• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.53 no.6
• /
• pp.918-924
• /
• 2020

This study investigated diurnal fasting and postprandial total ammonia nitrogen (TAN) excretion rates in juvenile Oplegnathus fasciatus (rock bream; mean body weight 45.8±1.1 g) at three temperatures (15, 20, and 25℃) in a recirculating system (three replicates). The fish were hand-fed twice daily (09:00 and 17:00 h) with commercial food (46.7% protein) until satiation. The results showed that the fasting and postprandial TAN excretion rates were temperature-dependent. The mean hourly rates were 7.7 (15℃), 10.2 (20℃), and 11.9 (25℃) mg kg fish-1 h-1 for fasting and 34.0 (15℃), 47.8 (20℃), and 60.2 (25℃) mg kg fish-1 h-1 for postprandial. At each temperature, two postprandial TAN excretion peaks were observed 2-4 h after feeding; the second peak was always higher. The TAN loss to nitrogen consumption ratio was 41.1-46.8 % and increased significantly with increasing temperature. Temperature affected fasting and postprandial TAN excretion in juvenile rock bream, providing insight for culture management.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.49 no.5
• /
• pp.600-606
• /
• 2016

The effects of feeding frequency on the growth, food consumption, body composition, and hematological response of the Korean rockfish Sebastes schlegelii were investigated for 77 days at ambient water temperatures (17.2-24.5℃) in a sea cage in Tongyeong, Korea. Three replicate groups of fish were hand-fed to satiation with a commercial diet in one of four different feeding frequency trials (one meal every 2 days, and one, two and three meals per day). At the end of the experiment, the mean weight gain, specific growth rate, and daily feed intake of fish fed one and two meals per day were significantly higher than those of fish fed one meal every 2 days or three meals per day. The feed efficiency of the fish fed three meals per day was significantly lower than that of the fish in the other groups. The glucose concentration of fish fed one meal every 2 days was significantly higher than that of the other groups. We conclude that the optimum feeding frequency for improving the growth of Korean rockfish weighing 100-200 g reared in sea cages is one meal per day under our experimental conditions.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.42 no.6
• /
• pp.537-544
• /
• 2009

This study was conducted to improve yield and functional properties of autoclave-treated salmon frame extracts (SFETA) using commercial enzymes (Alcalase 2.4 L FG, Flavourzyme 500 MG, Neutrase 0.8 L and Protamex 1.5 MG). Yield and angiotensin I converting enzyme (ACE) inhibitory activity of all enzymatic hydrolysates improved compared to those of control (undigested extracts), which were the highest in hydrolysates incubated with Protamex 1.5 MG for 4 hrs (P4-treated hydrolysates) and 2 hrs (P2-treated hydrolysates), respectively. However, antioxidant activities of all enzymatic hydrolysates showed less than 29%. According to the trichloroacetic acid soluble-N, volatile component intensity and sensory evaluation, when compared to control, taste of P4-treated hydrolysates improved, while its fish odor strongly smelt. Therefore, for efficient use of P4-hydrolysates, the fish odor should be improved by Maillard reaction of extracts or pre-treatment of salmon frame.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.46 no.6
• /
• pp.761-768
• /
• 2013

We conducted two feeding trials to investigate the optimal feeding frequency of juvenile Korean rockfish Sebastes schlegeli fed a commercial diet of expanded pellets containing 47.2% crude protein, 9.2% crude lipid, and 14.5% ash at two different water temperatures. In the first experiment, triplicate groups of 20 fish with an average weight of 2 g were fed an equal amount of diet (5.97% based on body weight) at one of six feeding frequencies (2, 3, 4, 5, 7, or 9 meals/day) for four weeks at $17.5^{\circ}C$. After four weeks, we measured weight gain (WG), specific growth rate (SGR), feeding efficiency (FE), and protein efficiency ratio (PER). Fish fed diet five meals/day grew significantly better than those fed nine meals/day. The second experiment used identical experimental conditions and feeding regions, except the food ration was slightly less (5.92% based on body weight) and the water temperature was increased to $20^{\circ}C$. After four weeks, we again measured WG, SGR, FE and PER. Fish fed seven meals/day grew significantly faster than those fed 2, 3, 4, or 9 meals/day. Whole-body protein levels in fish fed three meals/day was higher than those fed four meals/day in $17.5^{\circ}C$ water, but whole-body lipids in the fish fed four meals/day was higher than those fed two meals/day in $20^{\circ}C$ water. A second-order polynomial analysis based on WG suggested the optimal feeding frequency for juvenile Korean rockfish was five meals/day at $17.5^{\circ}C$ and six meals/day at $20^{\circ}C$, indicating that fish reared in higher water temperature require higher feeding frequencies.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.35 no.10
• /
• pp.1467-1474
• /
• 2006

Fish-frames, which are left after obtaining fillets or muscle during fish processing, consists of useful food components, such as muscle, collagen, calcium, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). This study was carried out to prepare snack using conger eel frame (SF) for human consumption and also to elucidate food component characterization of the snack. The results of volatile basic nitrogen suggested that conger eel frame was a suitable material for preparing snack. Based on the results of sensory evaluation and costs, starch syrup was an optimal sweetener for preparing snack using conger eel frame. The starch syrup-treated SF appeared safe because the moisture content and peroxide value were below the safety limits described in the guideline of Korea Food and Drug Administration (KFDA). Starch syrup-treated SF was similar in the pattern of fatty acid composition to soybean oil, whereas EPA and DHA were detected in SF. The total content of amino acid in starch syrup-treated SF was 23.9% based on 100 g of raw material. The maj or amino acids were aspartic acid, glutamic acid, glycine and alanine. The total contents of calcium and phosphorus in starch syrup-treated SF were 4.9% and 2.8%, respectively. The Ca/P of starch syrup-treated SF was 1.9, which is a good ratio for absorption of calcium. The SF made with starch syrup was superior in EPA and DHA compositions, total amino acid, calcium and phosphorus contents to commercial snack using eel frame.

• Journal of Aquaculture
• /
• v.19 no.2
• /
• pp.95-98
• /
• 2006

This study was performed to determine possibility of compensatory growth of juvenile olive flounder fed a commercial feed during the summer season. Five treatments of fish with triplicates were prepared: C, S1, S2, S3 and S4. Fish in the control group (C) was hand-fed with the commercial feed to apparent satiation twice daily for 6 days a week during 6 weeks. Fish in S1, S2, S3, and S4 experienced 1, 2, 3, and 4 weeks of starvation before fed to satiation twice daily for 5, 4, 3, and 2 weeks, respectively. The feeding trial lasted far 6 weeks. Survival of flounder in C, S1 and S2 was significantly (P<0.05) higher than that offish in S4. Weight gain and specific growth rate (SGR) of flounder in C and S1 were significantly (P<0.05) higher than those of fish in S2, S3 or S4. And weight gain and SGR of flounder in S2 and S3 were significantly (P<0.05) higher than those of fish in S4. Feed consumption of flounder tended to increase with weeks of feeding. Feed efficiency ratio and protein efficiency ratio for flounder in C, S1, S2 and S3 were significantly (P<0.05) higher than those for fish in S4. Moisture content of the whole fish in C was lowest, but highest for fish in S4, respectively. Crude protein content of the whole fish in C was highest, but lowest far fish in S4, respectively. Crude lipid content of the whole fish in C, S1 and S2 was significantly (P<0.05) higher than that of fish in S4. In conclusion, full compensatory growth was obtained in juvenile olive flounder fed for 5 weeks after 1-week feed deprivation during the summer season. Compensatory growth of fish was well supported by improvement in feed efficiency ratio and protein efficiency ratio.

• Journal of Fisheries and Marine Sciences Education
• /
• v.24 no.4
• /
• pp.602-608
• /
• 2012

This study was conducted to evaluate the effect of commercial extruded pellet (EP) diet on the growth and water quality compared with a raw fish moist pellet (MP) diet for flounder on field feeding experiments. Three replicate groups of 130 fish per each tank (initial weight of 380 g) were fed one of the EP and Moist pellet (MP) for 7 months. In field feeding experiment, no significant difference was observed in final mean weight of fish fed the experimental EP (1,233 g) and MP (1,237 g), and any noticeable problem caused by feeding the experimental EP was not found during the whole period of feeding trial. Feed efficiency of fish fed the experimental EP was higher than that of MP, and there was no significant difference in survival between the fish fed experimental EP and MP. The concentrations of SS, COD, TN and TP of seawater in tanks of MP groups were 1-5 times higher than those of EP groups. Therefore, these results strongly suggest that diet EP could be developed to replace MP diet for the marketable size of production for flounder without adverse effects on growth performance and water quality.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.46 no.2
• /
• pp.186-194
• /
• 2013

We compiled and analyzed long-term time-series data collected in Korea to evaluate changes in oceanographic conditions and marine ecosystems near Jeju Island ($33^{\circ}00^{\prime}-34^{\circ}00^{\prime}\;N$, $125^{\circ}30^{\prime}-127^{\circ}30^{\prime}\;E$) from 1981 to 2010. Environmental data included depth-specific time series of temperature and salinity that have been measured bimonthly since 1961 in water columns at 175 fixed stations along 22 oceanographic lines in Korean waters by the National Fisheries Research & Development Institute, and time series of estimated volume transport of the Tsushima Warm Current (TWC) and Korea Strait Bottom Cold Water (KSBCW) for the period from 1961 to 2008. We analyzed the species composition in terms of biomass of fish species caught by Korean fishing vessels in the waters near Jeju Island (1981-2010). Data were summarized and related to environmental changes using canonical correspondence analysis (CCA). The CCA detected major shifts in fish community structure between 1982 and 1983 and between 1990 and 1992; the dominant species were a filefish during 1981-1992 and chub mackerel from 1992 to 2007. CCA suggested that water temperature and salinity in the mixed layer and the volume transport of the TWC and the KSBCW were significantly related to the long-term changes in the fish community in the waters off Jeju Island. Fish community shifts seemed to be related to the well-established 1989 regime shift in the North Pacific. Further studies are required to elucidate the mechanisms driving climate change effects on the thermal windows and habitat ranges of commercial species to develop fisheries management plans based on reliable projections of long-term changes in the oceanographic conditions in waters off Jeju Island.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.48 no.6
• /
• pp.864-875
• /
• 2015

This study investigated the sanitary characteristics of commercial salted semi-dried convict grouper Epinephelus septemfasciatus (SSD-CG) and longneck croaker Pseudotolithus typus (SSD-LC) and suggested standards for salted semi-dried fish (SSD-F), based on the domestic standards for salted mackerel (Scomber japonicus or kwamegi) and salted dried yellow corvenia (Pseudosciaena manchurica), and sanitary characteristics of commercial SSD-F. For the commercial SSD-CG and SSD-LC, respectively, the moisture content ranged from 64.6-76.1 and 65.7-77.5%, salinity from 2.7-8.2 and 1.5-4.9%, volatile basic nitrogen (VBN) from 22.1-88.2 and 13.5-87.4 mg/100 g, peroxide value (POV) from 17.2-195.0 and 28.5-190.2 mEq/kg, and viable cell counts from 6.1-8.4 and 5.4-7.2 log (CFU/g). No Escherichia coli was detected in six kinds of SSD-CG or three kinds of SSD-LC. The standard for controlling the quality of SSD-F is the moisture content (>68%), salinity (>3%), VBN content (>50 mg/100 g), POV (>60 mEq/kg), viable cell counts (>$10^6$ CFU/g), E. coli (>MPN/100 g), and others. Using the established standards, no commercial SSD-F passed. The chemical, microbial, and other results for commercial SSD-F suggest that provisions for controlling the quality of high-quality SSD-F should be established.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.53 no.3
• /
• pp.281-289
• /
• 2020

This study was conducted to evaluate fish cake made from salmon Oncorhynchus keta frame muscle (FC-SFM) in terms of taste, flavor, and nutritional characteristics. FC-SFM was significantly higher in moisture and lower in ash and carbohydrate than commercial fish cake (CFC). There were no significant differences in protein and lipid contents between FC-SFM and CFC (P<0.05). The total amino acid content of FC-SFM was higher than that of CFC. The major amino acids found in FC-SFM were aspartic acid and glutamic acid. The mineral content based on 100 g of FC-SFM was 76.7 mg calcium, 126.3 mg phosphorus, 19.1 mg magnesium, and 88.7 mg potassium. The total fatty acid content of FC-SFM was 1,833 mg/100 g, which was lower than that of CFC. The major fatty acids found in FC-SFM were 16:0, 18:1n-9, and 18:2n-6. The eicosapentaenoic acid and docosahexaenoic acid content of FC-SFM was higher than that of CFC. The results suggest that FC-SFM has different nutritional characteristics to CFC, and FC-SFM could be commercialized.