• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.34 no.4
• /
• pp.419-421
• /
• 2001

Heritability estimations of masu salmon smelt at underyearing of age were described. Masu salmon was taken from aquaculture station of Mori in Japan. After fertilization, the offsprings in each family were reared in separate egg trays and fingerling tanks. The percentage of fish in each tank which smoltified at 11-month old was recorded, and environmental and genetic factors influencing the percentage smoltification were also studied. Percentage of smoltification was not significantly affected by the number of fish held in a tank, or fish density (correlation coefficient 0.10). However, there was a high correlation ($0.821\~0.565$) between smelt percentage and growth related traits of fish in a family. Heritability estimated from total data was $0.47\pm0.13$, when effects of tanks were ignored.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.60 no.2
• /
• pp.128-141
• /
• 2024

Fish resource surveys were conducted near Jeju Island in June, August and October 2021 using an underwater camera monitoring system, fish pots, and SCUBA diving methods. The efficiency of the methods used to survey fish resources was compared using the number of individuals compared to area per unit time (inds/m³/h) and the number of species compared to area per unit time (spp./m³/h). As a result of comparing the number of individuals compared to the area per unit time (inds/m³/h), the order was underwater camera 214.69, SCUBA diving 124.62, and fish pots 0.57 inds/m³/h. The number of species compared to area per unit time (spp./m³/h) is in the following order: SCUBA diving 0.85, underwater camera 0.38, and fish pots 0.01 spp./m³/h. The fish resource monitoring method using underwater cameras was found to be more efficient in individual counts, and the SCUBA diving method was found to be more efficient in species counts. When considering cost and survey efficiency, the fish resource survey method using underwater cameras was judged to be more effective. The results of this study are expected to be widely used in estimating the population density of fish, which is the core of future fisheries resource surveys.

• Journal of fish pathology
• /
• v.28 no.1
• /
• pp.37-42
• /
• 2015

In the present study, we performed a dipping of olive flounder (average length and weight: $20{\pm}2.0cm$, $70{\pm}5.0g$) for a period of three hours a day, over two days, in a melted complex of oxytetracycline (OTC) and neomycin (N), by dissolving 25-10 ppm or 50-20 ppm in water. Subsequently, the remaining antibiotic density in muscle tissue collected from olive flounder was investigated, 1, 5, 14 and 40 days after discontinuation of the medication. 5 fish were used from each group. The standard graph drawn from the results of diluting two standard solutions of OTC and N based on various density levels, showed a relatively straight line with an $R^2$ of 0.9999 and 0.9952, respectively. The recovery rate of OTC was shown to be 90-93% and N, 88-95%. Upon measurement of the remaining antibiotic density in the test group that had been exposed to 25-10 ppm of the complex of OTC and N, $0.97{\pm}0.084{\mu}g/ml$ of OTC and $0.118{\pm}0.079{\mu}g/ml$ N were detected on 1 day of the test. No antibiotic density was detected after day 5 of the test. Regarding the test group that were exposed to 50-20 ppm of the complex of OTC and N, $1.324{\pm}0.062{\mu}g/ml$ of OTC and $0.788{\pm}0.05{\mu}g/ml$ N were detected on day 1 of the test, and no antibiotic density was detected after day 5 of the test.

• Journal of Nutrition and Health
• /
• v.45 no.2
• /
• pp.121-126
• /
• 2012

This study evaluated the effect of fish oil rich in n-3 fatty acids on bone characteristics in Sprague-Dawley rats. Weanling male rats were randomized to receive either a diet containing high fish oil (FO), fish oil blended with corn oil (FICO), or soy oil rich in n-6 fatty acids (SO) for 4 weeks. All diets provided 70 g/kg fat based on the AIN-93G diet. Growth and biomarkers of bone metabolism were analyzed, and femur bone characteristics were measured by dual-energy X-ray absorptiometry. After the dietary treatment, no significant differences among the diet groups were observed for serum concentrations of Ca, parathyroid hormone, calcitonin, or osteocalcin. Alkaline phosphatase activity was significantly greater in FO-fed rats compared to that in the FICO and SO groups, whereas no difference in deoxypyridinoline values was observed, supporting the positive effect of a FO diet on bone formation. These results were accompanied by a significant increase in femur bone mineral density (BMD) in FO-fed rats. These findings suggest that providing fish oil rich in n-3 fatty acids correlates with higher alkaline phosphatase activity and BMD values, favoring bone formation in growing rats.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.7 no.4
• /
• pp.195-203
• /
• 1974

The individual production rate of Plecoglossus altivelis was studied from the 18th of June to the 25th of September (99 days) 1973, when the fish grow best at Gangjeong Stream, Jeju Do, as one of the ways to find out the reasons why the size of P. altivelis of Jeju Island is smaller than that of other places. The results obtained are as follows : 1) The indivudual production rate of the fish in the Gangjeong Stream during the summer 1973, was estimated as shown in Table 6. 2) The individual production rate of the fish and standing crop of algae on stones in the Gang-jeon Stream were no more than $7.2\%$ and $6.2\%$ respectively, when compared with those of the Ukawa River (which is located in Japan), thus the individual production rate of the fish at Gang-jeong Stream being very poor. 3) Population density was 5.2 individuals average per square meter during the research period. This is beyond the estimated density limit, i. e., 4.8 individuals per square meter, for the standing crop of algae on stones. 4) The period that the individual production rate of the fish was the most brisk during the summer in this stream was from August to September in 1973. 5) The poor individual production rate is primarily regarded due to insufficient gross ingestion. The reasons seemed to be insufficeient productivity of algae on the bottom stones, over-population density of the fish, and the lowered activity of ingestion due to low water temperature in daytime as compared with other places. Thus, the production rate of Plecoglossus altivelis in the Gangjeong Stream during the summer was greatly influenced by these factors.

• Korean journal of applied entomology
• /
• v.28 no.3
• /
• pp.167-174
• /
• 1989

A confined field assessment on the integrated control of vector mosquitoes (Anopheles sinen- sis and Culex tritaent'orhynchus) was conducted by timely treatment of Bacillus thuringiensis(H-14) formulation in the presence of larvivorous fish (Aplocheilus lalipes) in natural rice fields of $30,000M^2$ at Yongam, South Korea Cholla Province from July through October in 1988. In presence of larvivorous fish (Aplocheilus) at lower density of 0.6 fish per $M^2$ water surface, mosquito vector control rates ranged 55. 0~57. 6% from July through August, and when the mosquio density started to increase with over 10 larvae on the average per sample, B.t.(H-14) formulation treatment at the rate of 1. 0 Kg/ha made 100% vectors reduc¬tion in 24 hours, the control sustained above 98% until the test was terminated on October 11th. In the fish introduced rice paddies with Aphyocypris chinensis at the density of above 1. 5 fish per $M^2$, a satisfactory degree of vector control was obtained by 88. 2~96. 7% in 2 week period until September 21st. In the absence of larvivorous fishes, B.t. (H-14) treatment made 100% control in 24 hours, however, vector population rebound appeared in day 7, required to make additional treatment to suppress population down.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.7 no.4
• /
• pp.235-246
• /
• 2002

The fish farming using net cages has been developed in many semi-closed bays in the southern coast of Korea for the last two decades. The intensive cage cultures of fishes generate considerable amounts of organic waste in the form of uneaten food and faeces. In order to evaluate the effect of fish farming activities we collected the benthic macrofauna near the fish farm area located in Wolho Islet of Gamak Bay and in Haklim Island of Tongyeong in November 1998. Benthic macrofaunal assemblages showed dramatic changes in species number, species diversity, and faunal abundance in the region of the fish farm. These changes were clearly observed even at a distance of up to 30 m from the fish farming cage area. Within 5 m from the cage, there was a zone with low species diversity and highest density, dominated by opportunistic polychaete worm, Capitella capitata. By a distance of 15-30 m, this zone presents highest species number and higher density. Our results clearly demonstrated that fish farm area was highly enriched with organic materials, and implied that the fish farm industry and adjacent benthic ecosystem in semi-closed bay will be seriously damaged by self produced organic wastes in the near future.

• Journal of the korean society of oceanography
• /
• v.32 no.4
• /
• pp.202-207
• /
• 1997

Species composition and abundance of fish larvae were studied from May 1988 through August 1989 in the Han River Estuary and adjacent Kyunggi Bay, Korea. Of 23 taxa identified, Coilia nasus, llisha elongata, and Cyprinidae spp. were dominated. Maximum density (3,5771/1,000m)$^3$ occurred in August 1988 and minimum (3/1,m$^3$) in February 1989. O1igo- ormesohaline species dominated during ebb tides while polyhaline species during flood tides. Correspondence analysis revealed that three distinctive species groups; oligohaline species, Coilia nasus, Ilisha elongata and Cyprinidae spp., which dominated at both channels of Kwanghwa Island (stations 1, 2), mesohaline species, Sardinella zunasi and Gobiidae spp., at the mouth of Yeomha Channel (station 3), and polyhaline species, Engraulis japonicus and Syngnathus schlegeli, in the middle of Kyunggi Bay (station 4). Coilia nasus was the most abundant species and reported first time in the study area. Given the species composition and density of fish larvae, the Han River Estuary is considered to be a major spawning and nursery ground for brackish water species such as Coilia nasus, Ilisha elongata and some Cyprinidae spp.

• Animal cells and systems
• /
• v.5 no.2
• /
• pp.117-126
• /
• 2001

Occurence, seasonal changes and vertical distribution of the silica-scaled chrysophytes in a small fish-free pond were studied using electron microscopy (EM) and light microscopy (LM) from October 1998 to July 1999. The phytoplankton community was characterized by Chrysophyta and Cryptophyta. Ten species of the silica-scaled chrysophytes of genera Mallomonas, Synura, Chrysosphaerella and Spiniferomonas were identified by EM, and the most abundant species were Mallomonas akrokomos and M. portae-ferreae. The maximum population density of M. akrokomos was observed in December and several peaks appeared periodically at about one to two month intervals, whereas M. portae-ferreae developed the maximum density in March. The diurnal vertical distribution of M. akrokomos exhibited clear downward migration at night and slightly upward migration in the morning. A complex interaction among physico-chemical and biological factors seemed to affect the vertical distribution of M. akrokomos. However, the seasonal changes of M. akrokomos did not show significant corre1ations with the physico-chemical and some biologica1 factors. Although M. akrokomos was evenly distributed throughout the water column during some experimental periods, the diurnal patterns found in the two diurnal cycles showed consistency in that it clearly avoided the surface water during the day. This suggested that M. akrokomos may be a shade plankton with maximum densities below surface layer.

• Journal of Life Science
• /
• v.11 no.1
• /
• pp.76-82
• /
• 2001

Fifteen species of microorganisms were isolate form the intestines of fishes, fish feed, and ferment. Eleven microorganisms except HY4, HY8, HY12, and HY13 were Gram-positive, and HY1, HY2, HY3, HY5, HY6, and HY7 produced lactic acid. The species of HY1, HY2, HY3, HY4, HY5, HY6, HY13, and HY14 showed some growth in the medium containing 1% of NaCl. Except HY6, HY7, HY8, HY12 and HY5, 10 isolates had proteolytic activity, whereas only HY13 and HY14 had lipase activity. From all the results four isolates (HY3, HY4, HY13 and HY14) were chosen for the degradation of fish wastes. There was no mutual inhibition among the microorganisms, and the optimum temperature and pH for the growth of the mixed culture were found to be 3 2$\^{C}$ and 7, respectively. Under the optimum growth conditions the maximum optical density and the maximum specific growth rate were estimated to be 2.35 and {TEX}$0.46h^{-1}${/TEX}, respectively. Major microorganisms in the mixed culture at the log-phase were HY3 and HY4, which occupied 70%. The degrading efficiency of fish waste by the mixed microorganisms was 2.3 times higher, compared to control. The total amount of free amino acids in the degraded products from fish wastes was 39g/100g protein and little odor was produced by the mixed microorganisms after 48 hours.