• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.39 no.2
• /
• pp.78-84
• /
• 2006

A high performance liquid chromatography assay method for spiramycin in fish muscle was developed. The developed method was evaluated and validated by monitoring spiramycin in olive flounder (Paralichthys olivaceus), black rock fish (Sebastes schlegeli) and in live conger eel (Anguilla japonica) in fish farms and distribution centers. Using the developed method, the recovery rate was up to 82.4-88.8%, which was higher than that of conventional methods (77.6-87.1%). In particular, the proposed sample treatment protocol was suitable for use with fish samples to remove low molecular weight materials and pigments that could interfere an accurate analysis. The prepared stock solution was very stable, and it remained chemically stable for 5 weeks at $4^{\circ}C$. The performance limit of the developed method for spiramycin acid in fish muscle was 0.05 ppm. One hundred thirty-four fish samples including olive flounder, black rock fish and live conger eel were analyzed to evaluate the overall efficiency of the modified method and to monitor the actual condition of spiramycin usage in fish farms. Olive flounder and black rock fish were collected from fish farms in coastal areas of Korea, and live conger eels were purchased from a fish market in the Busan area from September 2001 to March 2002. According to the overall performance of the developed method, it was considered suitable for the monitoring of spiramycin in fish muscle. The suggested method of analysis for spiramycin in fish muscle is registered in the Korean Official Methods of Food Analysis and is currently tieing utilized for fishery products inspection by the Korea Food and Drug Administration and the National Fisheries Products Quality Inspection Service.

• Fisheries and Aquatic Sciences
• /
• v.16 no.2
• /
• pp.117-124
• /
• 2013

We investigated the short-term and local changes in the thermohaline front in the Jeju Strait, Korea, which is usually formed during winter and spring. To do so, we compared Real-Time Observation System by Ferryboat (RTOSF) data with wind data and routinely collected oceanographic data. During February and April 2007, a thermohaline front formed in the Jeju Strait around the 13-$14^{\circ}C$ isotherms and 33.0-33.5 isohalines. The thermohaline was clearly weakened and began moving southward in mid-March. The variations in the surface temperature and salinity showed a continuous north-south oscillation of the thermohaline front with a period of 3-10 days. The speed of the short-term and local fluctuation of thermohaline front was about 5-30 cm/s. We confirmed these findings by examining the variation in the maximum temperature gradient and $14^{\circ}C$ isotherm during the study period. These short-term and local changes had not been previously detected using serial oceanographic and satellite data. Analysis of local wind data revealed a northerly wind fluctuation with a period of 3-10 days, which was clearly related to the short-term and local changes in the thermohaline front. The short-term and local changes of the thermohaline front in the Jeju Strait originated from local changes in the winter monsoon in this area.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.53 no.4
• /
• pp.413-422
• /
• 2017

The objective of this study was to prove possible effects of a habitable place for fish around semi-submersible drilling rig which measured underwater radiated noise, irradiance distribution of rig's light and conducted experimental fishing in Malaysia territory and observed for distribution of fishes around the rig by ROV during drilling operation in the East Sea of Korea. As a result underwater radiated noise was $130dB/{\mu}Pa$ from 156.25 to 187.50 Hz, irradiance distribution of light was between 21.5 and 43.1 lx. Despite this result, underwater radiated noise was not a threat to fish around rig and low irradiance distribution of light also played a role in the luring influence of the fishes at night. Fish showed up in the beginning of drilling operation and at the end of drilling operation. However, there are few fish in the midst of drilling operation. The main reason for this result was the destruction of the habitable place due to blow out mud and broken pieces of ground formation in drilling hole. The results are expected to contribute to reasonable fishery management around rig.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.46 no.2
• /
• pp.103-114
• /
• 2010

For an effective management of fisheries resources, we need fisheries informations necessary for the establishment of reasonable fishing effort and TAC distribution. To study the present state of by-catch and discard of gill-net fishery in the East Sea, we carried out fishing research using trammel nets in the coastal sea of Susan-port (Yangyang), Jangho-port (Samcheok) and Hupo-port (Uljin). As a result, a total of catch of Susan was 259,172g and that of Hopo was 577,638g. Thus Catch of Susan was 1.49 times more than that of Hupo considering the number of used fishing gear. And catch of Janho was 7.4 times more than that of Susan considering the number of experiment. Two methods of by-catch analysis in this study were used, one method is standardizing of listed species catching possible in fishing license, another method is regarding catch species under 1% of total catch as by-catch. As a result of by-catch analysis of two method, by-catch rate of Susan was 6.55% and 5.87% respectively, that of Hupo was 44.70% and 5.24% and that of Jangho was 0.96% and 2.31%. Discard rate of fish in Susan, Hupo and Jangho were 1.59%, 3.42%, 2.23% respectively.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.18 no.1
• /
• pp.67-73
• /
• 1985

The relationship between the fishing grounds of Buse, Pseudosciaena crocea (Richardson), and oceanographic condition in the Yellow Sea and the East China Sea is studied on the basis of the data of the catches of stow net fishery (Fisheries Research and Development Agency, $1967{\sim}1979$) and the oceanographic observation data. The main fishing grounds of the Buse was concentrated in southwestern area of Cheju island and the best catch was in April. CPUE was less than 50 kg/haul in the most pare of fishing grounds, there-fore the conditions of fishing grounds generally were poor and coefficients of variance were also large. In the main fishing period, April, the fishing grounds were generally distributed in colder region of $8^{\circ}C$ through $10^{\circ}C$ isotherm at 50 m depth, than Yellow croaker and Gangdali which were distributed between $10^{\circ}C$ and $15^{\circ}C$.

• The Journal of Fisheries Business Administration
• /
• v.45 no.2
• /
• pp.61-72
• /
• 2014

This study aimed to empirically investigate the applicability of ecosystem-based TAC (Total Allowable Catch) fisheries management targeting the large purse seine fishery where multi-species are regulated by TAC. Using a linear programming, the optimal fishing effort and the catch amount by species which maximize fishing profits were analyzed under the constraint condition of catch limits by species. Analytical results showed that an application of TAC on only chub mackerel would have negative impacts on fish stocks such as hairtail and jack mackerel by increasing the level of fishing effort to achieve its allocated catch limit. However, under the constraint condition of catch limits of all species, it was shown that optimal catches of all species were achieved within their catch limits. It implies the importance of ecosystem-based management considering biological and technical interactions of species those were excluded in the traditional single species fisheries management.

• KSBB Journal
• /
• v.25 no.6
• /
• pp.547-552
• /
• 2010

The recent bloom of a very large jellyfish Nemopilema nomurai has caused a danger to sea fishery and sea bathers. Presently, Nemopilema nomurai is thrown away through a separator system in the sea. The objective of this work was to produce bio-gas from Nemopilema nomurai by using anaerobic digestion. The bio-gas includes the hydrogen or the methane gases. It relates that Nemopilema nomurai is effectually changed into the renewable energy. When the jellyfish biomass was used as an organic carbon source the bio-gases were evolved. The aim of this study was to determine the optimal conditions for hydrogen and methane gases production according to the substrate concentrations of Nemopilema nomurai, optimal culture condition and the sludge-pretreatment without pH control. The optimal culture condition was found to be $35^{\circ}C$ and the heat-treatments of jellyfish was done at $120^{\circ}C$ for 30 min. The production rate of hydrogen and methane gas were found to be 8.8 mL/L/h, 37.2 mL/L/h from 1.5 g of dry Nemopilema nomurai.

• Journal of Fisheries and Marine Sciences Education
• /
• v.28 no.6
• /
• pp.1651-1661
• /
• 2016

The purpose of this study is to draw up a plan for improving working conditions of distant water fishing vessel crew in order to revitalize the declining distant water fishing industry. Land-based employment has increased as the result of industrialization, which in turn created shortage in marine crew supply for distant water fishing vessels. Pressure on increasing wages for sea farers is put on the industry for this reason, making the labour market in the distant water fishing industry tougher and tighter. Multiple issues have yet to be addressed for distant water fishing vessel crew. They suffer from excessive work compared to other industries. Crew management is another issue, as sea farers face poor labour conditions, working on board vessels in a collective way where no autonomous actions are allowed. Other issues include unqualified crew supply, increasing ratio of labour costs for crew to sales, and intensified implications of labour unions, which are as well making crew supply difficult as a whole. To this end, more well-qualified workers should take part in production operations in the distant water fishery. Both wage increase and working condition improvement should be achieved in order to strengthen motivation towards qualified sea farers. Sustainable crew supply can be achieved when working environments, gender-based working conditions, welfare are prioritized and improved as a whole.

• Journal of applied mathematics & informatics
• /
• v.38 no.1_2
• /
• pp.13-36
• /
• 2020

In this paper, we have presented a multispecies prey-predator harvesting system based on Lotka-Voltera model with two competing species which are affected not only by harvesting but also by the presence of a predator, the third species. We also assume that the two competing fish species releases a toxic substance to each other. We derive the condition for global stability of the system using a suitable Lyapunov function. The possibility of existence of bionomic equilibrium is considered. The optimal harvest policy is studied and the solution is derived under imprecise inflation in fuzzy environment using Pontryagin's maximal principle. Finally some numerical examples are discussed to illustrate the model.

• Journal of Advanced Marine Engineering and Technology
• /
• v.25 no.6
• /
• pp.1324-1329
• /
• 2001

The depression of the external situation like the departure of WTO system and the plan of EEZ proclaim is forcing fishery into improving their fishing condition. By this international and domestic circumstance, development of the sea water cooling apparatus for fish hold storage is demanded sincerely. This study represents the thermal characteristics of the fish hold storage during transportation. The numerical analysis in this study is the finite volume method with the SIMPLE computational algorithm to study the seawater flow behavior in the fish hold storage. The computation were carried out with the variations of the circulating flow velocity and depth of fish hold storage. As the result of the three dimensional simulations, the mean temperature doesn't almost change by the circulating flow rate. find the mean temperature is suddenly changed by the ratio of depth of fish hold storage.