| In this study, we investigated the effects of low temperature anesthesia, low salinity anesthesia, different temperatures, different soaked time, cold storage on the soft-shell crab, Portunus pelagicus and the effects of temperature, time, salinity on Portunus pelagicus, spawning crab. All the results are as following:1. Under the conditions of salinity 30, pH 7.5-8.5 and temperature of 27℃-30℃, we put the Portunus pelagicus which just molted into the artificial seawater with different low temperature anesthesia and low salinity anesthesia, to test the effects of low temperature anesthesia, low salinity anesthesia on the soft-shell crab, Portunus pelagicus. The results are as following: The effect of low temperature anesthesia on the increase weight of soft shell crab Portunus pelagicus is little. And the anesthesia time shorter, the rate of the increase weight is smaller.anesthesia time, less than 7 min, the soft shell crab Portunus pelagicus rate of weight gain less than 2%, and more than 7 min, the soft shell crab Portunus pelagicus rate of weight gain between 2% -4%. Among them, the anesthesia time was 13 min, the anesthesia temperature 2℃, 4℃6℃, and when the soft shell crab Portunus pelagicus in the greater rate of weight gain, and no significant difference among the three (p> 0.05). Anesthesia time was 1 min, each temperature group were all alive. Anesthesia time was 4 min, the temperature of 0℃and the temperature began to decrease the survival rate of 2℃, anesthesia time was 7 min, only the temperature is 8℃soft shell crab all survived, and longer anesthesia time, the survival rate even lower. This shows that the temperature of cold anesthesia should be between 0 -6℃, anesthesia time was 7 min was more appropriate.Anesthesia group compared with the low-temperature, low salinity and anesthesia on the soft shell crab Portunus pelagicus greater impact on body weight, and lower salinity anesthesia, anesthesia time, the longer the soft shell crab Portunus pelagicus weight gain rate is higher. Which anesthesia salinity 0‰, anesthesia time 10 min, after anesthesia soft shell crab Portunus pelagicus weight gain rate of more than 30%.However, with lower salinity anesthesia, anesthesia time, the soft shell crab Portunus pelagicus lower survival rate. Anesthesia time was 1 min, each salinity group were all alive. Anesthesia time was 5 min, the salinity of 0‰and 3‰salinity the survival rate started to decrease anesthesia time was 10 min, only 12‰salinity, the soft shell crab all survived, and longer anesthesia time, the survival rate lower. So soft shell crab Portunus pelagicus during anesthesia salinity salinity 0‰, anesthesia time 10 min, more satisfactory results.2. Under the conditions of salinity 30, pH 7.5-8.5 and temperature of 27℃-30℃, we put the Portunus pelagicus which just molted into the artificial seawater with different temperatures, different soaked time, to test the effects of temperatures and soaked time on the soft-shell crab, Portunus pelagicus. The results show that the experimental temperature of 12℃, 10 min soaking time, the sea and experimental temperature 10℃, water soaking time 20 min both cases, the soft shell to keep the time, respectively (44.67±0.29) h and (42.50±5.20) h, each no significant difference between (p> 0.05), with other conditions, significant difference (p <0.05). Under low-temperature group soft shell crab Portunus pelagicus significant difference in survival; 14℃temperature group, 16℃and 18℃temperature set higher temperature group survival, the basic die, no significant difference between the respective (p> 0.05), and survival rate of the temperature difference between the other groups were significantly (p <0.05). At 8℃, the soft shell crab survival rate is 0, can not survive. 12℃temperature group and the other in survival between the temperature groups were significantly (p <0.05), test time, the average survival rate of 70%.3. Under the conditions of salinity 30, pH 7.5-8.5 and temperature of 27℃-30℃, we put the Portunus pelagicus which just molted into the -20℃environment, to test the effects of -20℃on the soft-shell crab, Portunus pelagicus. The results show that -20℃refrigerator for soft shell crab Portunus pelagicus weight greater impact. Storage bags can slow down the soft shell crab Portunus pelagicus weight loss rate, crisper storage bags out of the group is not about weight is no longer 40 d decreased, while crisper around the groups until 65 d body weight will remain unchanged, and soft shell crab Portunus pelagicus in the weight loss rate is significantly reduced.4. Under the conditions of salinity 30, pH 7.5-8.5 and temperature of 27℃-30℃, we put the Portunus pelagicus and its spawning crab into different temperatures, times and salinity, to test the effects of different temperatures, times and salinity on the Portunus pelagicus and its spawning crab. The results show that storage temperature on the survival rate of Portunus pelagicus a significant effect, 26 -30℃survival rates between the lowest, 24 h and all died within, 0 -5℃between, 6 -10℃when the second, 16 - the highest survival rate between 20℃.Berried crabs Portunus pelagicus to maintain normal temperature and crab Portunus pelagicus is different, 0 -5℃survival rates between the lowest, 12 h have all died within, 11 -15℃followed between, 21 -25℃between the highest survival rate.Anesthesia lower the temperature, Portunus pelagicus longer preservation time. Portunus pelagicus and berried crabs dry anesthetic prior to transport should be at 0-2℃ temperature between the more appropriate.When the anesthesia time was 1 min, 2 min, 6 min, 7 min, the lower the survival rate of Portunus pelagicus. This may be because 1 min, 2 min of anesthesia time is not enough, resulting in Portunus pelagicus in the foam box is not in anesthesia, thus a higher mortality rate. And 6 min, 7 min of the situation is the opposite. Portunus pelagicus anesthesia over high mortality. When the anesthesia time was 1 min, the berried crab Portunus pelagicus higher survival rate. This is normal crab Portunus pelagicus appears quite different. Anesthesia lower salinity, crab Portunus pelagicus and the preservation of spawning time is longer. Therefore, the water salinity 0‰anesthesia Portunus pelagicus better. |
PDF Full Text Request