• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.17-18
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• 2003

Although flounder is one of the most important marine fish for aquaculture in Korea, feeding the flounder in commercial farms depends mainly on moist pellet in which over 70% frozen fishes (e.g. frozen horse mackerel) are incorporated in its formulation. Therefore, for further expansion of flounder farming, it is essential to employ practical formulated feeds that can support reasonable growth. Development of nutritionally balanced and cost-effective feeds is dependant on the information about nutritional requirement and feed utilization of the species. Nutrient and energy source in feed are needed for the growth and maintenance of fish. Protein is probably the most important nutrient affecting fish growth and feed cost. Therefore, it is essential to determine the optimum dietary protein level for the growth of fish, both its high proportion in the feed and because it is the main factor in determining feed cost. Dietary energy level is also critical because protein source in the feed is utilized as an energy source when the feed deficient in energy is fed to fish, whereas when the feed excess in energy is fed to fish, feed consumption decreased and resulted in growth reduction due to lack of other necessary nutrients for normal growth. Improper dietary protein, energy levels and/or their ratio will lead to an increase of fish production cost and deterioration of water quality resulting from wasted feed; thus, they are important in formulating commercial feed. Dietary lipids play important roles in providing energy and essential fatty acid for normal growth and survival of fish. Although carbohydrates are not essential nutrients for carnivorous fish, these compounds play important roles as a low-cost energy source for protein sparing and also as a feed binder. Nutrition researches for flounder have identified its requirements of protein, lipid and essential fatty acid, vitamin, and minerals for normal growth. Other studies have also been carried out to investigate the utilization of the protein, lipid and carbohydrate sources. Based on these nutritional information obtained, practical feed formulations have been studied for improve aquaculture production of flounder. The results of the researches on utilization of dietary protein, lipid and carbohydrate by flounder are discussed in this review.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.4
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• pp.377-383
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• 2013

We ran a feeding trial to determine optimal dietary protein and lipid levels for growth of juvenile long snout bullhead Leiocassis longirostris Gunther. Eight experimental diets (P20L7, P20L14, P30L7, P30L14, P40L7, P40L14, P50L7 and P50L14) were formulated to contain 20%, 30%, 40% or 50% protein combined with either 7% or 14% lipid. Three replicate groups of fish (mean mass: 3.9 g/fish) were fed one of the experimental diets ad libitum for 8 weeks. Survival of fish fed the P20L14 diet was lower than that of fish fed the P40L14, P50L7 and P50L14 diets. Growth of fish fed diets containing 7% lipid increased with increasing protein level (up to 50% protein); growth of fish fed diets containing 14% lipid increased with increasing protein level (up to 30% protein). The feed efficiency of fish fed a diet with 50% protein and 7% lipid was higher than that of other groups. Whole body moisture and lipid contents were affected by dietary lipid level but not by dietary protein level. The crude lipid contents of fish fed 14% lipid diets were higher than those fed 7% lipid diets across all protein levels (other than the 50% level). Thus, under our experimental conditions, an increase in dietary protein level improved growth and feed efficiency of fish; a diet containing 50% protein with 7% lipid was optimal for growth and effective feed utilization in juvenile long snout bullhead.

• Journal of Marine Bioscience and Biotechnology
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• v.3 no.1
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• pp.7-12
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• 2008

Cameroon is a country in Western Africa with 16 million inhabitants. Located between Nigeria and Equatorial Guinea, the country is bordered by the Bight of Biafra. It has a 402 km long coastline. It covers an area of about 475,440 sq km. Cameroon obtains its fish supply from five distinct sources notably-small scale maritime Fisheries, inland fisheries, industrial fisheries, aquaculture and importation. Despite its enormous potential, Cameroon produces only 180,000 metric tons fish annually. The total artisanal annual catch is estimated to be 55,000 t of which bonga/Sardinella, white shrimp and demersal fish contribute 58%, 27% and 15% respectively. The industrial fleet expanded rapidly during the sixties and by 1973 there were 29 trawlers and 13 shrimpers which landed a total of about 17,600 t of fish and shrimp. The total catch of the industrial fisheries peaked at about 20,400 t in 1976 and since then catches have generally declined. The per capita fish consumption in Cameroon stands at about 17.9 kg per inhabitant per year. This means that the demand of fish in Cameroon stands at about 280,000 tons. There is a deficit of in fish supply for which the government always resort to massive importation of fish products to meet the local demand. The main fish product for export from Cameroon is the prawn (Panacus duorarum). The main export market of Cameroon's prawn is the European Union (EU). Between 1998 and 2003, Cameroon's export value has been on the decline, dropping from 1,836 metric tons of prawns for a value of 264 millions USD in 1998 to 51 tonnes, for an estimated value of 315,000 USD in 2003. This drastic drop in exportation is consequential to Cameroon's auto suspension from the exportation of prawns towards the EU as a result of non compliance with EU standards. Today, a good quantity of the catches is being exported illicitly through neighbouring countries.

• Proceedings of the Korean Aquaculture Society Conference
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• 2002.10a
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• pp.35-36
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• 2002

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.4
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• pp.427-434
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• 2014

Although ex situ target strength (TS) measurements using dual- and split-beam systems have become the primary approach of estimating fish abundance, theoretical model estimation is a powerful tool for verifying the measurements, as well as for providing values when making direct measurements is difficult. TS values for 20 samples of live bambooleaf wrasse (Pseudolabrus japonicus) whose target length (TL) ranged between 13.7 and 21.3 cm were estimated theoretically using the Kirchhoff-ray mode model, and the TS values for 18 live fish samples were additionally measured at ${\sim}0^{\circ}$ tilt angle to the swimming aspect using a tethered method at a frequency of 120 kHz to verify the theoretical values. The digitizing intervals used to extract the fish body and swim bladder morphology in the X-ray photographs significantly affected the calculated TS patterns, but variations based on the speed of sound and density ratio values for the general range of fish flesh were relatively small (within 1 dB). Close agreement was observed between the measured and theoretical TS values, and the correlation between the average TS and body length of the fish could be calculated accurately as <$TS_{120kHz}$>= 20logTL (cm) -71.6 using the theoretical method.

• Journal of fish pathology
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• v.6 no.2
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• pp.197-204
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• 1993

Flounder culture has been developed mainly in the western parts of japan, and, to date, following six bacterial diseases have been reported. Bacterial white enteritis occurs in 16 to 30-day-old flounder larvae and often causes mass mortality in seed production. Bacterium named Vibrio sp. INFL invades and multiplies in the mucosae of posterier part of intestine, and causes desquamative enteritis. Gliding bacterial disease occurs mostly in juvenile stage and in spring to summer. Diseased signs are partial discoloration and erosion of skin and fins. Histologically, epidermis are removed, and the causative bacterium, Flexibacter maritimus, multiplies on the surface of demis and invades into the muscular tissue. Vibriosis caused by Vibrio anguillarum and related organisum is one of the well-known diseases among marine fish. Outbreaks of the disease in flounder culture are relatively few, but mass mortalities in fingerlings due to the disease were reported. An outbreak of nocardiosis in the autumn of 1984 has been reported, but since then the disease scarcely occurred. The disease is characterized by formation of abscesses under the skin and white nodes in the gill, heart, spleen and kidney. Streptococcicosis occurs frequently in recent years. Beta-hemolytic streptococcus is the causative bacterium, which possesses the same biochemical and serological characteristics as $\beta$-streptococci isolated from some marine and freshwater fish, and is seemed to related to Streptococcus iniae. Edwardsiellosis is the disease that causes most damage in flounder culture in Japan. Characteristic symptoms are swelling of abdomen and intestinal protrusion from the anus due to accumulation of ascites. Edwardsiella tarda, a well-known pathogen of freshwater fish, is the causative bacterium of the disease.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.5
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• pp.645-653
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• 2014

We examined seasonal variation in fish species composition in coastal waters near Wolseong Nuclear Power Plant in the East Sea of Korea. A total of 72 species, 39 families, 14 orders, 46,214 individuals, and 4,639,667 g were collected. Glyptocephalus stelleri was the most dominant species by number of individuals (35%), followed by Clupea pallasii (26%). Liparis tanakai and Lophius litulon were the dominant species by biomass, accounting for 46% and 28%, respectively. We showed that bottom salinity and temperature are the most important environmental factors influencing fish species composition. Although bottom salinity did not differ statistically among seasons or stations, we detected some variation among stations. Additionally, bottom temperature differed among seasons and stations (P<0.05), affecting numbers of individuals and biomass. Thus, seasonal variation in fish assemblages can be classified into two groups: spring/summer and autumn/winter.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.1
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• pp.253-261
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• 2015

The chemical water quality and fish assemblage of Dong Stream to assessment of environmental improvement after discharge seawater were investigated from July to December 2013. BOD and DO were significantly different between before and after discharge seawater, while pH and SS did not significant. A total of 11 fish species, 218 individuals and 10,525.1g were collected. Dominant fish species were Mugil cephalus, Konosirus punctatus, Acanthogobius flavimanus and Leiognathus nuchalis which account for 77.5% of total individuals collected, and they were estuarian species. Peak number of species and individuals, and biomass occurred in September, whereas diversity index were highest in November. The water ecosystem of Dong Stream have been changed estuarian environment. As a result of stream assessment on water quality and ecosystem, water quality have been improved as 'III' grade. These results suggested that stream restoration policies such as drain pipes maintenance, management of pollution sources and riverbed dredging to improve environment and recover habitate of Dong Stream were need for set up and establishment of regular monitoring system.

• Journal of Aquaculture
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• v.20 no.2
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• pp.132-139
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• 2007

A four-week feeding trial was conducted to investigate the effects of dietary soybean meal (SBM) and powdered Cheongkukjang (CKJ) on non-specific immune responses of parrotfish Oplegnathus fasciatus. Three isonitrogenous (42% crude protein) and isocaloric (17.1 MJ/kg) diets were formulated to replace fish meal by 0, 25% SBM or 25% CKJ (designated as FM, 25SBM and 25CKJ, respectively). Ninety fish (initial body weight 122 g) were randomly allotted into nine 150 L tanks. One of the three experimental diets was fed to triplicate groups of fish for 4 weeks. After the feeding trial, no differences were observed in growth performances and feed utilization among fish groups. Liver superoxide dismutase activity of the fish fed CKJ containing diet was significantly higher than that of the control groups. DPPH radical scavenging and $Fe^{2+}-chelating$ activities of the experimental diets containing SBM or powdered CKJ were significantly higher than that of the control diet. The results of the present study suggest that dietary inclusion of powdered 25CKJ significantly increased liver superoxide dismutase activity and did not affect the growth performances, feed utilization, morphological parameters, as well as hematological values of parrotfish.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.5
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• pp.619-625
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• 2013

We investigated yearly fluctuation of the fish species composition of beam trawls off Maemuldo in the east southern sea of Korea, from March 2007 to November 2009. A total of 75 fish species were collected during the period. The number of fish species accumulated amounted to 54, 64 and 75 species in 2007, 2008 and 2009, respectively. The number of newly occurring species increased with time. The number of expected resident species in Maemuldo was estimated as 9 species including Conger myrister, Okamejei kenojei and Pholis nebulosa, each of which appeared more than 14 out of a total 27 times. Cluster analysis showed that the years 2007 and 2008 were closely clustered, while the year 2009 was distantly clustered with 2007 and 2008. This may be due to the high catch ratio of Clidoderma asperrimum in 2009 alone, when a low water temperature phenomenon was observed unlike the situation in 2007 and 2008.