조피볼락과 참전복의 장거리 활어수송 조건 구명 및 건강도 평가

Abstract

Traditional live fish exports rely on air transport that is expensive shipping cost (14,000 won/kg), the restriction of species (olive flounder). But maritime live fish container can transport various species (rockfish, abalone, mullet, etc) and the advantage of saving shipping cost (round 6,000 won/kg, one-way 4,000 won/kg). So investigated to know optimum temperature and salinity for long-distance transportation by live fish container. 1. Health Assessment of Rockfish on Different Temperature and Salinity The suitable temperature and salinity condition for the long-distance transportation for the rockfish were investigated by assessing survival rate, metabolism, hematological characteristic, immunity (hemocyte population and hemocyte mortality), and histological change. Further, it was also investigated if interaction of temperature and salinity affect the characteristics for rockfish. Survival Rate and Metabolism Changes There was no weight reduction and all the experimental groups showed survival rates of 100%. Daily oxygen consumption rhythm was decreased during nights and increased during days. Average oxygen consumption showed decreasing tendency as the temperature and salinity were decreased. Ammonia excretion was significantly increased as temperature and salinity were decreased. Hematological Characteristics Hematocrit and hemoglobin were no particular trend. Glucose was highest in 34 psu (4℃), 18 psu (4-6℃) and 10 psu (4-8℃). Cortisol was highest in 4℃, decreasing significantly as the salinity was decreased. AST and ALT were increased as temperature was decreased under the salinity lower than 26 psu. Ions and osmolality were decreasing as salinity became lower. Immunity (Hemocyte Population and Hemocyte Mortality) Percentage of the blast-like cell was significantly decreased as salinity was decreased. Percentage of hyalinocyte was not affected by the salinity. But granulocyte was significantly decreased as temperature and salinity were decreased, which indicated that granulocyte was significantly affected by the temperature and salinity. The ratio of the live cell was 99.0-99.6% in all the experimental groups. hemocyte mortality was significantly changed by temperature and salinity, although the mortality was less than 1%. Histological Changes The mucous cell of rockfish which was exposed to temperature at 4℃ under the 34 psu. However, histological changes were observed in the skin and gill of the rockfish exposed to salinity lower than 18 psu under all the temperature conditions, with larger changes at 4℃, which was the lowest temperature. Further, nucleus deformation and uniformity in the cytoplasm were also observed. 2. Health Assessment of Abalone on Different Temperature and Salinity The suitable temperature and salinity condition for the long-distance transportation of abalone were investigated by examining hypertrophy, metabolism, hemolymph characteristic, antioxidant enzymes, immunity (hemocyte population and Hemocyte Mortality), body composition, and histological changes. Further, the effect of the interaction between temperature and salinity on the characteristics of abalone were also investigated. Survival Rate and Flash Weight Index There are 96-100% survival rate when temperature was higher than 8℃. However, the survival rate was decreased as salinity was decreased under the temperature lower than 6℃. At 34 psu, 100% dead was observed only at 4℃ but When salinity lower than the natural sea water 100% dead was observed at 6℃. Decreases of weight and flash weight index were not observed. Metabolism Changes At 26 psu, oxygen consumption during light period was higher than dark period. The average oxygen consumption was significantly decreased as temperature was decrease. Ammonia excretion rate was in an increasing tendency as temperature was decreased under all the salinities. The O:N ratio was the highest at 8-10℃ and the lowest O:N ratio at 4℃. Hematological Characteristics Glucose was highest at 4℃ under all the salinities. NH3 was highest at 4℃ and increased as temperature was decreased. AST and ALT were highest in 4℃ under all the salinities. Ions and osmolality were decreased as the salinity was decreased. SOD activity was highest at 4, 6℃ under 30, 34 psu, but it became below the threshold level 0.025 U/mL at 4℃ under 26 psu. Gluthathione was highest at 4℃, it was significantly increased as salinity was decrease. Immunity (Hemocyte Population and Hemocyte Mortality) THC at 4 and 6℃ were significantly lower than 8, 10℃, and it was significantly increased as salinity was decrease. Hemocyte population was categorized into blast-like cell and hyalinocyte. Blast-like cell was increased when temperature was decreased. Hyalinocyte was significantly decreased as temperature and salinity were decreased. Live cell was significantly decreased as temperature and salinity were decreased. Apoptotic cell and necrotic cell were significantly increased as temperature and salinity were decreased. Free Amino Acid (FAA) Composition Aspartic acid, threonine, serine, and glycine, were increased as temperature was decreased. Taurine, aspartic acid, glutamic acid, and arginine were significantly increased as salinity was decreased, while glycine, alanine, methionine, tyrosine, and histidine were decreased as salinity was decreased. Taurine was significantly increased as temperature and salinity were decreased. Glycine was significantly decreased as temperature and salinity were decreased. Histological changes In the epidermal layer and muscles of the abalone foot exposed to temperature at 8℃, 6℃, and 4℃ under 34 psu, no histological changes. The thickness of the epidermal layer of the abalone foot was decreased under at 6℃ and 4℃ with the salinity at 30 psu on the 14th day. While decreases in the thickness of epidermal layer and basophilic cells were observed from the abalone feet exposed to at 26 psu from the 7th day. Further, epidermal layer was fallen along with decreases in the thickness as temperature was decreased from the abalone after elapse of 14 days. Besides, density of the muscle bundle was decreased, especially for the abalone exposed to 4℃, huge hemolymph sinus was observed. 3. Assessment of Health during Combined Transportation of Rockfish and Abalone The survival rate, hematological characteristics, immunity (hemocyte population and hemocyte motality), and histological changes were investigated in order to assess health of rockfishes and abalones when these were transported in combination. Survival Rate The survival rate of rockfish was 96.8% and 98.7% for the experimental group and control, respectively. In case of abalone, the survival rate was 100% until the 5th day and it was high more than 99% till the end of experiment which was not different from control. Hematological (Hemolymph) Characteristics [Rockfish] The range of Ht an Hb were not significantly different from control. Glucose was significantly higher in the experimental group after experiment starting, but it was decreased with elapse of time. Cortisol was higher by around 3 times in the experimental group, but decreased with elapse of time which was not significantly different from control. AST and ALT were also not significantly different after recovery. NH3 was, though higher by around 3 times in the experimental group until 14th day, after recovery, threre was not significantly different from the control. Plasma ions and osmolality were not much different from the control during the experiment. [Abalone] Glucose did not show a significant difference. TCHO was did not show significant difference after recovery. AST and ALT were not significantly different between experimental group and control. TP was 1.1±0.2 g/dL in the control on the 14th day as compared with experimental groups. However, except that, there was no significant difference. NH3 was abruptly increased till the 14th day in the experimental groups showing around 36 times higher as compared with control, but this value was decreased to the initial level after recovery. SOD and gluthathione did not show significant difference between experimental group and control. Hemolymph ions and osmolality were similar with elapse of time, and did not show significant difference. Immunity (Hemocyte Population and Hemocyte Mortality) [Rockfish] Blast-like cell and hyalinocyte were increased on the 7th day of experiment, followed by decreases with no significant difference. Granulocyte was decreased on the 7th day in both the experimental group and control, followed by increases again from the 14th day, and showed a higher value as 42.7% in the experimental group after recovery. Live cell was higher in the experimental group as well as control more than 97% with no significant difference. The ratio between initial apoptotic cell, and necrotic cell was similar in both experimental group and control during experimental period. [Abalone] Blast like cell was higher in the control after recovery, while hyalinocyte was significantly higher in the experimental group than in control. Live cell was not significantly different after 14th day. Apoptotic cell was not show significant difference for each other after 14th day. Necrotic cell at the final stage of experiment was not significantly different throughout the experimental period. Histological Analysis In case of rockfish, many mucous cells were found from the epidermal layers after 14 days. While, in the gill, various histological changes such as hypertrophy of epithelial cells, increases in chloride cells and mucous cell were observed. In case of abalone, the histological changes in the epidermal layer and muscle layer of the foot in the experimental group on the 7th day and 14th day of experiment were not prominent as compared with the initial experiment stage.