Growth, Mortality, Recruitment and Yield of Rainbow Trout, Oncorhynchus mykiss Walbaum, 1792 in Karacaören-I Dam Lake, Turkey

Mehmet Cilbiz1* and F. Banu Yalim2

1Fisheries Research Institute, Eğirdir, Isparta-32500, Turkey

2Mediterranean Fisheries Research, Production and Training Institute, Kepez Unit, 07192, Antaya, Turkey

ABSTRACT

In this study, growth parameters (i.e. condition factor, length-weight relationship, K, L∞, t o), mortality rate (Z, M, and F), recruitment pattern and yield were investigated for Oncorhynchus mykiss in Karacaören I Dam Lake. Fish were collected on monthly basis between July, 2013 and June, 2014. Growth parameters were analyzed by ELEFAN with monthly length–frequency data. The b values of the length-weight relationship, mean condition factor, K (growth coefficient), L∞ (asymptotic length) and t o were estimated as 3.207, 1.13, 0.33 year-1, 36.50 cm and -0.476 years, respectively. Total mortality (Z) by length-converted catch curve was estimated at 0.83 year-1, fishing mortality (F) 0.14 year-1, natural mortality (M) 0.69 year-1 and exploitation rate (E) 0.17. According to the result of Relative Yield/Recruit analysis estimated E max>E, so in this context stock of O. mykiss was not overexploited in Karacaören I Dam Lake.

Article Information

Received 03 August 2016

Revised 27 August 2016

Accepted 30 September 2016

Available online 26 April 2017

Authors’ Contributions

Both authors conceived and designed the study. MC collected and analyzed data and wrote the article.

Key words

Oncorhynchus mykiss, Rainbow trout, Length-weight relationship, Condition factor, Recruit analysis, Van Bertalanffy growth curve.

DOI: http://dx.doi.org/10.17582/journal.pjz/2017.49.3.825.832

* Corresponding author: mehmetcilbiz@hotmail.com

0030-9923/2017/0003-0825 $ 9.00/0

Copyright 2017 Zoological Society of Pakistan

Introduction

Native range of Oncorhynchus mykiss is the Eastern Pacific Ocean and the freshwaters, mainly west of the Rocky Mountains, from northwest Mexico (including extreme northern Baja, California) to the Kuskokwim River, Alaska. It is probably native in the drainages of the Peace and Athabasca rivers east of the Rocky Mountains (MacCrimmon, 1971; NOBANIS, 2015). Nowadays except for certain parts of tropical areas it has reached a global distribution area throughout the world. This distribution is based on human activity such as amateur fishing and aquaculture. O. mykiss was brought from Germany at first in 1970. Then its aquaculture started in Turkey (Çetinkaya, 2006). This fish is now distributed over large areas of Turkey’s inland waters due to the proliferation of aquaculture locations. This fish is included in IUCN’s (International Union for Conservation of Nature) list of 100 World’s Worst Invasive Alien Species, though Çetinkaya (2006) has reported that there is no invasive risk of O. mykiss because of its inability to create fertile population in Turkey. On the contrary, Küçük and İkiz (2004) have reported that this species has ability to reproduce in some natural waters of South-West Mediterranean region of Turkey. Similarly, Candiotto et al. (2011) have reported that in some cases, O. mykiss can constitute self-sustaining stable populations. Davis (2012) has likewise reported that hatchery raised rainbow trout have the ability to reproduce and become naturalized to reservoir systems and also wild rainbow trout are recruiting to the adult population in Deerfield Reservoir.

The population of O. mykiss is increasing year by year. The total production was 277 t in 2000, which increased to 438 t in 2013. This production contributed around 980,000 US$ in national economy (TUIK, 2015).

In the previous studies, Leiner (1995) studied growth, mortality and production of brown and rainbow trout in 32 sites on 15 streams of New Mexico. Candiotto et al. (2011) studied biology of one of the rare European spawning populations of O. mykiss in Italian stream. Korman et al. (2012) studied recruitment dynamics and movement of rainbow trout in the Colorado River in Grand Canyon using an integrated assessment model.

For evaluation of commercial fish stock we have studied here the growth, mortality, recruitment and yield of O. mykiss. It is hoped that the results of this study will improve our understanding of population dynamics of O. mykiss in Karacaören-I Dam Lake.

Materials and Methods

Study area

The Karacaören-I Dam Lake is located in limits of the cities Isparta and Burdur province (West South Anatolia) (Fig. 1). Surface of the lake is 45.5 km2, maximum depth is 65 m and altitude is 85 m (Ozvarol and Ikiz, 2009). Fish sampling was carried out on monthly basis, at two different stations with a total of 24 trials, during July 2013 and June 2014. Sampling station depths were between 6-9 m. Gillnets were made of monofilament material with 3.2, 4, 5, 6, 7, 8 and 9 cm stretched mesh sizes with 0.20 mm rope thickness and hanging ratio of 0.50. Depths of all nets were 50 meshes which were 100 m long for each panel. All nets were set in the afternoon and retrieved the following morning. The fork length (FL) of the fish was measured to the nearest 0.1 cm with a measuring board and weight recorded with 1g precision digital scale.

Length-weight relationship and condition factor

Fishes had nonlinear relationship between length and weight that can be expressed as W= aL b (Froese et al., 2011), where W= weight of the samples in g, L= length of the samples in cm, a and b are constant parameters of the regression equation. In the calculation of condition factor (C) the formula of Fulton’s coefficient of condition factors C = (W*100)/L 3 (Ricker, 1975) was used.

Growth analysis

The FISAT II software (Gayanilo et al., 2005) was used to analyze the monthly length-frequency data. Estimates of the growth parameters, L∞ (asymptotic length), and K (growth coefficient) for the von Bertalanffy growth function (VBGF), were derived from the length frequency data using the ELEFAN I routine incorporated in the FISAT II. Algorithms of the routine require that the L∞ parameter is known, at least within a biologically acceptable range. Initial values of L∞ were obtained using the Powell–Wetherall method as modified by Pauly and Soriano (1986).

The ELEFAN program uses a nonparametric method to fit the von Bertalanffy growth curve through modes. The best curve will pass through the maximum possible number of modes, and the goodness of fit index (Rn) is defined by Rn = 10 ESP/ASP/10 (ESP: Explained Sum of Peaks, ASP: Available Sum of Peaks) (Ye et al., 2014).

The value of t o was obtained from the equation Log (-t o) = -(0.3922)-0.2752 log(L∞)-1.038 log(K) (Pauly, 1983). The standard growth index (ɸ) was used as a measure of overall growth performance (Moreau et al., 1986). The index is defined as ɸ ′= log K + 2 log L∞.

Estimation of mortality rates

Mortality was estimated for the total sampling period. Length-converted catch curve was used to estimate total annual instantaneous mortality rates (Z) (Memon et al., 2016). The right descending arm of this curve was fitted with a regression line. The regression equation has the form ln(N) = a + bt′, where N is the number of fish in pseudo-cohorts ‘sliced’ by means of successive growth curves, tˈ is the relative age of the fish in that pseudo-cohort, and b with the sign changed provides an estimate of Z. To obtain an independent estimate of natural mortality rate (M), the equation of Pauly (1980) log (M) = -0.0066-0.279 log (L∞) + 0.6543 log (K) + 0.4634 log (T) was employed. Here, T means annual habitat temperature (19.5 °C).

Estimation of recruitment pattern

Recruitment patterns were determined from the routine implemented in FISAT II, which involved backward projection of the length frequency data onto the time axis based on the estimated growth parameters (Moreau and Cuende, 1991; Ye et al., 2014).

Estimation of relative yield per recruit

The model of Beverton and Holt (1956) as modified by Pauly and Soriano (1986) was used to estimate relative yield-per-recruit (Yˈ/R) and relative biomass per-recruit (Bˈ/R) for O. mykiss. Both the ogive selection method and the knife-edge selection method were used. From these, the values of exploitation rate giving maximum relative yield-per-recruit (E max) was estimated. E max (exploitation rate producing maximum yield), E 0.1 (exploitation rate at which the marginal increase of Yˈ/R is 10% of its virgin stock) and E 0.5 (the exploitation rate under which the stock is reduced to half its virgin biomass) were computed through the first derivative of the function (Uneke et al., 2010).

RESULTS

In the fishing trial we caught 166 O. mykiss species fork lengths of which were between 13.6-34.5 cm. Generally, more samples were collected during winter months than in other seasons. O. mykiss could not be obtained in June, July and August. Monthly catch composition is given in Table I and length-frequency distribution is shown in Figure 2.

Figure 3 shows a nonlinear relationship between length and weight of O. mykiss population. Regression model parameters calculated as a= 0.006; b=3.207 [3.162-3.252], R 2= 0.968 and p˂0.001. Using these parameters in the equation (W=a*L b) (Froese et al., 2011) and ultimately length-weight relationship equation gave the estimate as W=0.006*L 3.207. In this study O. mykiss showed positive allometric growth pattern (b>3).

Mean condition factor of O. mykiss population in Karacaören-I Dam Lake was calculated as 1.13 (min.= 0.85, max.= 1.61 and SE= 0.01).

Powell-Wetherall plot of O. mykiss is shown in Figure 4. Black points in Figure 4A were used for the regression analysis (Y= 7.29+ (-0.220)*X, r 2= 0.977, L∞=33.08 cm and Z/K= 3.538).

Table I.- Monthly catch composition of O. mykiss.

Sampling period | N | Fork length | Total weight
Mean + SEM (Min - Max) | Mean + SEM (Min - Max)
Oct 2012 | 1 | 19.5 + 0.00 (19.5-19.5) | 94.0+ 0.00 (94.0-94.0)
Nov 2012 | 6 | 25.8 + 0.3 (25.0-27.0) | 194.5 + 2.4 (189.0-205.0)
Dec 2012 | 61 | 18.6 + 0.5 (13.6-29.5) | 83.2 + 8.6 (33.0-321.0)
Jan 2013 | 25 | 17.6 + 0.3 (14.5-22.4) | 56.3 + 3.0 (35.0-101.0)
Feb 2013 | 40 | 19.6 + 0.4 (15.3-29.5) | 89.1 + 8.9 (40.0-315.0)
Mar 2013 | 7 | 21.0 + 1.6 (15.5-28.8) | 141.3 + 34.7 (75.0-337.0)
Apr 2013 | 19 | 25.6 + 0.7 (18.0-31.8) | 210.9 + 16.5 (76.0-383.0)
May 2013 | 7 | 28.5 + 1.2 (25.8-34.5) | 330.3 + 43.0 (236.0-554.0)

The growth pattern, which was von Bertalanffy growth curves of O. mykiss is shown in Figure 5. Parameters of the von Bertalanffy growth equation were indicated by ELEFAN as L t=36.50[1-exp-0.33(t+0.4760)] and W t=583.87[1-exp-0.33(t+0.4760)]3.207 (L∞=36.50 cm FL, W∞=583.87 g, K=0.33 year-1, t o=-0.4760 years, SS=8, SL=31.50, Rn=0.597 and ɸ=2.64).

In the population of O. mykiss, there was one recruitment peak in a year (Fig. 6). This peak was in June with 18.38% recruitment. Most of the recruitments occurred in spring (i.e. March 15.92%, April 15.63%, May 16.67%).

The computed length-at-first-capture L25, L50 (or Lc), and L75 were 13.84, 14.11 and 14.37 cm, respectively (Fig. 7). Total mortalities (Z) calculated by non-seasonalized length-converted catch curves were 0.83 year-1. Catch curve is shown in Figure 8. Natural mortality was estimated as M= 0.69 year-1 (annual mean water temperature was evaluated

as 19.5 oC). Fishing mortality coefficient F was 0.14 year-1. E (exploitation rate) was computed as 0.17. Annual survival rate was estimated as 43.60%, 9.52% and 46.88% for S (survive), C (fishing), D (natural), respectively.

Using the Knife-Edge selection procedure for the analysis of relative yield and biomass per recruit of O. mykiss (Fig. 9) gave an E max, (the value of exploitation rate E giving the maximum relative yield per recruit) of 0.618, E 0.1 (the value of E at which increase in the Yˈ/R is 10% of its value) of 0.520 and E 0.5 (the value of E at 50% of the unexploited relative biomass per recruit) of 0.327 (Table II). Selection ogive procedure of O. mykiss is shown in Figure 9. E 0.1, E 0.5 and E max values estimated as 0.517, 0.316 and 0.618, respectively, based on ogive procedure.

Discussion

The reason for low or no fish catch during June, July and August is because of high water temperature. The decrease in water depth may also be cause of sudden rise of water temperature which makes the fish to move to deeper lake area or relatively colder spring waters supporting the Dam Lake.

In this study, O. mykiss population of Karacaören-I Dam Lake’s showed positive allometric growth proportion (b>3). This result showed parallelism with other studies which were conducted in Turkey (i.e. Erguden and Goksu, 2009; Çiçek and Birecikligil, 2013). But our b value was different from the one reported by Leiner (1995),

Table II.- Result of Relative Yield/Recruit Analysis for O. mykiss (L c/L∞=0.380; M/K=2.09).

Parameters | Knife edge selection | Ogive selection
E 0.1 | 0.520 | 0.517
E 0.5 | 0.327 | 0.316
E max | 0.618 | 0.618

Table III.- Summary of previous biology studies on O. mykiss.

| Parameters | Location | Author
N | a | b | r 2
Length-weight relationship | 157 | -4.698* | 2.88 | 0.96 | Rio Gr.,Str, New Mexico | Leiner (1995)
16 | -4.377* | 2.73 | 0.94 | Red Stream, New Mexico
8 | -5.687* | 3.30 | 0.98 | Pecoz Stream,New Mexico
39 | 0.004 | 3.29 | 0.92 | Seyhan Dam Lake, Turkey | Erguden and Goksu (2009)
794 | 0.00005 | 2.69 | 0.98 | Lemme Creek, Italy | Candiotto et al. (2011)
359 | -4.921* | 2.96 | 0.99 | Dachigam Stream, India | Shah et al. (2011)
87 | 0.0066 | 3.19 | 0.99 | Ecemiş Stream, Turkey | Çiçek and Birecikligil (2013)
70 | 0.902 | 3.39 | 0.86 | Kashmir Valley, India | Sharma and Bhat (2015)
166 | 0.006 | 3.20 | 0.96 | Karacaören-I D.L. Turkey | Present Study
Condition factor | K_Mean | K_Min | K_Max |  |
- | 0.76 | 1.08 | Flaming Gorge, USA | Budy et al. (2003)
1.15 | - | - | Dachigam Stream, India | Shah et al. (2011)
| 1.83 | - | - | Kashmir Valley, India | Sharma and Bhat (2015)
| 1.13 | 0.85 | 1.61 | Karacaören-I D.L. Turkey | Present Study
Age | Class | Min. | Max. |  |
| 6 | 2 | 7 | Mimbres Str., New Mexico | Leiner (1995)
| 5 | 0 | 4 | Red Stream, New Mexico
| 6 | 0+ | 5+ | Sacramento River, USA | Glowacki (2003)
| 2 | 3 | 4 | Kadıncık Stream, Turkey | Korkmaz (2004)
| 5 | 0+ | 4+ | Lemme Creek, Italy | Candiotto et al. (2011)
| 2 | 2+ | 3+ | Karakaya D.L. Turkey | Ateşşahin et al. (2011)
| 6 | 0+ | 5+ | Karacaören-I D.L. Turkey | Present Study
Growth parameters | L∞ | K | t o |  |
37.63 | 0.080 | -1.630 | Mimbres Str., New Mexico | Leiner (1995)
29.13 | 0.390 | -0.360 | Red Stream, New Mexico
36.50 | 0.330 | -0.476 | Karacaören-I D.L. Turkey | Present Study
Mortality rate | Z | M | F | E |  |
0.42 | - | - | - | Mimbres Str., New Mexico | Leiner (1995)
0.46 | - | - | - | Red Stream, New Mexico
0.83 | 0.69 | 0.14 | 0.17 | Karacaören-I D.L. Turkey | Present Study

*Log(a).

Candiotto et al. (2011) and Shah et al. (2011) (Table III). The mean condition factor estimated as 1.13 is similar to that reported by Shah et al. (2011) but very low compared to 1.83 reported by Sharma and Bhat (2015). It is thought that this differences may be due to sex ratio distributions, feeding status, age distributions, number of samples and sampling period.

While estimated K value (0.33) is similar to (0.39) that reported by Leiner (1995) for Red stream O. mykiss population, it is different from that of Mimbers stream population (0.08) reported by same author. It is assumed that this difference is because of different number of samples, sampling methods (i.e. gillnet vs electro shockers) and origin of rainbow trout. Davis (2012) reported that wild fish exhibited faster growth than the rainbow trout raised in a hatchery and he developed a non-lethal method to differentiate between hatchery-raised and naturally reproduced rainbow trout based on growth characteristics of scales.

It could not be explicitly determined that whether recruitment of O. mykiss in Karacaören I Dam Lake was based on self-sustaining individuals or due to escape from the nearby aquaculture facility every year. Davis (2012) reported that managers should focus on continuing to monitor genetic contribution to natural reproduction by hatchery-reared rainbow trout and also fisheries biologists should focus on continuing to improve non-lethal technique to continue to monitor recruitment.

In the light of relative yield and biomass recruit information, it can be concluded that there are no serious fishing pressures on stock, since the estimated E max with knife-edge selection (0.618) and ogive selection (0.618) greater than current exploitation rate (E = 0.17). The main target of fishermen are common carp (Cyprinus carpio) and Prussian carp (Carassius gibelio) in Dam Lake, so fishermen use gillnet and trammel nets with 100-110 mm stretched mesh size intended for this species. These nets are very inefficient in O. mykiss fishing due to very large size of this species. Estimated fishing mortality (F=0.14) may originate from pikeperch’s (Sander lucioperca) nets or tangling with teeth on carps nets. The anglers probably cause least fish mortality.

Conclusion

It shows that O. mykiss stock is not use within economic ratability scope due to most of the deaths based on natural. Because of gillnets are inefficient in O. mykiss fishing (Cilbiz et al., 2015), angling may be encourage in Karacaören I Dam Lake for better exploiting of the O.mykiss stock.

Acknowledgements

This study founded by Republic of Turkey, Ministry of Food Agriculture and Live Stock with TAGEM/HAYSUD/2013/A11/P-02/7 project number.

Conflict of interest statement

We declare that we have no conflict of interest.

REFERENCES

Ateşşahin, T., Dartay, M., Duman, E. and Gül, M.R., 2011. Fishing efficiency and fishing rainbow trout (Oncorhynchus mykiss) in Karakaya Dam Lake in Turkish. Res. J. Bio Sci., 4: 113-117.

Beverton, R.J.H. and Holt, S.J., 1956. A review of methods for estimating mortality rates in exploited fish populations with special reference to sources of bias in catch sampling. Rapp. P.V. Reun. Cons. Int. Explor. Mer., 140: 67-83.

Budy, P., Thiede, G.P. and Haddix, T., 2003. Rainbow trout growth and survival in Flaming Gorge Reservoir. USGS Utah Cooperative Fish and Wildlife Research Unit Department of Aquatic, Watershed, and Earth Resources Utah State University.

Candiotto, A., Bo, T. and Fenoglio, S., 2011. Biological and ecological data on an established rainbow trout (Oncorhynchus mykiss) population in an Italian stream. Fundam. appl. Limnol., 179: 67-76.

Cilbiz, M., Yalım, F.B., Korkmaz, B. and Yener, O., 2015. Determination of gillnet efficiency and selectivity of rainbow trout fishing (Oncorhynchus mykiss Walbaum, 1792) in Karacaören-I Dam Lake [in Turkish]. 2nd Syposium on Fish Indroduction and Reservior Management, May 20-22, 2015-Eğirdir-Isparta.

Çetinkaya, O., 2006. Exotic and native fish species that introduced or stocked into turkish waters, their impacts on aquaculture, fisheries, wild populations and aquatic ecosystems: A preliminary study on constructing a database [in Turkish]. Ist Fish Indroduction and Reservuar management Symposium, 07-09 February 2006, Antalya.

Çiçek, E. and Birecikligil, S., 2013. The length-weight relationships of Oncorhynchus mykiss and Salmo trutta magrostigma in Ecemiş Creek (Nigde) [in Turkish]. 1st National Zoology Congress, University of Nevşehir, Depertmant of Biology. 28-31 Agust, 2013, Nevşehir.

Davis, J.L., 2012 Contribution of natural recruitment to the rainbow trout Oncorhynchus mykiss sport fishery in Deerfield Reservoir. Master thesis, South Dakota State University.

Erguden, S.A. and Goksu, M.Z.L., 2009. Length–weight relationships for 12 fish species caught in Seyhan Dam Lake in southern Anatolia, Adana, Turkey. J. appl. Ichthyol. 25: 501-502. http://dx.doi.org/10.1111/j.1439-0426.2009.01231.x

Froese, R., Tsikliras, A.C. and Stergiou, K.I., 2011. Editorial note on weight-length relations of fishes. Acta Ichthyol. Piscat., 41: 261-263. http://dx.doi.org/10.3750/AIP2011.41.4.01

Gayanilo, F.C., Sparre. P. and Pauly, D.E., 2005. The FAO-ICLARM stock assessment tools (FISAT II) program package, FAO, Rome.

Glowacki, S.C., 2003. A comparison of growth rates of wild rainbow trout (Oncorhynchus mykiss) in the upper Sacramento river before and after the cantara spill of 1991. Master of Science thesis, The Faculty of Humboldt State University.

Korkmaz, A.Ş., 2004. Density and biomass of fish in Kadıncık (Çamlıyayla-Mersin) Brook [in Turkish]. J. agric. Sci., 11: 91-97.

Korman, J., Martell, S.J.D., Walters, C.J., Makinster, A.S., Coggins, L.G., Yard, M.D. and Persons, W.R., 2012. Estimating recruitment dynamics and movement of rainbow trout (Oncorhynchus mykiss) in the Colorado River in Grand Canyon using an integrated assessment model. Can. J. Fish. aquat. Sci., 69: 1827-1849. http://dx.doi.org/10.1139/f2012-097

Küçük, F. and İkiz, R., 2004. Fish fauna of streams discharging to Antalya Bay [in Turkish]. E.U. J. Fish. aquat. Sci., 21: 287-294.

Leiner, S., 1995. Growth, mortality and production of brown and rainbow trout in New Mexico streams. Ribarstvo, 53: 51-62.

MacCrimmon, H.R., 1971. World distribution of rainbow trout (Salmo gairdneri). J. Fish. Res. Bd. Canada, 28: 663-704. http://dx.doi.org/10.1139/f71-098

Memon, K. H., Liu, Q., Kalhoro, M. A., Chang, M. S., Baochao, L., Memon, A. M., Hyder, S. and Tabassum, S., 2016. Growth and mortality parameters of hairtail Lepturacanthus savala from Pakistan waters. Pakistan J. Zool. 48: 829-837.

Moreau, J., Bambino, C. and Pauly, D., 1986. A comparison of four indices of overall fish growth performance, based on 100 tilapia population (Fa. Cichlidae), (eds. J. L. Maclean, L.B. Dizon and L.V. Hosillo). The First Asian Fisheries Forum, Asian Fisheries Society, Manila, Philippines.

Moreau, J. and Cuende, F.X., 1991. On improving the resolution of the recruitment patterns of fishes. Fishbyte, 9: 45-46.

NOBANIS, 2015. European network on invasive species. Available at https://www.nobanis.org/globalassets/speciesinfo/o/oncorhynchus-mykiss/onchorhynchus_mykiss.pdf [Accessed 28 December 2015].

Ozvarol, Z.A.B. and Ikiz, R., 2009. Mortality ratio and stock analysis of Vimba (Vimba vimba tenella (Nordmann,1840)) population ın Karacaoren I Dam Lake (Burdur-Turkey). J. Agric. biol. Sci., 3:143-147.

Pauly, D., 1980. On the Interrelationship Between Natural Mortality. Growth Parameters and Mean Environmental Temperature in 175 Fish Stocks. ICES J. Marine Sci. 39: 179-192. http://dx.doi.org/10.1093/icesjms/39.2.175

Pauly, D., 1983. Some simple methods for the assesment of tropical fish stocks. FAO Fisheries Technical Paper 234. pp. 52.

Pauly, D. and Soriano, M.L., 1986. Some Practical Extensions to Beverton and Holts Relative Yield- Per-Recruit Model. The first Asian Fisheries Forum (pp. 491-496). Asian Fisheries Society, Manila.

Ricker, W.E., 1975. Computation and interpretation of biological statistics of fish populations. Dept. of Fisheries and Oceans.

Shah, T.H., Balkhi, M.U.H., Asimi, O.A. and Khan, I., 2011. Length weight relationship and ponderal index of rainbow trout (Oncorhynchus mykiss W., 1792) from Dachigam stream in Kashmir. Afr. J. agric. Res., 8: 1277-1279.

Sharma, R.K. and Bhat, R.A., 2015. Length-weight relationship, condition factor of rainbow trout (Oncorhynchus mykiss) from Kashmir waters. Annls. biol. Res., 6: 25-29.

TUIK, 2015. Turkey Statistical Institute, Fishery Statistics. Available at http://tuikapp.tuik.gov.tr/medas/?kn=97&locale=tr [Accessed 24 June 2015]

Uneke, B.I., Nwani, C.D., Okogwu, O. and Okoh, F., 2010. Growth, mortality, recruitment and yield of Pellonula leonensis Boulenger, 1917 (Osteichthyes: Clupeidae) in a tropical flood river system. J. Fish. Int. 5: 19-26. http://dx.doi.org/10.3923/jfish.2010.19.26

Ye, S., Moreau, J., Zeng, W., Zhang, T., Liu, J. and Li Z., 2014. Growth and mortality of two small fishes, Toxabramis swinhonis Günther, 1873 and Hyporhamphus intermedius (Cantor, 1842), in a Yangtze shallow lake (China) assessed by length frequency analysis. J. appl. Ichthyol., 30: 479-484. http://dx.doi.org/10.1111/jai.12405