Iranian Journal of Fisheries Sciences 17(2) 357-368 2018 DOI: 10.22092/IJFS.2018.115499

Population dynamics of Carasobarbus luteus in Shadegan International Wetland, Iran

Ghorbani R.1*; Hedayati A.1; Hashemi A.R.1; Abolhasani M.H.2; Haghi Vayeghan A.1; Amini Chermahini M.3

Received: June 2016 Accepted: October 2016

Abstract Seasonal samplings were conducted over a year to study population dynamic of Carasobarbus luteus in Shadegan Wetland. Samples were collected from five sampling stations in Shadegan Wetland (Salmane, Rogabe, Khoroosi, Mahshahr and Atish) from April 2014 to March 2015. From total number of 1608 samples, 276 individuals were male and 1332 individuals were female. Length-weight relationship was W=0.013L3.0124 (R2=0.92) for males; and W=0.0136L3.0117 (R2=0.91) for females, showing an isometric growth pattern. Condition factor (K) was calculated to be 1.308±0.15 and 1.368±0.17 for the males and females, respectively, showing significant difference between the genders (p<0.05). Also, the results show that this spawns in April-July with a long spawning period and sexual dormant period in autumn to early winter. Mean length at maturation was 161 and 174 mm for males and females specimens; whereas, weight of matured fish was 60 and 80 g for the males and

females, respectively. Growth indices including L∞, growth coefficient and t0 were 305 and 301 mm, 0.67 and 0.55 per year and 0.23 and 0.29 for the males and females, respectively. Natural mortality, fishing mortality, total mortality, Munro Ф' and Downloaded from jifro.ir at 5:43 +0330 on Thursday September 30th 2021 coefficient of exploitation were 1.22 and 1.02 per year, 1.61 and 1.45 per year, 2.83 and 2.47 per year, 2.79 and 2.72, and 0.57 and.59, respectively for the males and females.

Keywords: Carasobarbus luteus, Shadegan Wetland, Growth and fishing indices, Von- Bertalanffy equation

1-Department of Fisheries, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran 2-Department of Natural Resources, Faculty of Agriculture, Islamic Azad University, Khorasgan, Isfahan, Iran. 3-Behbahan Khatam Alanbia University of Technology, Khoozestan, Iran Corresponding author’s E-mail: [email protected]

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Introduction found in the middle and lower parts of Population dynamics is one of the rivers, preferring standing waters near functional sub-divisions of population aquatic plants and algae (Coad, 2006). ecology and fundamentals of fish stock Increased demand for C. luteus has biology (Biswas, 1993). Population caused increased pressure on this dynamic elements are fundamental of species population (Hashemi et al., analytical models in the field of stock 2012); therefore, study on biological assessment, which provide important characteristics, population structure and information about stocks’ status (King, growth factors are important for this 2007). Estimation of length at species. With an area of 537700 ha (the maturation, spawning time, area varies in different years), Shadegan determination of fishing prohibition Wetland encompasses about 34% of the time and optimum length for catch is total wetlands of Iran according to the important information about a fish Ramsar Convention (1971). Shadegan species. Population dynamics is related Wetland is located at 3°,17′-3°,48′ N to sequential processes of regeneration and 48°,17′-48°,50′ E (Bogutskaya et and production, which are known as al., 2008). The aim of this study was to growth and mortality. Stocks’ estimate length at maturation and conservation is a global important key spawning time and to determine fishing factor in sustainable exploitation of prohibition time and optimum length whole aquatic resources. Fisheries for catch of C. luteus. authorities focus on providing enough and assured food from natural resources Materials and methods considering the allowable exploitation Samplings were conducted seasonally (Jenning et al., 2000). Population over a year. Five sampling stations dynamics is one functional sub- including Salmane (30°,40′N: Downloaded from jifro.ir at 5:43 +0330 on Thursday September 30th 2021 divisions of the population ecology and 48°,28′E), Mahshahr (30°,52′N: fundamentals of fish stock biology 48°,30′E), Rogabe (30°,41′N: (Biswas, 1993). Carasobarbus luteus 48°,33′E), Khoroosi (30°,39′N: (Heckel, 1843) is a freshwater fish 48°,40′E) and Atish (30°,54′N: belonging to Carasobarbus sp. and 48°,40′E) were selected in such a way family. The maximum and to cover the whole wetland area (Fig. average length of C. luteus is 38 and 23 1). cm, respectively (Ahmed, 1982; Borkenhagen, 2005). This species is

Iranian Journal of Fisheries Sciences 17(2) 2018 359

Figure 1: Five sampling stations in Shadegan Wetland.

Length-weight relationship fish condition over the year, using the Measurement of fish length and weight following formula (Beckman, 1984): along with the fish age provides useful K= W×102/L3 information about the stock population Where “W” was the fish weight (g) structure, age of maturation, life span, and “L” was total length (cm). mortality, growth and production. The Sexual maturation stages were following formula was used to calculate determined both macroscopically and relationship between the fish total microscopically (7-stage key) and length and weight: stages higher than 4 were considered as W=aLb matured (Biswas, 1993; Sparre and Where, W was fish weight (g), L was Venema, 1998; King, 2007).

Downloaded from jifro.ir at 5:43 +0330 on Thursday September 30th 2021 fish length (cm), “a” was constant Fishes are matured just after reaching coefficient, and “b” was the equation a certain size; therefore, length- power. maturation relationship is as useful as The following formula was used to length-age relationship (King, 2007). find significant differences between the Logistic model and Y=1/(1+exp(-a- calculated “b” and B-3 for a fish with bX)) equation were used to estimate similar growth: length at the first maturation; where, t = [(SdX)/(SdYy)] × [│b-3│/ (√ (l-r2)] “Y” is the proportion of matured males × [√ (n-2)] and females to whole fish within a same Where SdX is standard deviation of length class, “X” is total length (cm) fork length natural log, SdY is standard and “a” and “b” are constant deviation of weight natural log, “b” is coefficients (Biswas, 1993; Sparre and slope, r2 is coefficient of determination Venema, 1998; King, 2007). and “n” is sample size (Zar, 1996). Calculation of length-age relationship is Condition factor or quality factor was important in fish growth study. All calculated to investigate trend of the analytical methods for stock

360 Ghorbani et al., Population dynamics of Carasobarbus luteus in…

assessment, population dynamic and parameters and conversion of length fish management are based on this mode of each longitudinal class to information (Sparre and Venema, relative age. Proportion of fish number

1998). Infinite length (L∞) is defined as in each longitudinal class is calculated the maximum length that the fish of a monthly (Gayanilo et al., 2003). stock are able reach to. There are

several methods to estimate L∞ (Sparre Coefficient of natural mortality (M) and Venema, 1998), which Powell- Natural mortality is defined as that Wetherall graph in the present study. caused by factors other than fishing. These factors include hunting by other Calculation of K with Shepherd method , food deprivation, global

Similar to L∞, K is one of the Von- climate change stresses, diseases and Bertalanffy equation growth aging. Pauly experimental formula was

parameters. After calculation of L∞, K used to calculate coefficient of natural is calculated using FiSAT software mortality (M) in the present study:

(Gayanilo et al., 2003). The shepherd Ln(L∞)=0.0152– 0.279 Ln(L∞) + 0.6543 program of FiSAT software estimates Ln(K) + 0.463 Ln(T) the K curve best fitted on longitudinal Where M is annual coefficient of

histograms (Pauly et al., 1998). natural mortality, L∞ is infinite length (cm), K is curve parameter of Von- Growth performance index Bertalanffy growth equation and T is Munro Ф' test is used to compare the mean ambient temperature (King, growth indices in the studied area 2007). Coefficient of fishing mortality (Pauly, 1984): (F) is calculated from total mortality

Ф' = Log(K) + 2Log(L∞) and natural mortality using the

Where L∞ is infinite length, K is following formula: Downloaded from jifro.ir at 5:43 +0330 on Thursday September 30th 2021 growth coefficient and Ф' is growth F = Z – M index. Coefficient of exploitation calculation (E)

t0 calculation Coefficient of exploitation is calculated

The optimum T0 is calculated according using this formula: E=F/Z. If E is lower to experimental formula of Pauly than 0.5, the stock is underexploited. If (Froese and Binohlan, 2000): the stock is overexploited, the value of

Log (-t0)=-0.3922-0.2752 Log(L∞) - E would be higher than 0.5. In fact, the 1.038 Log(K) E value is optimum when fishing mortality is equal to natural mortality; Total mortality (Z) so that E =0.5 (King, 2007). Coefficient of total mortality is calculated using the method of Production/biomass ratio or population longitudinal frequency to catch curve production (P/B) conversion. In this method, total Production/biomass or population mortality is calculated using growth production (specific production) is

Iranian Journal of Fisheries Sciences 17(2) 2018 361

calculated using this formula P/B = for the males and 175-195 (41.42%) -0.35 2.64Wmat ; where Wmat is fish weight and 275-295 (0.07%), respectively at maturation (Randall and Minns, (Table 1). 2000). Table 1. Longitudinal classification and frequency percentage of longitudinal classes Virtual model of population analysis of Carasobarbus luteus in Shadegan Wetland Virtual model of population analysis in 2014-2015. and cohort analysis are obtained using Longitudinal Frequency Frequency classification(mm) (%) male (%) female FiSAT program. The value of L∞, K, M, 95-115 1.12 0.43 F, a (constant) and b (power) are used 115-135 11.57 3.76 135-155 25.37 13.86 as inputs for the model. t0 is considered 155-175 35.82 40.82 zero. VPA functional methods have 175-195 22.01 28.03 been determined by Pauly (Pauly, 195-215 2.99 8.06 215-235 1.12 3.01 1984). These analyses were conducted 235-255 0 1.39 in SPSS, Minitab and FiSATII 255-275 0 0.53 software. 275-295 0 0.11

Length-weight relationship was Results W=0.013L3.0124 (R2=0.92) for males; This study was conducted in Shadegan W=0.0136L3.0117 (R2=0.91) for females Wetland and a total number of 1608 (Fig. 2). The value of standard error fish were sampled that underwent was low (<0.5), so that keeps the b biometry. 276 samples were male and value within isometric growth range. 1332 samples were female. Mean There was no significant difference length (length range) in the males was between the calculated b and expected 161±28 (110-222) mm, whereas it was B (=3) values. The value of b in the fish 174±38 (95-280) mm in the females. Downloaded from jifro.ir at 5:43 +0330 on Thursday September 30th 2021 length-weight relationship was near 3, Mean weight (weight range) in the which is due to their isometric growth. males was 60±31 (15-175) g, whereas it The minimum and maximum condition was 80±39 (15-370) g in the females. factors in the males and females were Mean length (length range) of whole observed in May and January. samples was 217±58 (95-280) mm, Condition factor (K) was calculated to whereas mean weight (weight range) of be 1.308±0.15 and 1.368±0.17 for the whole samples was 164±120 (15-370) males and females, respectively, g. Data classification was performed showing significant difference between with 20 mm intervals. Longitudinal the genders (p<0.05). Overall, the males classes and frequencies of C. luteus are had lower condition factor than females presented in Table 1. The maximum and the maximum and minimum values and minimum longitudinal frequencies were observed in winter and spring. are 155-175 (25.37%) and 95-115 (0%)

362 Ghorbani et al., Population dynamics of Carasobarbus luteus in…

200 y = 0.013x3.0124 male R² = 0.9203 male

150

100

TL (mm) TL 50

0 0 5 10 15 20 25 Wt (g) 400 female 350 y = 0.0136x3.0117 300 R² = 0.9131 Female

250 200

150 TL (mm) TL 100 50 0 0 5 10 15 20 25 30 Wt (g) Figure 2: Length-weight relationship in male (A) and female (B) Carasobarbus luteus in Shadegan Wetland. 2.5

a

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1.5 c 1 d Condition Factor Condition 0.5

0 Spring Summer Fall Winter Season

Figure 3: Condition factor in different seasons in Shadegan Wetland.

Frequency of different gonadal spawning of C. luteus occurs in April- developmental stages was determined July with a long spawning period and using the 7-stage key and is presented sexual dormant period in autumn to in Fig. 4. This figure shows that early winter.

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100 stages 7 80 stages 6 60 stages 5 40 stages 4 20 stages 3 MaturityPercent 0 stages 2

Month

Figure 4: Spawning stages of Carasobarbus luteus in Shadegan Wetland.

LM50 curve (the length at which 50% of mm for whole individuals); whereas, the fish are matured) was obtained weight at maturation was 42 and 100 g, according to the fish longitudinal respectively. P/B was 0.71 and 0.52, classification and frequency of matured and consumption to biomass ratio was individuals in each class. Length at 15.41 and 12.37 for the males and maturation was 152 and 139 mm for the females, respectively. males and females, respectively (150

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Figure 5: Length at maturation in male (A) and female (B) Carasobarbus luteus in Shadegan Wetland.

L∞ was 305 and 310 mm, growth 1.61 and 1.45 per year, total mortality coefficient was 0.67 and 0.55 per year, was 2.83 and 2.47 per year, Munro Ф'

and time for t0 was -0.23 and -0.29 for was 2.79 and 2.72, and coefficient of the males and females, respectively exploitation was 0.57 and 0.59 per year (Fig. 6). Natural mortality was 1.22 and in the males and females, respectively 1.02 per year, fishing mortality was (Fig. 7).

364 Ghorbani et al., Population dynamics of Carasobarbus luteus in…

Figure 6: Growth coefficient of the male (A) and female (B) Carasobarbus luteus in Shadegan Wetland. Downloaded from jifro.ir at 5:43 +0330 on Thursday September 30th 2021

Figure 7: Catching curve obtained from longitudinal frequency data of the male (A) and female (B) Carasobarbus luteus in Shadegan Wetland.

Von-Bertalanffy equation for the male Using the curve, length of C. luteus and female C. luteus population in 2015 was calculated for each longitudinal

was Lt=305 (1- exp (-0.67(t+0.23))) and class based on virtual population

Lt=310(1-exp(-0.55(t+0.29))), analysis. In males, probability of catch

respectively. In this equation Lt is the maximizes in longitudinal class of 20 fish fork length (mm) and t is the fish cm and falls afterward. In females, age (year). probability of catch maximizes in longitudinal class of 18 cm and

Iranian Journal of Fisheries Sciences 17(2) 2018 365

fluctuates afterward. Considering the spawning style, age and aquatic virtual population analysis for either of resource type (King, 2007). C. luteus the genders, survivorship falls and spawns in Shadegan Wetland in spring, fishing mortality elevates along with which is similar to what has been increase in the fish length from 15 cm reported in Hoorolazim Wetland. to higher values (Fig. 7). Studies on sexual maturation stages and Fig. 6. Virtual analysis of population percentage of matured (C.luteus in obtained from longitudinal frequency Hoorolazim Wetland show that the data of the male (A) and female (B) C. highest number of matured fish is luteus in Shadegan Wetland present in April. This suggests that percentage of the matured fish increases Discussion in late winter with temperature The biometry data show that the fish elevation, which finally spawn in the weight and length elevation reduces in middle of spring (May and June), which higher ages and females usually have is somehow in line with other studies. higher weight and length than males. In the other regions, most sp. Differences in length-weight species spawn in late winter to early relationships of C. luteus were reported spring, and such a negligible difference from different geographical regions, in spawning time is related to which is due to variations in the environmental characteristics and water condition of the regions. In Shadegan temperature (Dutta et al. 2012). Wetland, higher weight was observed at Considering other studies on C. luteus,

same lengths in some stations, which it seems that L∞ of this species is higher may be related to nutritional conditions. in Turkey and Syria than that in Iran

Variation in length-weight relationships and Iraq; in other words, L∞ is higher in may be due to seasonal variations, cold water than in warm water. Downloaded from jifro.ir at 5:43 +0330 on Thursday September 30th 2021 environmental factors, fish However, variation of L∞ and other physiological condition at sampling growth indices in different regions may time, gender, gonad developmental be due to quality and quantity of feeds stage and nutritional conditions in the and climatic conditions (Bartulovic et environment (Yildirim et al., 2002). al., 2004). Several factors can affect Trend of K data shows that the fish growth including age, gender, maximum and minimum values are season, year, nutrition, physiological observed in pre-spawning (winter) and conditions, feed availability and spawning (spring), respectively, and the reproduction cycle (Dutta et al. 2012). mean K values of the females were Population size of a species is higher than those of the males. dependent on survival and reproduction Generally, male and female populations success and considering the constant have similar K value pattern. Variation fluctuation in environmental conditions, of K values in different regions is each species should adapt different related to several factors including conditions, otherwise cannot survive. population density, diseases, nutrition, Therefore, growth parameters of a

366 Ghorbani et al., Population dynamics of Carasobarbus luteus in…

species show fluctuations in different environmental factors that affect the years and should be investigated in stock survival are the factors causing different times (Cengiz, 2012). pressure on the stock (Mateus and Comparison of length at maturation of Estupina, 2002). It seems that P/B or C. luteus between Shadegan and population production (specific Hoorolazim Wetlands suggest that the production) of C. luteus is not high in Shadegan population matures earlier Shadegan Wetland. P/B of inland water than the population in Hoorolazim. fish ranges from 0.2-3 and usually is Length at maturation varies among higher in warm regions compared to different species depending on cold regions. Population production environmental conditions, life span and (specific production) can indicate fish feed type; also, environmental factors population growth potential in respect directly affect age and length at to habitat production capacity (Jenning maturation (Dutta et al., 2012). No et al., 2000). P/B is more important

systemic trend was observed in t0 than production; because if P/B of values in different sampling stations different organisms of an ecosystem is being -0.37 for the whole sampling available, production of a certain satiations of Shadegan Wetland. Age at regions can be calculated and zero length varies in different regions populations with different biomasses depending on environmental factors and can be compared among different

change in L∞ and growth coefficient. regions. Feed consumption rate (Q/B) Age at zero length elevates along with of C. luteus is high, which was

growth coefficient elevation and L∞ expected regarding the fact that this demotion (Sparre and Venema, 1998). species is omnivorous. Palomares and Ф' value ranges 2.3-2.93 being 2.3 Pauly (1999) reported that fishes with (Hashemi et al., 2011) for Shadegan forked caudal fin have higher aspect Downloaded from jifro.ir at 5:43 +0330 on Thursday September 30th 2021 Wetland. Variations in ecological ratio and consume more feed, which is conditions and latitude may affect in line with the present study. Virtual infinite length and growth coefficient, population analysis for each which in turn affect Ф', and even in a longitudinal class showed that catch single region, variable values are probability for C. luteus increases along observed at different time because of with the fish length elevation up to 18 variation in environmental conditions cm (maximum fishing mortality) and (Sparre and Venema, 1998). Coefficient fluctuates thereafter. Also, according to of exploitation (E) of this species was results it showed that females are more higher than 0.5; thus, the stock is abundant and have higher fishing overexploited. Coefficient of mortality than males. exploitation of higher than 0.5 along with higher fishing mortality compared References to natural mortality show the stock is Ahmed, H.A., 1982. Crowth (sic) of under overfishing pressure (King, the cyprinid fish, Barbus luteus 2007). Catching size quantity and (Heckel) in Tharthar Reservoir, Iraq.

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