This study was carried out to reveal how the aquaculture activities, located near the stream bed, effect the length-weight relations of native freshwater fish. Fish samples were collected on monthly for one year on the Kocabaş Stream (Çanakkale), a trout farm constructed next to stream. Fish specimens were collected from up and down sections of the trout farm and control station selected from another branch of the stream by electrofishing between August 2015-July 2016. The growth type sign; b value in length-weight relationship indicates that both species are in positive allometry at the down station and isometric growth at the upper station. Fish farm might affect the growth type of both species positively due to contribution of extra food resources originated from the farm via discharge of waste water of trout farm at the down section. However, this hypothesis should be tested by proper growth parameters of the fish species.

Keywords: aquaculture, b value, allometric growth, kocabas stream

It is known that fish farms are a significant source of nutrients for the aquatic environment.^1,2 Especially in aquaculture regions, many studies have been made on the introduction of farm derivated feed that mostly prepared using protein riched native fish.^3–6 The particulates formed by the disintegration of nutrients and organic solids, uneaten pellets and stools released during aquaculture; causing the native fish species and other animals to be fed into the aquaculture field.^7–10 The accumulation of organic matter under the cages during aquaculture has been shown to cause changes in the benthic and phytoplankton communities such as abundance, dominance and species diversity.^11,12

Barbus oligolepis is a bentopelagic species that lives in freshwater. Just pouring the southern coast of the Marmara Sea in Turkey Nilufer Stream, Kocaçay Ulubat Lake, Lake Manyas, Tea Susurluk, Han River, it is distributed in streams and lakes as Narlıçay. They are often found in fast-flowing waters.¹³ When the stomach contents analysis of B. oligolepis species was analyzed, it was observed that they consume mostly macro-invertebrates.^14,15 Squalius cii shows distribution in Europe, Asia and in Turkey has spilled rivers in the southern coast of the Marmara Sea. The substrate structure prefers habitats with pebbles, rocks and some silt. Most individuals are seen in isolated water pools left in the stream bed towards the end of summer.¹⁶ When the stomach contents analysis of S. cii species was analyzed, it was observed that they consume mostly macroinvertebrate species.^14,15 It was observed that native fish species around an aquaculture farm were fed with farm-derived feed when studies were conducted.^17–22 But no study has been found on whether this feed additive affects the height-weight relationship of indigenous fish species.

The aim of the study is to determine the effects of farm-derivated feed that entered to stream ecosystem on the native fish populations height-weight relations. On this scope, this study was carried out around a trout farm that located on Kocabas Stream in Canakkale, NW, Turkey.

The study was completed on Kocabaş Stream in the Biga Peninsula in northwestern Turkey (Figure 1). The sampling stations were selected from upstream (upper station) and the downstream (down station) of the trout farm that established next to the Kocabaş Stream. As a control station, a control zone was selected from situated on the branch of the stream without fish farm (Figure 2). Between August 2015 and July 2016, fish samples were collected by electro shocking for each region (excluding January) in the designated areas. The collected fish samples were first brought to the laboratory in cold chain and identified according to the "Turkey Freshwater Fish".²³

Figure 1 Map of the study area.

Figure 2 Schematicpresentation of the study area.

Each sample placed on the millimeter paper was photographed with a Nikon Coolpix S2800 model camera at the same height using a mechanism. Then weighed with a balance operating at±0,01g accuracy and and conventional morphometric measurements with 25 metric features were performed with compass (±1mm). Regression curves were obtained by using the equation below for each species caught from the stations to establish the relationship between height and weight. The value b in the equation defines the growth type of the fish and is influenced by habitat conditions.²⁴

Studies conducted in this area are considered to show allometric growth with a difference of 3, where the b value shows isometric growth when b is about 3. The measured b values differed from 3 (isometric growth) by Pauly t test according to the following formula.²⁵ 

Populations belong to B. oligolepis and S. cii were caught on Kocabaş Stream. Populations belong to both species were found in the upper and down stations, whereas only S. cii was found in the control station. When B. oligolepis samples captured from Kocabaş Stream were evaluated, b values were found to be 3.17 in the upper station and 3.31 in the down station (Figure 3). In the samples evaluated by Pauly t test, the value of b at the lower station is statistically different from 3 (P<0.05). It can be said that B. oligolepis individuals caught from the Kocabaş Stream exhibited an isometric growth in the upper station and a positive allometric growth in the down station.

Figure 3 Height-weight distribution of B. oligolepis populations caught from stations.

The b values of the S. cii samples taken from the Kocabaş Stream were found to be 3.41 in the upper station, 3.21 in the down station and 3.13 in the control station (Figure 4). The b value of the population in the down station is statistically different from 3 (P<0.05). It is possible to talk about an isometric growth for the individuals in the other stations and an allometric growth for the individuals in the down station.

Figure 4 Height-weight distribution of S. cii populations caught from stations.

A total of 125 specimens belonging to B. oligolepis and 131 specimens belonging to S. cii were determined. The effects of aquaculture on some parameters of growth of river fishes were evaluated with the findings of height-weight distributions. For B. oligolepis and S. cii, b value in down station was found to be different from 3. In the down station where the food sources and also the farm-derived feed are most abundant, the positive allometric growth exhibits that the species were indicative of the absence of food stress.

It has been reported that b values can vary interspecies, and that the same species can show variation according to gender, age, feeding style, habitat used and climatic changes.²⁶ The previous study of height-weight relationship with B. oligolepis populations was not found. It was determined that b value of the S. cii populations caught from Kocabaş stations was higher than the value found in the previous height-weight relation study.²⁷

It has been observed that the inedible feeds of the cultured fish are potential food sources for both natural fish species and other living beings (such as macro-organisms) in the environment, and that the growth rate of the individuals fed with these feeds is different from those fed the natural food sources.^28,29 The positive allometric growth seen in the individuals of the species caught in the river system affected by the aquaculture activities suggests that these individuals were fed by farm-based feed or groups feeding on this feed.

The author declares that there is no conflict of interest.

This study was a part of the “The effect of trout culture on some biological characteristics and trophic relations of freshwater fish in Biga Peninsula (Karamenderes and Kocabas Stream)” headed PhD thesis. The authors would like to acknowledge support by COMU‐ BAP (412 coded Project) and the Ministry of Forestry and Water Management, Nature Protection and National Park General Directorate, Çanakkale Regional District. We also thank İlker BAKAÇ for helping with field sampling. This study was completed with the permits COMÜ Animal Ethics Committee (30.07.2015/B.30.2.CAU.0.05.06‐050.04‐65), Ministry of Forestry and Water Management (02.01.2017/49978340‐499‐1621) and Ministry of Food, Agriculture and Livestock (06.10.2015/678525 65‐140.03.03‐2556).

1. Hall PO, Holby O, Kollberg S, et al. Chemical fluxes and mass balances in a marine fish cage farm. IV. Nitrogen. Marine Ecology Progress Series. 1992;89:81–91.
2. Machias A, Karakassis I, Labropoulou M, et al. Changes in Wild Fish Assemblages After The Establishment of a Fish Farming Zone in an Oligotrophic Marine Ecosystem. Estuarine, Coastal and Shelf Science. 2004;60(4):771–779.
3. Beveridge MCM, Phillips MJ, Macintosh DJ. Aquaculture and the Environment: The Supply of and Demand for Environmental Goods and Services by Asian Aquaculture and the Implications for Sustainability. Aquaculture Research. 1997;28(10):797–807.
4. Troell M, Norberg J. Modelling Output and Retention of Suspended Solids in an Integrated Salmon–Mussel culture. Ecological Modelling. 1998;110(1):65–77.
5. Naylor RL, Goldburg RJ, Primavera JH, et al. Effect of Aquaculture on World Fish Supplies. Nature. 2000;405:1017–1024.
6. Miller D, Semmens K. West Management in Aquaculture. West Virginia University Extension Service Publication No. AQ02–1. USA. 2002.
7. Merican ZO, Phillips MJ. Solid Waste Production from Rainbow Trout Salmo gairdneri Cage Culture. Aquaculture and Fisheries Management. 1985;16(1):55–69.
8. Grey J, Kelly A, Ward S, et al. Seasonal Changes in the Stable Isotope Values of Lake Dwelling Chironomid Larvae in Relation to Feeding and Life Cycle Variability. Freshwater Biology. 2004;49(6):681–689.
9. Blanchfield PJ, Tate LS, Podemski CL. Survival and Behaviour of Rainbow Trout (Oncorhynchus mykiss) Released from an Experimental Aquaculture Operation. Canadian Journal of Fisheries and Aquatic Sciences. 2009;66(11):1976–1988.
10. Kullman MA, Kidd KA, Podemski CL, et al. Assimilation of Freshwater Salmonid Aquaculture Waste by Native Aquatic Biota. Canadian Journal of Fisheries and Aquatic Sciences. 2009;66(11):1965–1975.
11. Pearson TH, Rosenberg R. Macrobenthic Succession in Relation to Organic Enrichment and Pollution of Marine Environment. Oceanography and Marine Biology. An Annual Review. 1978;16:229–311.
12. Arzul G, Rosenthal H, Clement A, et al. Aquaculture in Southern America and Ecological Interactions with Noxious Phytoplankton in Aquaculture. In: IFREMER, editor. Environment and Marine Phytoplankton. Actes colloque, France. 2001;7–28.
13. Turan D, Kottelat M, Ekmekçi FG. Barbus niluferensis, A New species of Barbel (Teleostei: Cyprinidae) from Nilüfer River, Turkey, with Re–description of B. oligolepis. Zootaxa. 2009;1981(1): 15–28.
14. Özdilek ŞY, Jones RI. The Diet Composition and Trophic Position of Introduced Prussian Carp Carassius gibelio (Bloch, 1782) and Native Fish Species in a Turkish River. Turkish Journal of Fisheries and Aquatic Sciences. 2014;14(3):769–776.
15. Özdilek ŞY. Seasonal and Ontogenetic Diet Shift of Two Sympatric Cyprinid Fish Species from the Temperate Karamenderes River, Çanakkale, Turkey. Turkish Journal of Zoology. 2017;41(1):67–81.
16. Stoumboudi MT, Kottelat M, Barbieri R. The Fishes of the Inland Waters of Lesbos Island, Greece. Ichthyological Exploration of Freshwaters. 2006;17(2):129–146.
17. Serrano R, Blanes MA, Orero L. Stable Isotope Determination in Wild and Farmed Gilthead Sea Bream (Sparus aurata) Tissues from the Western Mediterranean. Chemosphere. 2007;69(7):1075–1080.
18. Mao Z, Gu X, Zeng Q. Food Sources and Trophic Relationships of Three Decapod Crustaceans: Insights from Gut Contents and Stable Isotope Analyses. Aquaculture Research. 2016;47(9):2888–2898.
19. Gutmann Roberts C, Bašić T, Amat Trigo F, et al. Trophic Consequences for Riverine Cyprinid Fishes of Angler Subsidies Based on Marine‐Derived Nutrients. Freshwater Biology. 2017;62(5):894–905.
20. Wellman S, Kidd KA, Podemski CL, et al. Incorporation of Wastes by Native Species During and After an Experimental Aquaculture Operation. Freshwater Science. 2017;36(2):387–401.
21. Gürkan SE. Alabalık yetiştiriciliğinin Biga Yarımadasındaki (Karamenderes ve Kocabaş Çayları) akarsu balıklarının bazı biyolojik özellikleri ve trofik ilişkileri üzerine etkisi. Doktora tezi. Çanakkale Onsekiz Mart Üniversitesi. 2018.216 s.
22. Geldiay R, Balık S. Turkish Freshwater Fishes. 6th edn. İzmir: Ege University Press. 1988; 644 p.
23. Ricker WE. Computation and Interpretation of Biological Statistics of Fish Populations. Journal of Fisheries Research Board of Canada. 1975;191: 382.
24. Pauly D. Fish Population Dynamics in Tropical Water: A Manual for Use with Programmable Calculators. ICLARM Studies and Reviews 8. 1984; 8: 325p.
25. Çetinkaya O. Balıkçılık Biyolojisi ve Populasyon Dinamiği Ders Notları. Akdeniz Üniversitesi Eğirdir Su Ürünleri Meslek Yüksek Okulu. Isparta. 1989;1–65.
26. İlhan A, Sarı HM, Saygı H, et al. Length–weight Relationships of Freshwater Fishes in the Biga Peninsula (Northwestern Anatolia, Turkey). Journal of Applied Ichthyology. 2012;28(5):857–858.
27. Thodesen J, Grisdale–Helland B, Helland SJ, et al. Feed Intake, Growth and Feed Utilization of Offspring from Wild and Selected Atlantic Salmon (Salmo salar). Aquaculture. 1999;180(3–4):237–246.
28. Jonsson, N, Jonsson B, Hansen LP. The Marine Survival and Growth of Wild and Hatchery‐reared Atlantic Salmon. Journal of Applied Ecology. 2003;40(5):900–911.
29. Kousoulaki K, Olsen HJ, Albrektsen S, et al. High Growth Rates in Atlantic Salmon (Salmo salar L.) Fed 7.5% Fish Meal in the Diet. Micro–, Ultra–and Nano–filtration of Stickwater and Effects of Different Fractions and Compounds on Pellet Quality and Fish Performance. Aquaculture. 2012;338:134–146.