In the grouper test this year, four common groupers in Taiwan (Epinephelus coioides, E. lanceolatus, E. fuscoguttatus, E. fuscoguttatus x E. lanceolatus) were tested the condition of the high temperature disaster. The results one showed that hybrid grouper survived the longest at 38°C. It died over 24 hours after experiment beginning, and other species of grouper died within 10 hours; at 37°C, hybrid grouper survived over 72 hours, but the death occured in three days after adversity, while other species died within 24 hours. After experiment 1 (35, 36°C), the results showed that the recovery phase of hybrid grouper was less than others; also all fish in the 35°C treatment started eating earlier than group 36°C. It showed that the water temperature over 36°C might cause more stress. Experiment 2 was treated with a short-term high water temperature (37°C), and there was no casulty. The recovery time was less than experiment 1. To against the high temperature disaster in future, shorten the time of water temperature over 37°C can effectively minimize the impact on grouper aquaculture.
In tilipia cold shock experiment, all the control fish died under the the condition of 9.5~7℃/18hrs but the experimental groups still showed the survival of 8~12 %. Duing the cooling process, experimental goups showed higher blood sugar concentrations(100~120 mg/dl) which were higher than control group((~80 mg/dl). In blood pH, control group showed higher pH(pH7.9) after cooling than experimental groups(pH7.3~7.5). In plasma protein concentration, the control group showed higher concentration(6.6 g/dl) than the experimental groups (5~5.9 g/dl). In the lipids contents of livers, the control showed higher
saturated fatty acids ratio(44.4 %) than the experimental groups(36.7~39.8%) after cooling. There were no obvious difference in the monoenes contents between the control and experimental groups. The experimental groups showed higher n6- and n3- HUFA contents(5.6~7.3% and 10.0~12.5%, respectively) than the control(4.4 % and 6.6 %, respectively).
White shrim is one of the important aquaculture species in China. However, in recent 20 years, it has been repeatedly infected by a variety of viruses, bacteria, fungi and other pathogens, making aquaculture difficult to succeed. In this experiment, white shrimps were fed with 0,1,2 and 3 % algae content white shrimps for 4 weeks (a total of 4 groups). During this period, white shrimps in each group were sampled every 3 days to analyze the blood immune response. In terms of osmotic pressure, white shrimps in 0 % group had high peaks on the 1st, 14th and 28th days, but the osmotic pressure value slowed down. In the feed with algae content of 1, 2 and 3 %, the value also fluctuates, and the vibration range is different. In terms of the total number of lymphatic blood cells, 0 % of the total number of lymphatic blood cells is the largest, and the algae feeding content is 1, 2 and 3 %. In the initial stage, the number of lymphatic blood cells tends to decrease. It seems that red plumed algae powder can reduce the number of lymphatic blood cells of white shrimp. In the Vibrio harveyi challenge test, after 8 hours of treatment, about 70 % of white shrimp in the 0 % group survived, and the survival rate of 80 % in the 2 % group was the highest, but there was no significant difference in statistics. After 24 hours, the survival rate of each group was about 10 ~ 15 %, and there was no significant difference. Adding red plumed algae powder to feed white shrimp could not increase the resistance to Vibrio harveyi.
Hard clam seeds has been stocked since May 2020, and experienced a cold event in the beginning of 2021. The use of multiple functional fishes to remove filamentous algae saves labor costs and reduces mortality. Till May 2021, the survival rate of the first harvest has reached more than 90%. In order to cope with the heavy rainfall, although deep water reservior and overflow drainage pipelines have been added for water discharge after heavy rains, monitoring the salinity of the water intake channels and the changes in the water level of the breeding ponds has shown that the salinity of the overall pond water and the water intake ditches has dropped significantly. Some clams died. After the second harvest on July 22, the total harvest rate was about 70 % (stocking 1,800,000 grains * 0.7 yield rate / 50 grains = 25,200 kilograms). Due to its location in reclaimed land, the bottom of the pond has too high permeability causing the salinity susceptible to heavy rain. It is recommended that larger clam seedlings can be stocked in the future to shorten the grow-out period and harvest earlier than the flood season to avoid the impact of heavy rainfall on the harvest rate.