Iran. J. Ichthyol. (June 2016), 3(2): 122–129 Received: April 5, 2015 © 2016 Iranian Society of Ichthyology Accepted: June 1, 2016 P-ISSN: 2383-1561; E-ISSN: 2383-0964 doi: http://www.ijichthyol.org Growth parameters and mortality rate of Neogobius caspius (Eichwald, 1831) in southern part of the Caspian Sea (Teleostei: Gobiidae) Mahmood AGHAJANPOUR1, Sarah HAGHPARAST*2, Hadi RAEISI3, Ahmad Reza JABALE4 1Faculty of Fisheries, Allameh Mohaddes Noori Institute of Higher Education, Mazandaran, Iran. 2Department of Fisheries, Faculty of Animal Science and Fisheries, Sari Agricultural Sciences and Natural Resources University, Mazandaran, Iran. 3Department of Fisheries, Faculty of Agriculture and Natural Resources, Gonbad Kavoos University, Iran. 4Department of Fisheries, Faculty of Fisheries and Environment, Gorgon University of Agricultural Sciences and Natural Resources, Iran. * Email: [email protected] Abstract: In the present work, due to the lack of information on population dynamics of the Caspian goby, Neogobius caspius, we aimed to investigate growth and mortality parameters of this species captured from the south part of the Caspian Sea (Mazandaran Province) during a year from April 2014 until March 2015. Growth and mortality rates were assessed using age calculation. By using least -1 squared method, L∞ and K of the specimens were 16.83 cm and 0.67 year in female specimens and 17.76 cm and 0.83 year-1 in male specimens, respectively. Comparison of the growth curves resulted by likelihood ratio method showed a significant difference between two sexes (P<0.05). The maximum estimated age for female was 4.47 years old while 3.61 years old for male. According to Pauly’s empirical equation, natural mortality rate was calculated 1.25 and 1.41 year-1 for female and male, respectively. Sex ratio (male: female) was 1: 1.14, indicating no significant difference (P>0.05). Based on the results presented here, the present investigation can be regarded as basis for future studies on the Caspian goby. Keywords: Weight-length, Age-length, L∞, Growth parameter, Age-weight. Citation: Aghajanpour, M.; Haghparast, S.; Raeisi, H.; Jabale, A.R. 2016. Growth parameters and mortality rate of Neogobius caspius (Eichwald, 1831) in southern part of the Caspian Sea (Teleostei: Gobiidae). Iranian Journal of Ichthyology 3(2): 122-129. Introduction characters of this unique environment is of great Until now, 63 genera and 199 species according to worth and specific strategies should be performed for Esmaeili et al. (2014) and 63 genera and 122 species their preservation. according to Jouladeh-RoudbarArchive et al. (2015) have ofGobiidae, SIDknown as Gobies, plays an been reported from the Caspian Sea basin that are ecologically important role as predatory fish in an allocated to 18 families, 16 orders and 2 classes, aqueous food chain. Gobies are the largest marine among which two families, Cyprinidae and Gobiidae fish with over 1900 species and inhabit all types of have the most diverse fish species (See Esmaeili et water throughout the world (fresh, marine and al. 2014; Jouladeh-Roudbar et al. 2015). Some of the brackish waters) (Nelson 2006; Freose & Pauly Caspian Sea fish species are exclusively habitant in 2011). The well-represented species of Gobiidae in this region and are not found in other parts of the south part of the Caspian Sea Basin (Iranian waters) world. In addition, near 40% of these fish have are considered as a major food item in the diet of economically many exploitation capabilities. Hence, Acipenseridae species (Holcik 1986; Kiabi et al. conservation of these species implying important 1999; Naderi & Abdoli 2004; Abdoli & Naderi 122 www.SID.ir Aghajanpour et al.-Growth parameters of Neogobius caspius 2008). The prominent species of this family include Considering the lack of investigation on growth duckbill pugolovka (Anatirostrum profundorum parameters, mortality rate, population dynamics and Berg, 1927); Caspian sand goby (Neogobius pallasi stock assessment of the Caspian goby Neogobius Berg, 1916); Caspian bighead goby (Ponticola gorlap caspius, the present work would be beneficial in Iljin, 1949); Caspian stellate tadpole-goby determining the biological aspects of this species in (Benthophilus leobergius Berg, 1949) and Caspian coastal waters of Mazandaran Province, North of Iran goby (Neogobius caspius Eichwald, 1831). The (southern part of the Caspian Sea). genus Neogobius currently consists of 4 species around the world (Froese & Pauly 2013). Although Material and Methods the family Gobiidae has many endemic species, few A total of 101 specimens of the Caspian goby studies have been focused on these species inhabiting (male=54 and female=47) were randomly sampled in the southern part of the Caspian Sea. from southern part of the Caspian Sea. The beach Identification and discrimination of population seines with mesh size 30 and 33 mm was used for in marine fish species contribute with their sampling from April 2014 to March 2015. Biometric population dynamics and corresponding characteristics including length and weight were management policies would be less validated without measured and sexes were determined. Total length population identification. Hence, in studies was measured for estimating growth and mortality pertaining to growth, survival, and reproduction parameters to the nearest millimeter using a digital rates, it is assumed that an independent population ruler. For determination of age composition in each should be investigated (Haddon 2011). The specimen, about 5-6 scales were randomly isolated biological and ecological study of different fish from the forefront of dorsal fin (above the lateral species in an aqueous ecosystem is of primary line), placed in NaOH solution (8%) for one hour and essentials to preserve their stocks. Population then rinsed thoroughly under tap water. Thereafter, dynamic relates to the continually on-time the washed-up scales from each individual were then replacement process of generation and its production fixed by two glass slides and were read under a which is actually referred to the growth and dissecting microscope (using transmitted light) by mortality. The study of growth and mortality two experts to ensure that an agreement in parameters is regarded as a subunit of population interpreting the banding pattern was achieved. The ecology and the main foundation of fish stock Sturges’s formula was used to determine the age biology (Biswas 1993). All the stock assessment class: methods are dealt with age composition data. The R= (Max-Min) +1 estimation of age and growth are the most important K= 1+3.322 log (n) inputs in stock assessment models (Haddon 2011) C= 푅 Archive of SID퐾 which not only indicates the population Where n: the number of samples, K: the number differentiations but also implicates the habitat traits of bins, and C: the class interval. Two-sample (Walter 2005). Kolmogrov-Smirnov test was used to determine Up to now, a few researchers have studied whether size composition of individuals significantly feeding regime and reproductive properties of gobies differed between male and female. (Abbasi et al. 2009; Sarpanah Sarkohi et al. 2010). The length-weight relationship was estimated by But little information has been published in local total length (cm) and total weight (g) according to the journals and no information, even their length and following equation (Mendes et al. 2004; Froese weight, has been recorded by comprehensive fishery 2006): database of Fishbase. 123 www.SID.ir Iran. J. Ichthyol. (June 2016), 3(2): 122-129 b W = αL Where W is weight (g), α: the intercept, L: total length and b: the slope. The L∞ and K were obtained by Gulland & Holt plot (Gulland & Holt 1959) using the following equation: ∆퐿 = 푎 + 푏 ∗ 퐿̅(푡) ∆푡 K = -b L∞ = -a/b Where ∆L/∆t is growth rate as dependent variable and 퐿̅(t) is mean length over the Fig.1. Total length-frequency distribution plot in males corresponding year as an independent variable and females of Neogobius caspius captured from southern part of the Caspian Sea. (Sparre & Venema 1998). Von-Bertallanffy growth 푏 equation given by Sparre & Venema (1998) is as 푊 = 푎퐿 follows: Where W∞ is the asymptotic weight and b: the 퐿푡 = 퐿∞(1 − exp(−퐾)(푡 − 푡0)) slope in length-weight relationship. The following formula was used to estimate W∞: Where L is the average length at age t, L : t ∞ Growth performance index was measured by the asymptotic length and t is the hypothetical age when 0 following equation (Gayanilo & Pauly 1997): the size of fish is zero. The best regression parameters 휙 = log 퐾 + 2푙표푔퐿∞ were obtained by minimizing the errors in residuals The likelihood ratio test was used to compare for finding the optimal values of L∞, k and t0 growth curves between male and female by the (Haddon 2011) as the following: following equation (Haddon 2011): 푆푆푄 = ∑(푋 − 푋 )2 ∑ 푅푆푆 푅푆푆 푂 푒 푋2 = −푁 × 퐿푛 ⌈ 푖⌉ = −푁 × 퐿푛 ( Ω) 퐾 푅푆푆 푅푆푆 푆푆푄 = ∑(푌 − (푎 + 푏푋)2 푃 휔 Where k is the degrees of freedom, N: total Where SSQ is the sum of square; XO: the observed number of observations from both curves combined, value and Xe: the expected value. t0 was calculated RSSΩ: total sum of squared residuals derived from by the Pauly’s equation (Pauly 1980): fitting both curves separately and RSS휔: total sum of log − (푡0) = −0.3922 − 0.2752푙표푔퐿∞ squared residuals derived from fitting curves with − 1.038푙표푔퐾 one of the hypothesized constraints. T is the maximum age (Pauly 1983) and max determined as the following:Archive of SID Results 3 푇 = On the whole, mean total length for female and male 푚푎푥 퐾 The weight-age relationship was fitted by the were measured 9.44±0.774 and 11.57±0.778cm, following equation (Haddon 2011): respectively. The smallest and the largest total length 푏 of the captured fish were 5.1 and 28.5cm, 푤̂ = 푤 [1 − 푒−푘[푡−푡0]] 푡 ∞ respectively.