Effect of stocking density on the growth performance and yield of Nile tilapia [Oreochromis niloticus(L., 1758)] in a cage culture system in Lake Kuriftu, Ethiopia

Abstract

This research was conducted to investigate the e¡ect of stocking density on the growth performance and yield of Oreochromis niloticus in cage culture in Lake Kuriftu. The treatments had stocking densities of 50 (50F), 100 (100F), 150 (150F), and 200 (200F) ¢sh per m À 3 . All treatments were in duplicate. Juveniles with an average weight of 45. 76 AE 0.25 g were stocked in the treatments. The ¢sh were fed a composite mixture of mill sweeping, cotton seed, and Bora food complex at 2% of their body weight twice per day using feeding trays for 150 days in powdered form. The growth performance of O. niloticus was density dependent. The ¢nal mean weight of O. niloticus ranged 147.76 AE 0.28^219.71 AE 1.42 g and the mean daily weight gain was 0.69 AE 0.01^1.15 AE 0.02 g day À 1 . Fish held in cages with lower density were heavier than the ones held at higher densities, and showed higher weight gain and daily weight gain. The most e¡ective stocking density, in terms of growth parameters, was 50 ¢sh m À 3 . The gross yield (4.52 0.55 kg cage À 1 ) showed a signi¢cant di¡erence with increasing stocking density (Po0.05). Moreover, the apparent food conversion ratio (2.48^7.22) was signi¢cantly a¡ected by stocking density (Po0.05). However, survival rate was not a¡ected by stocking density (P40.05). It can be concluded that the most e¡ective stocking densities were at 50 ¢shm À 3 cage for larger size ¢sh demand in a short period and 200 ¢sh m À 3 for higher gross production with supplementary feed.

Effects of stocking density on the cage culture of Korean rockfish (Sebastes schlegeli)

“…Stocking density can affect the survival rate in fish culture (Hargreaves et al, 1991;Wallat et al, 2004;Watanabe et al, 1990), influencing growth, survival, and behavioral interactions (Brown et al, 1992;Christiansen et al, 1992;Cruz and Ridha, 1991;Irwin et al, 1999). Similar results have been confirmed in freshwater fish (Gibtan et al, 2008;Yi et al, 1996;Zhu et al, 2011), and it is well-accepted that high-density stocking can cause reductions in growth rate and increases in mortality (Kincaid et al, 1976;Lee et al, 1996;McClain, 1995;Mills and McCloud, 1983;Morrissy, 1992). However, conflicting results have linked lowdensity culture with high mortality in rainbow trout (Oncorhynchus mykiss) and salmon (Refstie, 1977), and high-density culture with an increased growth rate, survival rate, and efficiency of food conversion in juvenile silver perch (Bidyanus bidyanus) and tilapia (Oreochromis spirulus) (Cruz and Ridha, 1991;Rowland et al, 2006;Watanabe et al, 1990).…”

Effects of inter- and intra-specific competition on the growth rates of juvenile European barbel Barbus barbus used in the stock enhancement of UK fisheries

“…Whilst aspects of these outputs concur with Taylor et al (2004), who concluded B. barbus growth in lentic fisheries was suppressed when the stock density of C. carpio exceeded 1000 kg ha −1 , they also demonstrate that growth will be similarly suppressed if the stocked species are T. tinca and B. barbus. This relationship between increasing stock abundance and reduced somatic growth is consistent with studies on other species completed primarily for aquaculture purposes, covering species such as brown trout Salmo trutta (Linnaeus, 1758) (Bohlin et al, 2002) and Nile tilapia Oreochromis niloticus (Linnaeus, 1758) (Gibtan et al, 2008).…”

Nursery I: The effect of stocking density on the performance of glass eels, Anguilla bicolor in the biofloc system

“…Similarly, stocking density of fingerlings of silver perch, Bidyanus bidyanus, stocked at 100 or 200 fish/m3 was not influenced survival. Several studies have also shown that the density have not significantly effect on survival of rainbow trout, Oncorhynchus mykiss [18], tambaqui, Colossoma macropomum [19] and Oreochromis niloticus [20]. Conversely with these study, it found in the endangered teleost species piabanha, Brycon insignis was higher survival at low stocking density [13].…”