• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.3
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• pp.343-350
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• 2016

The sea cucumber Apostichopus japonicus is a commercially valuable aquaculture species in Korea. Aquaculture species require specific nursery culture conditions to increase survival and growth rates. Sea cucumbers hibernate during the high temperatures of summer and during the low temperatures of winter, and suboptimal temperature conditions decrease sea cucumber growth and survival rates. The natural South Korean environment is very unfavorable for culturing sea cucumber; therefore, developing a recirculating aquaculture system (RAS) capable of breeding and growing sea cucumber year-round is necessary. The aim of this study was to investigate growth performance of juvenile sea cucumber in a RAS. Growth and survival rates of juvenile sea cucumber were high during our 24-week experiment. Sea cucumber survival rates were 87.8-93.3%, and specific growth rates were 0.4689-0.7846.

• The Journal of Fisheries Business Administration
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• v.44 no.3
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• pp.77-84
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• 2013

While some steps in laver aquaculture production can be controlled artificially to a certain extent, the culturing process is largely affected by natural factors, such as the characteristics of seawater, climatic and oceanographic conditions, etc. This study aims to find a direct relationship between climatic and oceanographic factors (water temperature, air temperature, salinity, rainfall, sunshine duration and wind speed) and laver aquaculture production in Wando region, the biggest aquaculture production area of laver, located in the southwest coast of Korea using a multiple regression analysis. Despite the small sample size of a dependent variable, the goodness of model fit appeared acceptable. In addition, the R-squared value was 0.951, which means that the variables were very explanatory. Model results indicated that duration of sunshine, temperature, and rainfall during the farming period from the end of September to the end of April would be important factors affecting significantly to the laver aquaculture production.

• Fisheries and Aquatic Sciences
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• v.25 no.8
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• pp.429-440
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• 2022

This study assessed the effects of oxygen and ozone nanobubbles on gill morphology, weight gain, and mortality of Pacific white shrimp (Penaeus vannamei), as well as the level of Vibrio parahaemolyticus and water quality of shrimp culture tanks under lab conditions. Two experiments were carried out with oxygen macrobubble, ozone macrobubble, oxygen nanobubble, ozone nanobubble, and control treatments (air-stone macrobubble). Experiments were done in triplicate in 100 L tanks with 15‰ saline water, and 20 shrimp per tank. Tanks in Experiment 1 were not inoculated with bacteria; tanks in Experiment 2 were inoculated with V. parahaemolyticus at a concentration of 10⁶ CFU/mL. The results revealed that short treatments with ozone nanobubbles had minimal impact on shrimp gills, mortality, and growth rates, reduced V. parahaemolyticus concentration in water compared to the other groups, and improve water quality. These laboratory results indicate that ozone nanobubble treatment may be useful for controlling V. parahaemolyticus. More work is needed to find the best protocol to apply the technology on a commercial scale.

• Korean Journal of Ichthyology
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• v.32 no.4
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• pp.232-238
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• 2020

The objective of the present study was to investigate fish farm and growth performances of Chinese muddy loach (Misgurnus mizolepis) under indoor and outdoor aquaculture conditions for the domestic loach aquaculture industry. The investigation was conducted from August 2017 to October 2019 at one indoor farm (D-site) and two outdoor farms (P1-site and P2-site). Results showed that WG (weight gain), DWG (daily weight gain), and SWG (specific weight gain) based on growth measurements were 175.27±36.2%, 7.98±3.3%, and 0.94±0.2% at D-site, 320±34%, 4.07±0.6%, and 0.55±0.1% at P1-site, and 295.9±53%, 4.15±0.5%, and 0.62±0.1% at P2-site, respectively. WG was higher in outdoor farms (P1-site and P2-site), while DWG and SWG were higher in the indoor farm (D-site). Such differences of the present study might be due to differences in growth, water quality, plant and sale frequency depending on aquaculture types. In particular, outdoor farms takes more than a year to have sales whereas indoor farms can have sales three times in a year.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.6
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• pp.675-681
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• 2013

There have been many studies on biofilter process regarding satisfactory water quality and the operational conditions of Recirculating Aquaculture Systems (RAS). For effective nitrification processes, it is necessary to dynamically identify and apply nitrifying microorganisms. Physical, chemical and biological processes concerning biofilms can be applied and influential factors including substrate, dissolved oxygen concentrations, organic matter, temperature, pH, alkalinity, salinity and mixing velocity intensity need to be considered. Also, designing and managing the process based on the dynamic interpretation of these factors are prerequisites for engineering applications of the biofilter process. This paper draws on current literature on the kinetics of nitrification of biofilms in the biofilter process. Influential factors for nitrification are crucial during the biofilter process and are expected to be critical in informing the design and operation of recirculating aquaculture systems.

• ALGAE
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• v.32 no.1
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• pp.1-13
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• 2017

Seaweed aquaculture technologies have developed dramatically over the past 70 years mostly in Asia and more recently in Americas and Europe. However, there are still many challenges to overcome with respect to the science and to social acceptability. The challenges include the development of strains with thermo-tolerance, disease resistance, fast growth, high concentration of desired molecules, the reduction of fouling organisms and the development of more robust and cost efficient farm systems that can withstand storm events in offshore environments. It is also important to note that seaweed aquaculture provides ecosystem services, which improve conditions of the coastal waters for the benefit of other living organisms and the environment. The ecosystem services role of seaweed aquaculture and its economic value will also be quantitatively estimated in this review.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.59 no.2
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• pp.181-187
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• 2023

Laver aquaculture, which occupies a large proportion in the aquaculture industry in Korea, is still highly dependent on human labor. Therefore, it is necessary to study the development of an automatic system to improve the working environment and increase the efficiency of aquaculture production systems. The purpose of this study is to evaluate the economic feasibility of an improved system in a study for the loading-unloading and automatic weighing systems in laver aquaculture industry. Economic analysis of the developed unloading and automatic weighing system were implemented under various conditions to calculate more accurate benefits and costs. As a result of this study, the economic feasibility was found to be very high in the three models: net present value (NPV), benefit-cost ratio (B/C), internal rate of return (IRR). Moreover, the results of sensitivity analysis showed that the economical efficiency of the automatic loading, unloading, and weighing system in laver aquaculture was very high.

• The Journal of Fisheries Business Administration
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• v.54 no.4
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• pp.47-64
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• 2023

The development potential of the aquaculture industry is very high, but there is no financial support for investment except for the government, policy funds, fishery funds, etc. Therefore, we would like to propose a contract transaction in the aquaculture industry. This refers to a forward contract between a producer (fish farmer) and a buyer (mainly a processor or marketer) that stipulates the production and supply of fish products at a predetermined price, but it also refers to an "equity participation type" contract in which both producers and buyers can participate. In other words, it is a model in which part of the fish farm is produced in a way that meets the conditions of the buyer, and part is produced by the producer. This study aims to establish the basic contract trading process. It provides an academic approach to prevent adverse selection and moral hazard due to information asymmetry. It also provides an idea to converge the aquaculture industry with the financial industry using Pecking Order theory. By doing so, we have made it possible for venture capitalists to invest with confidence and provided a process for investors to resolve their concerns, paving the way for the aquaculture industry and the financial industry to develop together.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.2
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• pp.73-78
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• 2007

The suitability of a flexible fiber filter for removing suspended solid (SS) in a recirculating aquaculture system was evaluated. This study focused on variation in the performance with a change in filtering time, influent water quality, and filtering mode duration. The particle distribution diagram of the filter effluent showed that the number of particles bigger than $5-8{\mu}m$ decreased dramatically, and the removal efficiency exceeded 80%. Although the removal efficiencies of SS and chemical oxygen demand (COD) were dependent on the quality of the influent, the SS and COD concentrations of the effluent were not affected by the influent concentrations. This was despite the deterioration if water quality after feeding in the rearing tank. The performance of the filter was not affected by the filtering mode duration, feeding conditions, or filtering time. The SS concentration and turbidity of the recirculating-type rearing tank were 30% and 50% lower, respectively, than of the a non-recirculating-type rearing tank under the same operating conditions. The flexible fiber filter was applicable to a recirculating aquaculture system that uses plenty of seawater, based on its low filtering resistance $(2kg_f/cm^2)$, high flux $(330m^3/m^2/hr)$, and high fine particle removal efficiency (80%, $5-8{\mu}m$).

• The Korean Journal of Mycology
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• v.50 no.3
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• pp.161-171
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• 2022

The edible paddy straw mushroom Volvariella volvacea (Bull. ex F.) Singer has high nutritional and medicinal values. They are grown on a wide variety of agricultural by-products using different several methods. The result of this present study showed that type of bed and cultivation condition (outdoor/indoor) had effects on the yield of paddy straw mushrooms grown on the spent oyster mushroom sawdust. The treatment of circular compact bed under indoor cultivation condition (CYIC) had the best yield and biological efficiency (B.E.) with 2,119.2 g/bed and 14.5%, respectively, followed by the treatment of conventional bed under outdoor cultivation condition (COOC) with the yield and B.E. of 1,935.5 g/bed and 13.2%, respectively, but the lowest yield and B.E. were observed in the treatment of conventional bed under indoor cultivation condition (COIC) with 1,226.1 g/bed and 8.4%, respectively. Paddy straw mushrooms cultivated on spent oyster mushroom sawdust should be proper in both outdoor and indoor conditions by conventional and circular compact methods as well. However, in indoor conditions, paddy straw mushrooms should be grown in a circular compact bed to ensure the temperature of the bed is suitable for the mushroom growth.