• Journal of Environmental Science International
• /
• v.17 no.8
• /
• pp.841-856
• /
• 2008

This research outlines a new method for evaluation of shellfish production in Gamak Bay based on the concept of EMERGY. Better understanding of those environmental factors influencing oyster production and the management of oyster stocks requires the ability to assess the real value of environmental sources such as solar energy, river, tide, wave, wind, and other physical mechanisms. In this research, EMERGY flows from environment sources were 76% for shellfish aquaculture in Gamak Bay. EMERGY yield ratio, Environmental Loading Ratio, and Sustainability Index were 4.26, 0.31 and 13.89, respectively. Using the Emergy evaluation data, the predicted maximum shellfish aquaculture production in Gamak Bay and the FDA (Food and Drug Administration, U.S.) designated area in Gamak Bay were 10,845 ton/y and 7,548 ton/yr, respectively. Since the predicted shellfish production was approximately 1.3 times more than produced shellfish production in 2005, the carrying capacity of Gamak Bay is estimated to be 1.3 times more than the present oyster production.

• Journal of Fisheries and Marine Sciences Education
• /
• v.12 no.1
• /
• pp.98-121
• /
• 2000

The Korean fishery encountered a difficulty situation, due to the new regime of the Exclusive Economic Zone (EEZ) and the decreasing fisheries resources in Korean waters. In addition, the coastal areas are deteriorated by industrial wastes, sewage, farming wastes and pollution from aquaculture. In this situation, it is necessary to study the TAC (total allowable catch) - based management system, the development of fishing gears and appropriate fishing methods for stock conservation, and the automation system of fishing gears for improving the efficiency of fisheries. The objective of this study is to look for an appropriate system in marine production and resource management under the new UNCLOS (United National Convention for the Law of the Sea) regime for subjects in fishing gears and methods, production system, and information, and fisheries resources management. The results of this study could be used as scientific information to maintain and develop the Korean fisheries and to establish fisheries policy for the management of fisheries resources in Korean waters.

• The Korean Journal of Malacology
• /
• v.29 no.3
• /
• pp.251-258
• /
• 2013

This study aims to find out a suitable cryoprotective agent (CPA) for cryopreservation and its optimum concentration in order to conduct planned artificial seed production of Pacific oyster, Crassostrea gigas and to preserve superior sperm. For this, we tried to understand toxicity and the effect of cryopreservation by CPA type and concentrations first and then looked into cell damage of the sperm after thawing. Toxicity analysis on the sperm of Pacific oyster according to different CPA and immersion time shows that dimethyl sulfoxide (DMSO) comes first when it comes to survival rate and mobility followed by ethylene glycol (EG), glycerol and methanol. To identify the optimum CPA and its level, filtered seawater was used as a diluent before cryopreservation for 30 days. As a result, cryopreserved sperm of Pacific oyster with 15% of DMSO showed the highest survival rate and activation. Also, we observed the cryopreserved and thawed sperm with Scanning electron micrographs by CPAs and concentrations. Consequently, DSMO showed the lowest cell damage followed by EG, methanol, glycerol and the level was 15, 20, 10, 5% respectively. In a nutshell, it is proven that the optimum CPA and its level is 15% of DMSO.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.42 no.6
• /
• pp.604-608
• /
• 2009

This study was conducted to evaluate extruded pellet (EP) diet compared with a raw fish moist pellet (MP) diet for flounder, Paralichthys olivaceus on field feeding experiments in Jeju area. The experimental EP diet (juvenile, growing and adult) was prepared based on the former studies on nutrient requirements and feed ingredient of flounder. Fish were distributed randomly to each aquarium as a group of 102,300 fish (initial mean weight 97 g) in field experiment I and reared randomly to each aquarium as a group of 40,000 fish (initial mean weight 120 g) in field experiment II. In field feeding experiment I conducted in commercial flounder farm, survival, wt. gain (94-1,090 g), feed efficiency and condition factor of fish fed experimental EP were comparable to those of fish fed MP, but considerably higher protein efficiency ratio were observed in fish fed experimental EP. In field feeding experiment II, no significant difference was observed in final mean weight of fish fed the experimental EP (1,234 g) and MP (1,286 g), and any noticeable problem caused by feeding the experimental EP was not found during the whole period of feeding trial. Survival of fish fed the experimental EP was lower than that of MP, and there was no significant difference in feed efficiency between the fish fed experimental EP and MP. Therefore, these results strongly suggest that diet EP could be developed to replace MP diet for the marketable size (1.3 kg) of production for flounder without adverse effects on growth performance. In particular, abdominal dropsy and reduction of condition factor, which are frequently occurred in commercial EP feeding farms, were not observed in flounder fed experimental EP.

• The Journal of Fisheries Business Administration
• /
• v.51 no.1
• /
• pp.53-66
• /
• 2020

The Ministry of Maritime Affairs and Fisheries is supporting the "Environmentally Friendly Fisheries Promotion and Private Assistance Project" to increase production of eco-friendly, high-value-added foods. Private-backed operators selected for the project will have an economic opportunity to build, expand or refurbish eco-friendly fishing grounds. To facilitate this, the scope of project support was expanded after 2015 and an opportunity was prepared for private subsidy projects to grow to a new level in terms of quality and quantity by switching to a public offering project. However, starting in 2017, demand from the private sector will plunge and selected projects will be delayed or the project implementation rate will be lowered. It was a time for subsidy-related laws and systems to be reinforced but private subsidy projects do not temporarily shrink simply due to the increased administrative burden on private subsidy operators on subsidy management. It plans to review the correlation between laws and systems related to the construction of fish farms and suggest ways to enhance the efficiency of implementation so that economic advantages, the biggest advantage of the private subsidy project, can be recovered within the current legal system.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.42 no.5
• /
• pp.449-455
• /
• 2009

In Hansan Geojeman area, 2,050 ha of shellfish growing area has been designated as shellfish production area for export. The main shellfish species from the designated area is oysters. For the sanitary management of the designated area established in Hansan Geojeman area, bacteriological examination of sea water and shellfish at the sampling stations inside and outside of the designated area were performed from January 2006 to December 2008. The range of fecal coliform of 756 sea water samples at 21 stations located in the designated area were <1.8~>1,600 MPN/100mL. And the range of geometric mean and the estimated 90th percentile of fecal coliform were 1.8~2.9 and 2.7~15.8 MPN/100mL, respectively. Sanitary conditions of the current designated area in Hansan Geojeman meets the required standards of the Fisheries Product Quality Control and National Shellfish Sanitation Program (NSSP, USA) criteria for the approved area. Also, the sanitary status of the shellfish harvested from the designated area met the Korean Shellfish Sanitation Program (KSSP) fecal coliform criterion (<230 MPN/100g). And the human pathogen such as Salmonella spp. and Shigella spp. were not detected from the examined shellfish samples.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.54 no.4
• /
• pp.369-376
• /
• 2021

In Korea, fish is a major food source, and sustainable production of fish is critical for the aquaculture industry. Recently, infectious diseases have become an unavoidable problem in aquaculture and have caused serious economic losses. Therefore, there is an urgent need to overcome this challenge to increase productivity in aquaculture. Vaccination is the most effective and long-term measure for improving the management of a fish farm. Sales of fish vaccines in Korea have been steadily increasing, with a confirmed increase from 600 million won in 2007 to 3.4 billion won in 2018. As of 2021, 30 licensed fish vaccines, including both single and combination vaccines containing more than two inactivated pathogens, have been approved in Korea for 10 fish pathogens. Twenty-eight of these are used in olive flounder Paralichthys olivaceus; however, only two vaccines are used in starry flounder Platichthys stellatus, red seabream Ragrus major and rock bream Oplegnathus fasciatus. Therefore, vaccine development is required not only for the olive flounder but also for other cultured fish species. The development of effective vaccines and vaccination programs for fish is a continuous requirement for a sustainable aquaculture industry.

• Journal of Practical Agriculture & Fisheries Research
• /
• v.21 no.1
• /
• pp.149-157
• /
• 2019

This study interested on management of broodstock and the effect of raise the temperature for promotion of maturity in Tresus keenae. For management of broodstock, we performed indoor and outdoor culture. In addition, broodstock was put in exposure and immersion condition. This experimental design is aimed at knowing the optimal management of broodstock. In addition, we investigated the promotion of maturity, growth and survival rate when raise the temperature of the breeding seawater of broodstock in winter season. Result that, the management of broodstock was shown to be more effective obesity and survival rate in outdoor culture than indoor culture. In addition, there is no anthropogenic food supply in management and it is easy to management because it is kept under natural environmental conditions. Therefore, It is considered appropriate to management to outdoor culture. In raise the temperature, survival rate was lower in the experimental group than in the control group. However, obesity was significantly increased compared with the control group. Also, gonad showed that the sex maturity was promoted. If sex maturation is not developed due to seasonal water temperature, the promotion of sexual maturity through heating is considered to be an effective method in terms of artificial seed production.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.60 no.2
• /
• pp.186-193
• /
• 2024

Most fishing nets used in fish cage aquaculture are made of synthetic fibers such as polyamide (PA) and polyethylene (PE). Therefore, it is challenging to maintain the internal volume of the fish cage due to biofouling, which can increase the load on the cage or reduce dissolved oxygen levels by impeding smooth current flow. To address this issue, research has been conducted to replace conventional synthetic fiber cage nets with brass nets, demonstrating certain benefits such as improved productivity and ease of fish cage management. However, given the need for a more thorough examination of brass fishing net weaving technology and performance, this study assessed the optimal weaving method for brass fishing nets to be used in fish cages. Additionally, it provided essential data for the practical application of brass fishing nets by evaluating their weight, tensile strength, elongation, fatigue resistance, and wear resistance. The study concluded that weaving brass fishing nets using the chain link method ensures durability, ease of installation, and compact storage in a scroll-like form. Moreover, due to their superior fatigue and wear resistance properties, brass nets can offer increased utility if appropriate net diameter and length are selected to compensate for their higher weight per unit area and relatively higher cost compared to existing fiber fishing nets.

• Journal of Aquaculture
• /
• v.15 no.1
• /
• pp.49-60
• /
• 2002

Research on practices for improving water quality in channel catfish Ictalurus punctatus ponds was conducted at the Auburn University Fisheries Research Station, Auburn, Alabama, in 1998 and 1999. The objective of this two-year study was to determine better management practices to enhance water quality and improve production efficiency. In the first year, oxidation of bottom soil by drying, tilling, and applying sodium nitrate was performed (dry-till and dry-till with sodium nitrate treatments). The second year, based on the results obtained during the first year, precipitation of phosphorus (P) from water by applying gypsum was compared to the dry-till treatment (dry-till and dry-till with gypsum treatments). Control ponds were not subjected to bottom drying, tilling, sodium nitrate, or gypsum treatment. Channel catfish fingerings were stocked at 15,000/ha. In the first year, water in ponds from dry-till and dry-till with sodium nitrate treatments had lower concentrations (P < 0.01) of soluble reactive P, nitrate ($NO_{3} ^{-}) and nitrite ($NO_{2} ^{-}) nitrogen (N), total ammonia ($NH_3$) nitrogen, total suspended solids and turbidity, and higher values of pH, Secchi disk visibility, total alkalinity, total hardness, and calcium ($Ca^{2+}) hardness than water in control ponds. Ponds of the dry-till treatment also had lower concentrations (P < 0.01) of total P and total N than control ponds. Total fish production and survival rate did not differ among the treatments (P > 0.05). The findings suggested that drying and tiling pond bosoms between crops could achieve water quality improvement. Applying sodium nitrate to dry, tilled pond bosoms did not provide water quality improvement. In the second year, the treatment with the best results from the first year, dry-till, was compared with a dry-till with gypsum treatment. Enough gypsum was applied to give a total hardness of about 200 mg/L, and gypsum was reapplied as needed to maintain the hardness. Compared to the control, dry-till and dry-till with gypsum treatments had lower concentrations (P < 0.01) of total and soluble reactive P, total N, and total $NH_3$-N, and higher concentrations (P < 0.01) of dissolved oxygen. Ponds of the duty-till with gypsum treatment also had lower concentrations (P < 0.01) of chlorophyll $\alpha$, chemical oxygen demand, and total alkalinity than the control. Total fish production and survival rate did not differ (P > 0.05) among the treatments. These findings suggest that drying and tilling pond bosoms between crops and treating low hardness waters with gypsum could achieve water Quality improvement.