; P-ISSN: 2383-0956 Journal homepage: www.ij-aquaticbiology.com © 2019 Iranian Society of Ichthyology Original Article Some biological properties of Kura goby, Ponticola cyrius (Kessler, 1874) (Gobiiformes, Gobiidae) from Kura River, Turkey Erdoğan Çiçek*1, Selda Öztürk1, Sevil Sungur2 1Department of Biology, Faculty of Art and Sciences, Nevşehir Hacı Bektaş Veli University, Nevşehir, Turkey. 2Health Services Vocational School, Nevşehir Hacı Bektaş Veli University, 50300, Nevşehir, Turkey. s Article history: Received 7 June 2019 Accepted 21 August 2019 Available online 2 5 August 2019 Keywords: Growth parameters Ardahan Çot Creek Caspian Sea Abstract: This work presents some biological properties, including length-frequency, length-weight relationships, Fulton’s condition factor, growth parameter, and growth performance and mortality indices of Kura goby, Ponticola cyrius. A total of 73 specimens were collected from the Çot Creek a tributary of Kura River, from May to September 2015. Age of P. cyrius varied from 0 to III age with age group I as the most frequent (56.16%). The total length and weight ranged 4.3-16.4 cm, and 1.10- 50.10 g, respectively. The length-weight relationship was W=0.0145L2.9795 with b-value indicating isometric growth pattern. The estimated von Bertalanffy growth parameters are L = 26.36 cm, k = 0.187 year-1 and to = -1.33 year. Growth performance index (Φ') and mean Fulton’s condition factor were estimated as 2.115 and 1.43, respectively. Instantaneous rate of total, natural and fishing mortalities were 0.588, 0.371 and 0.217 year-1, respectively and the exploitation rate was calculated as 0.369. Introduction The genus Ponticola Iljin, 1927 consists 14 valid species inhabiting the Black and Caspian Sea basins (van der Laan, 2019) that 8 of them viz. P. constructor, P. cyrius, P. eurycephalus, P. kessleri, P. rattan, P. rizensis, P. syrman and P. turani are found in Turkey (Çiçek et al., 2015). Among them, Kura goby, P. cyrius (Kessler, 1874) is endemic to the Kura River drainage (Kuru, 1975; Çiçek et al., 2016) and its absence in the lower Kura River could have been prevented by prior penetration of P. gorlap (Vasil'eva and Vasilev, 1995). The Kura goby prefers slow current and muddy bottoms. This species reaches a maximum total length of about 13.0 cm (Coad, 2019). Few population dynamic parameters of the Kura goby have been provided by Zamani Faradonbeh et al. (2015) and Asadi et al. (2017) from the southern Caspian Sea basin. Recently Vasileva et al. (2015) described P. iranicus from of Sefid river drainage including Shahre Bijar, Totkabon and Gisum rivers, Guilan Province which probably is those previously reported *Correspondence: Erdoğan Çiçek DOI: https://doi.org/10.22034/ijab.v7i4.706 E-mail: erdogancicek@nevsehir.edu.tr P. cyrius in Iranian part of the Caspian Sea basin, that need to be confirmed (Nikmehr et al., 2018, 2019). The growth is the determination of the body size as a function of age and the stock assessment methods work essentially with age composition data (Sparre and Venema, 1998; Hawk and Allen, 2014). Hence, age and growth information are crucial for management of the exploited fish stocks, and in this regard, the determination of the biological characteristics of a species is of great importance. Therefore, this study aimed to provide some population parameters of P. cyrius inhabiting Kura River part of Turkey. Materials and Methods A total of 73 specimens were collected from the Çot Creek (41.17566121N, 42.94917989E), a tributary of the Kura River, eastern Anatolia Region, Turkey using an electrofishing device in May-September 2015 (Fig. 1). The specimens were collected in slow flowing creek over rock-stony and muddy substrates. During sampling, stream width was 16 m, mean water depth 219 Int. J. Aquat. Biol. (2019) 7(4): 218-223 24 cm, water temperature 21°C and flow rate of 0.67 m/s. The specimens were fixed into 10% formalin, after anesthesia, transferred to the laboratory and then stored in 70% ethanol. Measurements were taken using a digital calipers and data recorded to the nearest 0.1 mm. Meristic characteristics were counted using a stereo- microscope. The taxonomic key given by Berg (1949), Kuru (1975) and Coad (2018) were used to identify the samples. The total length and total weight were measured and weighed to the nearest 1 mm and 0.01 g, respectively. The scale samples were removed from the nape area (cycloid) and the left side of the body ventral to the dorsal fin (cteniod) for the age determination. Scales were soaked in water and examined independently twice with no reference to the previous readings and without any knowledge of the length or weight of the fish under the stereomicroscope. The precision was measured by the percentage of agreement between the two readings (Chang, 1982). The assessment of age was based on the determination of the number of annuli on each scale. The length-frequency data were plotted with 1 cm length intervals. The length-weight relationships were determined according to the equation of W = a*Lb, (Sparre and Venema, 1998), where W is total weight, a and b are regression constants and L is total length. Growth in length and weight were expressed in terms of the von Bertalanffy equation of Lt = L1-e-k(t-to). The growth parameters L, k and to were estimated using the least squares method (Sparre and Venema, 1998). Correspondence between empirical data and an expected distribution was tested by Khi2 test. The b value was tested by t-test to verify that it was significantly different from the isometric growth (b = 3). The growth performance index (Φ') was calculated Figure 1. General body shape of Ponticola cyrius. (A) Pelvic disc fraenum with angular lobes, and (B) ctenoid and (C) cycloid scales. 220 Çiçek et al./ Biological properties of Kura goby using the formula (Pauly and Munro 1984) of Φ' = logk+2logL∞ and Fulton’s condition factor (K) by equations of 𝐾 = 100 𝑊 𝐿𝑏 where; W = total weight, L = total length and b = regression constant (Sparre and Venema, 1998). The instantaneous rate of total mortality coefficient Z was estimated using Beverton and Holt (1956)’s Z Equation using the formula of 𝑍 = 𝑘 (𝐿∞−�̅�) (�̅�−𝐿′) , where �̅� is the mean length of the entire catch, and L' = the lower limit of corresponding length intervals (Sparre and Venema, 1998). The natural mortality coefficient (M) was estimated following Pauly’s empirical formula (Pauly, 1980), linking the natural mortality with the von Bertalanffy parameters, L∞ (cm), k and mean annual temperature (T, °C) of water in habitat (in this case 9.3°C. Log10M = -0.0152 - 0.279log10L∞ + 0.6543Log10k + 0.463Log10T. Fishing mortality rate (F) was calculated as the difference between Z and M (Z = F+M). The value of the average annual exploitation rate (E) was obtained by E=F/Z (Sparre and Venema, 1998). Results and Discussions Age and growth: Age was determined by comparing the growth increment readings on scales by two readers. It was observed that the number of annuli counted for each specimen was similar for the two readers and there was a high harmony (89.05%) between the age estimations. Age of P. cyrius varied from 0 to III age groups and group I was the most frequent groups containing 56.16%, whereas the age group III was the least i.e. 2.74%. Indeed, life span of this species reported up to 3 years (Coad, 2018). The total length ranged 4.3-16.4 cm with a mean (±SD) of 9.63±2.08 cm. In the previous studies, range of total length reported as 4.9-11.0 cm (8.1±2.1) by Table 1. Age, length and weight-frequency distribution of Ponticola cyrius from Kura River drainage. Age n %n Mean Length (cm) Range Growth Rate % Mean Weight (g) Range 0 9 12.33 5.54±0.91 4.3-7.3 2.50±1.28 1.10-5.34 I 41 56.16 9.45±0.82 8.2-11.6 70.56 12.12±3.26 7.48-19.41 II 21 28.77 11.25±0.81 9.7-12.7 19.05 20.05±4.73 11.48-30.91 III 2 2.73 14.75±2.33 13.1-16.4 31.11 39.31±15.27 28.51-50.10 Overall 73 9.63±2.08 4.3-16.4 13.96±7.91 1.10-50.10 Figure 2. Length distribution of Ponticola cyrius from Kura River drainage. 221 Int. J. Aquat. Biol. (2019) 7(4): 218-223 Zamani Faradonbeh et al. (2015) and 2.3-11.9 cm (7.5±2.4) by Asadi et al. (2017). The longest observed specimen in this study was 16.4 cm. Total weight varied between 1.10-50.10 g with a mean of 13.96±7.91 g. Based on the results, P. cyrius grows rapidly in their first year, and then this rate declines (Table 1). According to Vasil'eva and Vasil'ev (2003) maturity of P. cyrius is attained in the second or third year. Based on our examination, II year’s old specimens had eggs. The total length-frequency distribution of Kura goby is given in Figure 2. The distribution was unimodal and the highest frequency (27.4%) was observed in the 10 cm length class followed by the 9 cm length class (26.0%). Length-weight relationship: The length-weight relationship for P. cyrius is presented in Figure 3. The correlation (r2) for regression analysis indicated strong relationship between the variables. The total length- weight relationship was as W=0.0145L2.9795 with the b-value was not significantly different from 3.0 (P<0.001) indicating isometric growth of P. gorlap. In the previous studies, length-weight relationships of Ponticola c.f. cyrius were reported as W=0.00001*L2.938 and W=0.0006*L3.214 by Asadi et al. (2017) and Zamani Faradonbeh et al. (2015), recpectively. However, the confidance intervals of the b-value were not estimated in both of these studies. The length-weight relationship may be influenced by sex, maturity, geographical location and environmental conditions given year (Balon, 1984). The von Bertalanffy growth parameters estimated as follows L = 26.36 cm, k= 0.187 year-1 and to = - 1.33 year (Table 2). Growth performance index (Φ') and mean Fulton’s condition factor were estimated 2.115 and 1.43, respectively. The back-calculated lengths were determined using von Bertalanffy growth parameters and the observed and calculated growth in total length is presented in Figure 4. The growth curves were not significantly different between the observed and calculated length (P<0.05). Mortality: Instantaneous total (Z), natural (M) and Table 1. Length-weight relationship and von Bertalanffy estimated growth parameters for Ponticola cyrius from Kura River drainage. b 95% CI of b a r2 L∞ (cm) K (year-1) L∞ (g) t0 (year) Φ' K Type of growth Author 2.9795 2.919-3.041 0.0145 0.993 26.36 0.187 248.20 -1.33 2.115 1.43 I This study 2.938 0.00001 0.983 1.11 -A Asadi et al. (2017) 3.214 0.0006 0.861 +A Zamani Faradonbeh et al. (2015) Figure 3. Length-weight relationship for Ponticola cyrius from Kura River drainage. 222 Çiçek et al./ Biological properties of Kura goby fishing (F) mortalities were estimated as 0.588, 0.371 and 0.217 year-1, respectively. The exploitation rate (E) was calculated as 0.369 using estimated mortality rates. There is no published estimation of the natural and total mortality for P. cyrius for comparison. Instantaneous natural mortality was estimated higher than fishing mortality. The species is fished only as by-catch, since has no commercial value. 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