• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.5
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• pp.541-546
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• 2017

Feeding habits of dolphinfish Coryphaena hippurus, were analyzed. Fish samples were collected by using a purse seine, fishing and set net in the southern sea of Korea from January to December 2015. The size of C. hippurus ranged from 23.8 to 127.4 cm in fork length. The species with the highest percent index of relative importance (%IRI; the most important prey taxa) in the diets of C. hippurus were teleosts and cephalopod, including Engraulis japonicus, Thamnaconus modestus and Trachurus japonicus, Loligo edulis was the most frequently consumed cephalopods. Coryphaena hippurus also ate small amounts of amphipods and carid shrimp. The dietary compositions of C. hippurus was not significantly different among size classes or seasons (ANOSIM, P>0.05). As body size of C. hippurus increased the mean number of prey per stomach (mN/ST) tended to decrease, but the opposite trend was evident for mean weight of prey per stomach (mW/ST). The mN/ST and mW/ST also significantly varied with season (one-way ANOVA, P<0.05).

• Fisheries and Aquatic Sciences
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• v.22 no.12
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• pp.29.1-29.7
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• 2019

Veterinary drugs are widely used to protect production-related diseases and promote the growth of farmed fish. The use of large amounts of veterinary drugs may have potential risk and cause adverse effects on both humans and the environment. In this study, we developed risk-based ranking based on a scoring system to be applied in the national residue program. In this approach, the following three factors of veterinary drugs that may occur as residues in fishery products were considered: potency (acceptable daily intake), usage (number of dose and withdrawal period), and residue occurrence. The overall ranking score was calculated using the following equation: potency × usage (sum of the number of sales and withdrawal period) × residue occurrence. The veterinary drugs that were assigned high score by applying this approach were enrofloxacin, amoxicillin, oxolinic acid, erythromycin, and trimethoprim. The risk-based approach for monitoring veterinary drugs can provide a reliable inspection priority in fishery products. The developed ranking system can be applied in web-based systems and residuemonitoring programs and to ensure safe management of fishery products in Korea.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.4 no.1
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• pp.1-6
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• 1971

In order to study the catching efficiency of shrimp trawl equipped with electrodes around the net mouth and stimulant devices attached to the ground rope, an experimental operation was carried out at Oma-Island Shrimp Farm from October 3rd to November 5th, 1970. Many studies have been made on the shrimp trawl with electric stimulant devices, but few can be found for detailed scientific catching methods. Electric power consumption was so excessive that electric stimulant devices could not be developed for commercial purposes. As a first step toward the successive operations of the electric stimulant devices in the field, it is necessary to study fundamental principles, such as electric current, voltage, electric potential, potential difference, electric field and suitable pulse. The behaviour response of the common shrimp, Penaeus japonicus BATE to moving nets and electric stimulant devices were reported in the preceding papers based on the water tank experiments (Ko and Kim, 1970). Through comparative fishing tests the rate of catching efficiency during daylight time was confirmed to be from 89 to 96 per cent of the night catch efficiency, and with 30 V. 1.5 A. electric power was sufficent for practical sea operation.

• Fisheries and Aquatic Sciences
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• v.15 no.4
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• pp.345-352
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• 2012

To predict catches of Pacific anchovy Engraulis japonicus larvae, anchovy eggs were collected in the coastal waters off Gunsan, Korea, in the Yellow Sea during the main spawning season (June to July) from 2003 to 2009. A ring net was repeatedly towed vertically at 10 stations during the daytime to sample eggs. Catch data estimated by auction sales were obtained from the Fisheries Cooperatives Union of Gunsan City and daily water temperature data in the outer harbor of Gunsan City during the survey periods were obtained from the National Oceanographic Research Institute. A significant relationship was found between anchovy egg density from June to July and larval catch from July to October in the same year. Catch of anchovy larvae in Gunsan were also high when optimal growth temperatures were recorded in the coastal waters off Gunsan in July. Although the recruitment success or failure of anchovy larvae can be predicted from variability in egg density, we suggest that mean daily water temperature is a more efficient indicator for predicting variability in catches of larval anchovy in the Yellow Sea.

• Fisheries and Aquatic Sciences
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• v.14 no.2
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• pp.130-137
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• 2011

Visual stimuli of nets, which affect fishing selectivity, vary by twine diameter, color, and material under different light conditions and visual geometries. In this study, two cylindrical model codends of two mesh sizes, 28 and 43 mm, were made of high-contrast, dark brown polyethylene (PE) netting twine and low contrast, light-blue polyamid (PA) monofilament twine. Each model codend was filled with juvenile seabream and set in the water channel of a light-blue circular tank under a flow speed 0.8 m/s for 30 min. Light conditions were set to relatively bright, dim, and dark. The resulting retention rates of juvenile seabream were 15-35% lower for the low-contrast codend with PA monofilament than for the high contrast PE twine netting under bright and dim light conditions, while no difference was observed under dark conditions. The effects of mesh size and netting contrast on the retention rate were dependent on the light level, while the retention rate due to netting contrast was independent of mesh size. Therefore, low-contrast nets in the codend could help to reduce juvenile bycatch by disturbing the orderly optomotor response.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.6
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• pp.801-806
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• 2013

Spiny lebbeid shrimp Lebbeus groenlandicus larvae were reared in the laboratory to estimate the energy budget from the zoeal to the post-larval stage. Energy expended by larvae on growth and respiration was determined from values for feeding, growth, molting, and metabolism. We calculated that 16.22 J were used for growth throughout all larval stages. Energy loss during molting was estimated as 1.03 J, and energy used for respiration was estimated as 1.31 J. Energy taken in by feeding was estimated as 77.16 J, while the sum of energies expended in excretion and egestion was 58.61 J. Larvae were estimated to assimilate 24.6% of ingested food as energy and to use ~85% of the assimilated energy for somatic growth. Gross growth efficiency ($K_1$) and net growth efficiency ($K_2$) were shown to be ~22% and 93%, respectively. Maintenance costs of respiration were estimated as ~9.7% of assimilated energy.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.6
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• pp.807-812
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• 2013

The energy budget of the larvae of pandalid shrimp, Pandalopsis japonica, reared in the laboratory from zoea to post-larva was investigated. Energy used during the growth of the shrimp larvae was calculated daily for feeding, growth, molting, and metabolism. The total energy used was 16.2 J for the entire larval stage. Molting energy loss was estimated at a total 1.03 J. Energy used for respiration was estimated at a total of 1.85 J. The intake energy by feeding reached a total of 77.69 J. The total sum of energies used by excretion and egestion was 58.61 J. Larvae assimilated 24.57% of ingested food and used 84.91% for somatic growth. The gross growth efficiency ($K_1$) was 22.19% for the entire larval stage, and the net growth efficiency ($K_2$) was 90.31%. Maintenance costs were estimated at 9.69% of assimilated energy for the entire larval stage.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.5
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• pp.381-390
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• 1987

To evaluate the effects of the cooling water system on the primary production of marine phytoplankton, a series of experiments were made at the cooling water system of Samchonpo Power Plant from May 1985 to May 1986. Mechanical and physiological perturbations of the entrained process are the most detrimental to the primary production of marine phytoplankton. Nevertheless the primary production is increased by the heated water within the upper limit of temperature tolerence of the phytoplankton. The cooling water system, on the average, reduces the gross production and net production by 4.6 to 12.1 and 8.4 to $11.9\;mgC/m^3/h$, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.10 no.1
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• pp.49-52
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• 1977

The author has collected as many as 35 species belonging to 25 genera in 18 families by trap net in the fishing ground of Chromis notatus along Seogwipo coast in Jeju-do. Among 35 species included are 6 species of Labridae, 4 species of Scorpaenidae, 3 species of Pomacentridae, and 3 species of Monacanthidae. In regard to the amount of catch, more than $90\%$ are Chromis natatus which are mainly caught within the depth of $15\~25m$, and the rest are largely Apogon semilineatus and those belonging to Labridae. ; Some ornamental fishes, subtropical fishes and some rare species are also collected.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.5
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• pp.649-652
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• 2013

Distribution and migration of larval and juvenile sandfish Arctoscopus japonicus in the coastal waters off Gangwondo were determined monthly from samples collected by a rectangular bottom net in the coastal waters off Gangwondo from March to July, 2011. Fish were collected in abundance from the northern waters from March to June. The average total length (${\pm}SD$) was $11.5{\pm}1.6$ mm in March increased up to $53.5{\pm}3.3$ mm in June. The size distribution of sandfish by depth suggested that the fish grew waters less than 50 m deep until June, before moving deeper waters of around 100 m.