Comparison of individual rearing systems according to stocking density for octopus (Octopus vulgaris) grow-out in in-situ

Abstract

The purpose of this study is to evaluate the biological performances, survival and growth rates of the common octopus in individual rearing systems according to stocking density. The experiments were performed near Yeosu, Korea in the water depth (5-7 m) were used with an initial body wet weight of 486 ± 114 g. The cage models were made of polypropylene tube for the frames. The size of the cage models were 1100L × 460B × 500D mm, The three cages were used. The installation of eight each 1200L × 200D mm (density 10kg/㎥), 700L × 160D mm (density 30kg/㎥) and 350L × 130D mm (density 60kg/㎥) tube inside the cage. At this site, the water temperature ranged from 12.25 to 21.36℃, and salinity ranged from 30 to 32.79 psu, DO ranged from 5.08 to 9.28 mg/L, pH ranged from 7.8 to 8.13, respectively. Octopuses were fed a diet of frozen sardine (Sardinops melanostictus) and swimming crab (Portunus trituberculatus) (approximately 3-8% of their body weights). The results of the experiments were analysed with the statistical computer package SPSS ver. 21 from IBM.BR In experiment, the survival rates of octopus in density 10 kg/㎥ tube(75%) and 30 kg/㎥ tube(87.5%) were higher than those of density 60 kg/m3 tube(62.5%). The specific growth rate (SGR) of octopus in density 60 kg/m3 tube(0.24%/d-1) was slightly higher than those of density 10 kg/m3 tube(0.18%dSUP-1/SUP) and 30 kg/m3 tube(0.17%dSUP-1/SUP).