Young-Jin Chang

Oxygen Consumption of Long-term Cultured Male Black porgy Acanthopagrus schlegelii in Freshwater by Water Temperature During the Reproductive Period

Oxygen consumption (OC) of male black porgy Acanthopagrus schlegelii reared in freshwater (BFW) and seawater (BSW) during the reproductive period was 165.4±11.0, 77.6±8.0 mg O2/kg/h at 15 , °C 186.2±13.1, 133.4±6.7 mg O2/kg/h at 20 and 267.9±19.1, 198.6±8.3 mg O °C 2/kg/h at 25 , respectively. °C During the non-reproductive period, it was shown as 174.0±7.0, 85.6±5.5 mg O2/kg/h at 15 , 200.6±11.1, °C 119.2±8.7 mg O2/kg/h at 20 and 271.1±7.5, 194.7±16.7 mg O °C 2/kg/h at 25 , respectively. Thus, OC of °C BFW was higher than BSW both for non-reproductive and reproductive period. Also, OC increased in proportion to the rise in water temperature, and there was no difference of OC between BFW and BSW at each water temperature during the reproductive or non-reproductive period. OC of BFW and BSW showed clear circadian rhythms on photic conditions of reproductive and non-reproductive period, and the fish consumed more oxygen during the dark phase than for the light phase. In particular, OC of BFW during the reproductive period increased more sharply compared to non-reproductive period when the increase of water temperature was accompanied by the shift from dark to light phase. This implies that they react to the light more sensitively for reproductive period than for non-reproductive period.

Quality Characteristics of Starry Flounder Platichthys stellatus Meat Reared in Different Salinity

This study was performed to evaluate the food value of starry flounder Platichthys stellatus reared in different salinity. Results of salinity experiment in starry flounder clearly showed that there were no significant difference among cohesiveness and hardness except springiness. Proximate composition of muscle, crude lipid at the salinity 0 psu was significantly higher than those 15 psu and 33 psu, but there was no significant difference in terms of crude protein, moisture and ash. While variations in some amino acid composition, serine and threonine contents were observed among fishes reared in different salinity of water, but no significant difference among the other amino acid contents. Muscle fatty acid composition showed significant difference among C16:0, C16:1n-7, C20:1n-9, C22:5n-3 and C24:0. Results of a sensory evaluation clearly indicated that there were no significant difference in odor and color of fish muscle reared in different salinity. But taste, texture and overall acceptability showed the lowest values in 0 psu.

Effects of Water Temperature and Salinity on Blood Properties and Oxygen Consumption in Hagfish (Eptatretus burgeri)

Abstract Hagfish Eptatretus burgeri is classified as a agnathans and has many different physiological properties compared with vertebrates. In this study, we examined effects of water temperature and salinity on blood properties and oxygen consumption in hagfish. In the experiment of water temperature change, hematocrit (Ht), red blood cell (RBC) and glucose of hagfish blood revealed the lowest values at 15℃. Oxygen consumption of hagfish had significantly increased with rising water temperature, and the increasing rate was twice as much when the temperature was manipulated every 5℃. Also, oxygen consumption during the night time (a short photoperiod) was significantly higher than that of the daytime. Q10 level was 3.50 in the light period and 3.92 in the dark period. No significant change in plasma glucose level was showned in changing salinity from 30 psu to 22 psu, while it had rapidly increased at 20 psu (13.7±4.0 mg/dL) and thereafter all hagfish were dead at 18 psu. However, osmolarity, Na+, K+ and Cl- levels had significantly decreased when salinity decreased. This results are expected to develop the artificial rearing techniques of natural hagfish.Key words : Hagfish, Water temperature, Salinity, Blood property, Oxygen consumptionCorresponding author : 051-629-5915, yjchang@pknu.ac.kr* (2013 ) .