Suat DİKEL (1) M.Vedat ALEV (1) Gül.A.KİRİŞ (1) Metin KUMLU (1)

Journal of the Faculty of Agriculture Vol:17 No:2 2002 p 93 98. Growth And Yield Of Two Tilapia Species Tilapia zillii and Tilapia rendalli Raised In Floating Cages In Seyhan Dam Lake Suat DİKEL (1) M.Vedat ALEV (1) Gül.A.KİRİŞ (1) Metin KUMLU (1) Abstract Tilapia zillii and Tilapia rendalli juveniles were reared in two periods (15 days and 75 days) in cages in Seyhan Dam Lake. T.zillii and T.rendalli (1.00±0.59 and 0.84±0.46 g) juveniles were stocked at 375 fish m -3 in hapa cages and were reached to 4.63±2.49 and 3.83±1.84 g weights respectively after a period of 15 days. In the second culture period fry were stocked at 30 fish m -3 in 95-m 3 floating cages. According to final results, T.zillii has a higher daily weight gain (1.783 vs. 1.508 g day -1 ) (P> 0.05), larger final weight (161.54±27.68 vs. 136.60±21.12 g) (P< 0.05) and a lower feed conversion ratio (1.122 vs.1.349) than T.rendalli (P> 0.05). Final total net weight of T.zillii was greater (4.690 kg m -3 ) than T.rendalli (3.917 kg m -3 ). It has been demonstrated that T.zillii has a greater growth performance than T.rendalli in floating cage culture at commercial-scale in Seyhan Dam Lake in summer season. Key words: Tilapia, cage culture, Seyhan Dam Lake İki Farklı Tilapya Türü Olan Tilapia zillii ve Tilapia rendalli nin Seyhan Baraj Gölünde Kafes Koşullarında Yetiştiriciliği Özet Denemede Tilapia zillii ve Tilapia rendalli juvenilleri Seyhan Baraj Gölüne yerleştirilmiş yüzer ağ kafeslere stoklanmıştır. Denemenin ilk bölümünde "Hapa" tipi kafeslere 375 adet/m 3 oranında stoklanan (1.00±0.59 and 0.84±0.46 g) juveniller 15 gün süreyle beslendikten sonra 4.63±2.49 ve 3.83±1.84 g ortalama canlı ağırlığa ulaştıklarında denemenin ikinci bölümünü oluşturan esas semirtme kafeslerine (12mm lik ağ gözlü 95 m 3 hacimli ) 30 adet/m 3 oranında stoklanmıştır. Denemede %28 Ham protein içeren ticari bir yemle beslenen T.zillii ve T.rendalli yavruları 90. Gün sonunda 161.54±27.68 ve 136.60±21.12 g canlı ağırlığa (P<0,05), 1,783 ve 1.508 g/gün günlük canlı ağırlık artışına (P>0,05), 1,122 ve 1,349 Yem değerlendirme oranına (P>0,05) ve 4,690 kg/m 3 ve 3,917 kg/m 3 ürün değerine ulaşmışlardır. Deneme sonunda T.zillii 'nin Seyhan Baraj Gölü yaz ayları koşullarında T.rendalli'den daha iyi besi performansı gösterdiği tespit edilmiştir. Ayrıca Seyhan Baraj Gölünde kafes sistemlerinde ticari boyutta tilapya yetiştiriciliği başarıyla uygulanmıştır. Anahtar Kelimeler: Tilapya, Kafes Kültürü, Seyhan Baraj Gölü Introduction Tilapia culture continues to expand worldwide (Suresh, 2000). Cultured tilapia production in 2001 (nearly 1 million mt.) increased percent from that in 1996 (Roderick 2001). In Turkey small-scale pond farming and experimental cage-culture of tilapias have been practised for some years. Aquaculture is rapidly expanding in Turkey (New, 1999), but there is no data concerning the production of tilapia in the country. In temperate or sub-tropical regions, (as in coast of Mediterranean in Turkey) production of tropical animals such as tilapia is limited to a single seasonal crop. Under these conditions it becomes increasingly important to maximise production per unit (kg/ha) (Tidwell et al 2000). The primary problem for the culture of tilapia in sub-tropics is the limited growing season during which animals cannot be grown to marketable size. Monosex culture is the most recommended methods for increasing marketable size of tilapia. (1) Manual selection of male tilapia based on differences between the male and female genital papilla; (2) hybridisation of two species of tilapia that yield 0% male offspring; and (3) hormone induced sex inversion (Guerrero, 1982). No monosex culture system guarantees the complete elimination of tilapia reproduction from grow-out ponds. Female tilapia are commonly mistaken for manual separation, especially when less than 30 g fish are selected (Mires 1969; Popma et al 1984). All-male (1) Çukurova Üniversitesi Su Ürünleri Fakültesi

hybrids can be produced pure strains selected tilapia species. However, maintenance of pure genetic broodstocks has proven difficult (Mires,1977; Lovshin, 1982). Genetically impure strains yield hybrids with a low percentage of females that, upon reaching sexual maturity, can spawn with the fertile hybrids. Production of 0% males using hormone-induced sex inversion is rarely accomplished. Although the steroid is eliminated during the grow-out period, healthconscious consumers may resist purchasing tilapia treated with chemical additives (Lovshin et al 1990 b). For these reasons so many authors claimed that culturing the tilapia in floating cages could eliminate these problems. Due to their tolerance to crowding and poor water quality, tilapias are well suited to cage culture (Masser, 1997). Especially phytophagous tilapia species (T.rendalli, O.niloticus) are preferred for extensive and semiintensive cage culture (Mires, 1995). In cage aquaculture, fouling is traditionally considered to be a problem resulting in decreased water flow and oxygen supply (Lovegrove,1979). Most of tilapias are able to use phytoplankton as well as peryphyton (Dempster et al 1993). Fish grazing activity can keep fouling at low levels. This property of tilapias has been considered as a positive effect of increased water flow in cages (Norberg, 1999). In the present study two tilapia species Tilapia rendalli and Tilapia zillii were cultured in floating cages under semi-intensive culture condition in the Seyhan Dam Lake. The aim of the study was to compare growth performances of two commercially important tilapia species. Materials and Methods The experiment was conducted in two phases at the research station of Faculty of Fisheries, University of Cukurova in the Seyhan Dam Lake. The Lake which study carried out is situated on Northern of Adana in Mediterranean region in Turkey. Lake surface area is 6782 ha and there is no aquaculture plant landed. There may be potential for aquaculture development in Seyhan Dam Lake, perhaps even on a relatively commercial scale, also when environmental considerations are taken into account. In the first phase the cages used in the experiment were 2x2x2 m with rope frames covered with 3 mm mesh nylon net. 5x5x3.8 m in dimensions with metal frames covered with 12 mm mesh nylon nets were used during the second phase. Tilapia zillii and Tilapia rendalli juveniles with a mean weight of 1.00± 0.59 and 0.84 ± 0.46 g were stocked at 375 fish m -3 in cages during the first phase of the research. Following the first phase, the fingerlings were stocked at 30 fish m -3 (Table 1). Fish were fed commercial floating pellets (28% crude protein, PINAR YEM A.Ş.) at 9. 00 and 17. 00 h. everyday except sampling days. Feeding rates were 3%, 2,5% and 2% body weight per day (%BWD.) during the first, second and third months respectively. The feeding rate was adjusted biweekly based on sample weight and mortality of fish. Average weights of tilapia were determined biweekly by bulk weighing 5% of the groups. Temperature and dissolved oxygen were measured at 9. 00 h. with an oxygen meter. In this research, total harvest and growth performance of two the tilapia species (Tilapia zillii and Tilapia rendalli) were determined and compared with each other. Data were analysed statistically by analyses of variance (ANOVA, α = 0.05). The analysis was done using SPSS statistical package.

Table 1 Growth performance of T.zillii and T.rendalli juveniles stocked 8 m 3 hapa cages at 375 fish m -3 during the first 15 day grow-out period. Performance measures Tilapia zillii Tilapia rendalli Stocking Total weight (kg per cage) 3.00 2.52 Mean weight (g per fish) 1.00±0.59 0.84±0.46 Harvest Total weight (kg per cage) 13.334.858 Mean weight (g per fish) 4.63±2.49 3.83±1.84 Weight gain Total weight (kg per cage).454 8.476 Mean weight (g per fish) 3.63 2.99 Daily weight gain (g per fish day -1 ) 0.242 0.199 Net yield (kg m -3 ) 1.306 1.059 FCR 1.47 1.79 Survival (%) 96 94.5 Table 2 Growth performance of T.zillii and T.rendalli fry stocked 95 m 3 cages at 30 fish m -3 during the 75 day grow-out period. Performance measures Tilapia zillii Tilapia rendalli Stocking Total weight (kg per cage) 13.334.858 Mean weight (g per fish) 4.63 ± 2.49 3.83 ± 1.84 Harvest Total weight (kg per cage) 458.773 382.889 Mean weight (g per fish) 161.54 ± 27.68 a 136.60 ± 21.12 b Weight gain Total weight (kg per cage) 445.624 372.154 Mean weight (g per fish) 156.91 132.75 Daily weight gain (g per fish day -1 ) 2.092 1.770 Net yield (kg m -3 ) 4.690 3.917 FCR 1.055 1.216 Daily weight gain (for 90 days) 1.783 ± 1.049 a 1.508± 0.92 a (g per fish day -1 ) Overall FCR (for 90 days) 1.122 ± 0.19 a 1.349 ± 0.28 a Survival (%) (for 90 days) 94.66 a 93.43 a Mean Values with different superscript letters in the same row were significantly different (P<0.05). Results During the first grow-out period, T.zillii and T.rendalli mean weight gain increased 4.63±2.49 g to 1.00±0.59 g and 3.83±1.84 g to 0.84±0.46 g per fish. Gross yield of T.zillii and T.rendalli were determined as 458.773 kg and 382.889 kg per cage with an individual mean weight of 161.54±27.68 and 136.60±21.12 g (P<.0.05). Daily weight gain (g per fish day -1 ) of T.zillii (1.783) was higher than the T rendalli

(1.508)( for 90 days) (P> 0.05). (Table2 and Fig.3). According to final results, net yield of T.zillii (4.690 kg m -3 ) was greater than T.rendalli (3.917 kg m -3 ). Feed conversion ratio (for 90 days) of T.zillii (1.122) was lower than T.rendalli (1.349) (P>0.05) (Table 2 and Fig.2). Survival rates of T.zillii and T.rendalli were found 94.66%, 93.43% respectively after a period of 90-days. Water quality parameters monitored were not significantly different (P>00.5) between cages. Dissolved oxygen and water temperatures throughout the experimental period ranged from 3.5 to 7.8 mg l -1 and 22.0 to 31 0 C. WEIGHT GAIN (g) Weight (g) 180 160 140 120 0 80 60 40 20 0 T.rendalli T.zilli JUL 08 22 Feeding Period Figure 1. Growth Performance of T.zillii and T.rendalli reared in cages FEED CONVERSION RATIO FCR 2 1,8 1,6 1,4 1,2 1 0,8 0,6 0,4 0,2 0 T.rendalli T.zilli JUL 08 22 Feeding Period Figure 2. Feed Conversion Ratios of T.zillii and T.rendalli during the 90-day feeding period

DAILY WEIGHT GAIN (g/day) 3,5 3 Growth (g/day) 2,5 2 1,5 1 T.rendalli T.zilli 0,5 0 JUL 08 22 Feeding Period Figure 3. Daily Weight Gain (g/day) of T.zillii and T.rendalli during the 90-day feeding period. Discussion T.zillii which cultured in cage systems reached the desirable market size (>150 g) rapidly with mean weight gains of 1.783 ± 1.049 g per fish day -1. Weight gain of T.zillii was greater than those reported previously (0.705 g to 1.15 g per fish day -1 ) for semi intensive culture of T.zillii in ponds (Haller, 1974., Sarıhan et al 1988.,Polat et al. 1995) Growth rates of T.rendalli are lower than the many commercial tilapia species (O.nilotcus, O.aureus etc.) in one growing season. T. rendalli reaches 0-150 g/yr. (Balarin and Haller 1982). In present study T.rendalli reached the 136.60±21.12 g the final weight in only 90 days. O.nilotcus and O.aureus which most popular culture species in the world reach to 130-145 g final weight in semi intensive pond condition in one growing season (Polat et al 1994., Dikel,1995). In recent study demonstrated that weight gain of T.zillii and T.rendalli which cultured in cages were relatively higher than the many commercial tilapia species which culture in ponds. FCR. of T.zillii was lower than T.rendalli and both of their FCR were found that results are appropriate in aquaculture. Net yield of T.zillii and T.rendalli from present experiment were lower than those (12.86 to 26 kg m 3 ) reported by Haller, (1974), and Patino, (1976) from cages. The results showed that the growth performance of T.zillii is higher than the T.rendalli. T.zillii can be considered as a suitable species for intensive cage culture in Seyhan Dam Lake. References Balarin,J.D., and Haller,R.D.,1982 Intensive Culture of Tilapia in Tanks,Raceways andcages. In Muir,J.F., Roberts, R.J., (Editors) Recent Advances in Aquaculture. Croom Helm London.265-357. Dempster,P., Beveridge,M.C.M., Baird,D,J., 1993. Herbivory in Tilapia Oreochromis niloticus a comparison of feeding rates on phytoplankton and periphyton. Journal of Fish Biology.; 43: 385 392. Dikel,S.,1995. İki Tilapia türü olan Oreochromis aureus ve Oreochromis niloticus ve bunların Melezlerinin Çukurovada havuz koşullarında yetiştirilmesi, çeşitli büyüme performansları ile karkas ve besin

özelliklerinin karşılaştırılması. Doktora Tezi..Ü. Fen Bil. Enst. Adana. 92, Gurrero,R.D. 1982.Control of Tilapia Reproduction, In R.S.U.Pullin and R.H.Love McCannell (Editors),The Biology and Culture of Tilapias. ICLARM Conference Proceedings. 309-316. Haller,R.D., 1974. Rehabilitation of a Limestone Quarry. Report of an Environmental Experiment. Publication by Bamburi Portland Cement Co.Ltd. Mombasa, Kenya.1-32.Lovegrove, T.,1979. Control of Fouling in Farm Cages. Fish Farming International. 6:35-37. Lovegrove,T.,1979.Control of fouling in farm cages. Fish Farming International 6, 35-37. Lovshin,L.L., 1982. Tilapia Hybridization. In R.S.U.Pullin and R.H.Love McCannell (Editors), The Biology and Culture of Tilapias. ICLARM Conference proceedings. 279-308. Lovshin,L.L., Da Silva,A.B., Carniero- Sorbinho, A., Melo,F.R. 1990 b. Effects of O.niloticus females on the growth and yield of male hybrids (O.niloticus famele x O.hornorum male) cultured in earthen ponds. Aquaculture.;88: 55-60. Masser.,M.P.1997. Cage Culture: species suitable for cage culture. Southern Regional Aquaculture Center (SRAC) Publication No. 163. Southern Regional Aquaculture Center, Stonesville, Missisippi, USA. Mires,D., 1969. Mixed Culture of Tilapia with Carp and Grey Mullet in Ein Hemifratz Fish Ponds. Bamidgeh., 21 (1):-32. Mires,D., 1977. Theoretical and practical aspects of Reproduction of All-male Tilapia Hybrids. 29 (3): 94-1.Mires.,D.,2001. The Tilapias. Chapter 7. Selected Articles on Aquaculture in Israel Shefayim 90-1. Mires,D.,1995.The Tilapias. Selected Articles on Aquaculture in Israel.MASHAV.p.90-1. New,B.M.:1999. Global Aquaculture; Current Trends and Challenges for the 21 st Century. World Aquaculture Society Magazine.; 30 (1): 8-16 Norberg,J., 1999. Periphyton fouling as a marginal energy source in tropical tilapia cage farming. Aquaculture Research. 30: 427-437. Patino,R.A.,1976. Cultivo experimental de peces en Estanques (in English). J.New Alchemists, 3:86-90. Polat,A., Yanar,M., Tekelioğlu,N.,Gökçe, 1994. M., Farklı iki tilapya türü (Oreochromis aureus ve Oreochromis niloticus) un Çukurova koşullarında Ürün Verimliliği Üzerine Etkileri. Su Ürünleri Sempozyumu, İzmir. 237-248 Polat,A.,Dikel,S.,Tekelioğlu,N.1995.Tilapyalardan (T.zillii) Erken Dönemde Döl Alınması ve Bunun Yetiştiricilik Üzerine Etkileri. Ç.Ü.Z.F.Dergisi (1):121-131 Popma,T.J.,Ross,F.E.,Nerrie,B.L.BowmanJ.R., 1984. Development of commercial farming of tilapia in Jamaica 1979-1983. International Center for Aquaculture, Albama Agricultural Experiment Station, Auburn University, Auburn,A.L.Research and Development Series,1984; 31:18. Roderick,E. 2001: Tilapia 2001- First global conference. Fish Farmer International file, ;15(4) : 24-. Sarıhan.E.,Tekelioğlu,N.,Polat,A.,1988. Farklı Stoklama Oranlarının Tatlısu çipurası (O.niloticus) ların gelişme ve gelişme performanslarının karşılaştırılması. XII. Ulusal Biyoloji Kongresi6-8 Temmuz Edirne 30-35, Suresh,A.V. 2000 Tilapia Update 1999. World Aquaculture Society Magazine. 31(4): 16-20. Tidewell,H.J.,Coyle,S.D.,Vanarnum,A. Weibel,C. 2000. Growth, Survival, and Body Composition of Cage-Cultured Nile Tilapia Oreochromis niloticus Fed Pelleted and Unpelleted Distillers Grains with Freshwater Prawn Macrobrachium rosembergii. World Aquaculture Society. 31(4) :627-631.