Oscillator frequency effects on death rate and physiological status of Sepiella japonica

Enhancement and releasing are significant for the restoration of Sepiella japonica. To increase the survival rate of S. japonica dring transportation of proliferation and releasing, the effects of different oscillation frequencies (0, 60, 100, 120, 140 and 160 r/min) on death rate, the contents of lactate and glycogen, as well as enzyme activity of adult S. japonica were studied. The results showed that the death rate increased with the frequency increases in other groups, except for a slight decrease at the frequency of 160 r/min. The highest death rate was 97.1% at the frequencies of 120 and 160 r/min, and it was obviously higher than that at the frequencies of 0, 60 and 100 r/min (P<0.05). The death time mainly range from 4-8 h after oscillation and the lower the frequency, the later death time appeared. Except for some statistics fluctuations in a few groups, it basically followed the trend that glycogen content in the two tissues decreased with the increase of frequency, while the lactate content increased. Compared to the treatment group, the experimental group at the frequency of 140 r/min had a significant difference in lactate and glycogen contents(P<0.05). Except for the experimental group at the frequency of 60 r/min, the activity of alanine transaminase (ALT) and glutamic-oxalacetic transaminase (GOT) in pancreas tissues decreased, and the activity of superoxide dismutase (SOD) increased with the increase of frequency. Compared to other experimental groups, these three enzymes at the groups of 120, 140 and 160 r/min respectively, had a significant difference (P<0.05). The activity of alkaline phosphatase (ALP) increased with the increase of frequency, the groups of 140 r/min and 160 r/min had a significant difference compared with other groups (P<0.05). The death rate of squid was positively correlated with SOD, lactate content and ALP, and negatively correlated with muscle glycogen content, GOT, ALT and digestive gland glycogen content (P<0.01). In conclusion, during the transport of S. japonica, energy exhaustion and hepatopancreas damage could be the major reasons of high death rate. In order to solve this problem, the oscillation frequency during transportation should be below 100 r/min and the transportation time under 3 hours and should avoid strong waggle.