The main objective of this investigation was to examine physiological changes occurring within the olive fl ounder, Paralichthys olivaceus, in the presence of continuous stress factors. The experiment gave continuous stress, and each stress step is as follows: water level reduction (S1), selection process (S2), confi nement (S3), air exposure (S4), transportation (S5), and storing in volume 0.5-t (S6) and 50.0-t (S7) rearing tanks for 24 h after transportation. The cortisol concentration showed a trend to continuously rise in response to consecutive stress from transportation from 7.4 ± 0.6 ng/ml in an experimental opening. The concentration showed the highest level, 25.3 ± 4.4 ng/ml, after confi nement stress. Glucose concentration in S3 and S4 were increased signifi cantly to 71.0 ± 13.0 and 78.7 ± 7.0 mg/ dl, respectively (P < 0.05). Lactic acid was increased signifi cantly from 0.5 ± 0.1 mM (S0) to 9.0 ± 1.2 mM (S4), but it did not recover until 24 h (7.0 ± 1.0 mM) after transportation (S6 and S7) (P < 0.05). Some contents displayed recovery within 24 h, but a longer time would be required for normal physical metabolism to resume after fi sh experienced stress. Therefore, it would be endangering the survival of this species if the transport were repeated within a 24-h period.Key words Paralichthys olivaceus · Consecutive stress · Transportation · Cortisol croaker, Nibea japonica and observed that the low stress response of the olive fl ounder was less likely to be affected by transport stress compared to the croaker during a 25-h period transport experiment. Olive fl ounders reacted with higher stress during the selection procedure employed before the transport than that after transport.The olive fl ounder is the number-one cultured fi sh produced in Korea, and thus the corresponding nursery and merchandise transport are involved in mass quantities. However, the lack of knowledge about physiological changes occurring in the olive fl ounder before and after transport has caused lethal consequences in large numbers. The olive fl ounders produced from Jeju Island and Namhae Sea are transported mostly via truck or ship for a long period of time, and temperature and dissolved oxygen concentration are controlled by applying blowing air, liquefi ed oxygen, and ice to increase the ratio of living fi sh.The necessary preliminary procedures during and after transport include water level reduction, capture, confi nement, air exposure, and long-distance travel, and this is one of the management items that the culture farm should consider. The selection procedure for transport functions as a stress-inducing factor to the fi sh, and the stress to the fi sh is composed of a combination of the factors of the procedures used during and after the transport. However, the producers of these fi sh execute this transport without fundamental knowledge concerning how the selection stress IchthyologicalResearch
A 12-wk experiment was conducted to examine the hematological changes, survival, and respiratory exchange in the olive flounder, Paralichthys olivaceus, during starvation. The growth, survival and respiratory exchange rates of the starved group were lower than those of the fed group during the experiment. Blood analysis, including hematocrit, hemoglobin, red blood cells, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, and mean corpuscular volume, did not differ significantly (p>0.05) between the fed and starved groups at the end of the experiment. There were no significant differences in plasma cortisol, glucose, Na + , Cl -, K + , or aspartate aminotransferase between the fed and starved groups (p>0.05). Alanine aminotransferase levels were higher in the starved group than in the fed group, whereas plasma osmolality was lower in the starved group than in the fed group. It was shown that starved fish had various problems after four weeks, which did not occur in the fed group. Long-term starvation is infrequent in aquaculture farms. However, starvation studies of this kind are very useful for a basic understanding of how physiological changes affect fish health, life expectancy, and growth.
The effects of nutritional conditions on alterations in condition factor, liver-somatic index, and hepatocyte ultrastructure in the olive flounder Paralichthys olivaceus were examined. Twelve weeks of starvation significantly decreased the condition factor and the liver-somatic index in the olive flounder. Hepatocytes underwent marked ultrastructural changes in response to 12 weeks of starvation. Compared to those of the initial control and fed group, the prominent features characterizing the hepatocytes of the starved group were: reduction in cell and nucleus size; apparent loss of nucleoli; condensation of chromatin; loss of stored glycogen; reduction of endoplasmic reticulum profile; increase in the number of electron-dense bodies containing large amounts of iron; and increased mitochondrial size. Results suggest that the histological changes caused by ultrastructural alterations in the hepatocytes can be used as alternative indicators to identify starvation in cultured P. olivaceus.
We investigated the in£uence of nutritional conditions on histological changes in melano-macrophage (MM) accumulation in the kidney caused by longterm starvation. These data were used to determine nutritional indices for olive £ounder, Paralichthys olivaceus (Temminck and Schlegel).Experimental groups were established: control, fed and starved. All ¢sh were fed daily with commercial feed at 1^3% of their total body weight for 2 weeks before the start of the experiment (initial control). The control group received feed at 1^3% of their total body weight and the fed group received feed ad libitum, while the starved group fasted throughout the experiment. Ten ¢sh were removed from the initial control at the start of the experiment and each of the three groups every 4 weeks during the 12 weeks of the experiment to examine to investigate kidney MM accumulation.Kidney MMs with dark brown pigment were randomly distributed in the kidneys of starved ¢sh, increasing rapidly after week 4, while deposition levels remained low throughout the experiment in the control and fed groups. These results suggest that catabolic tissue breakdown is a major factor contributing to the formation of pigments within MMs. These results suggest that the degree of MMs deposition in the kidney can be used as alternative indicators to identify starvation in wild and cultured olive £ounder.
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