• Korean Journal of Ichthyology
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• v.20 no.4
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• pp.303-312
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• 2008

Seasonal variation in species composition and abundance of fishes was determined using monthly samples collected by a fyke net in coastal waters off Namhae Island in 2006. The sampling gear, both-side fyke net, is a widely used commercial fishing gear in shallow waters of the region. A total of 89 fish species was collected, the dominant species were Konosirus punctatus, Mugil cephalus, Lateolabrax japonicus, Acanthopagrus schlegeli, Sebastes inermis, Nibea mitsukurii, Clupeapallasii, Pampus echinogaster, Sebastes schlegeli and Limanda yokohamae. They accounted for 61.1% of the total number of individuals and 80.3% of the biomass. The dominant species were primarily composed of small individuals or juveniles of large-sized fishes. Abundance in the number of individuals and biomass showed peaks in April, May and September, and was lowest in January. Temporal change in fish abundance was related to the temperature and related factors.

• Korean Journal of Ichthyology
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• v.28 no.4
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• pp.249-259
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• 2016

Monthly variation in species composition was determined using fish samples collected by a beach seine between October 2013 and September 2014 in the eelgrass bed in Aenggang Bay, Namhae, Gyeongsangnamdo. A total of 3,174 individuals of 35 species, amounting to 3,137 g were collected. The dominant species was Gymnogobius heptacanthus, followed by Pholis nebulosa, Rudarius ercodes, Favonigobius gymnauchen and Hypodytes rubripinnis. Almost all fish collected were small in size or juveniles. Seasonal variation of species composition showed that the dominant species, used the shallow area of the eelgrass bed as a nursery ground and moved to a deeper water as they grew. Saurida elongata, Inimicus japonicus, Sphyraena pinguis, and Arothron hispidus, were first reported in an eelgrass bed in the southern coastal water.

• Ocean and Polar Research
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• v.43 no.2
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• pp.89-98
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• 2021

The seagrass habitats are a highly productive marine ecosystem which provides nursery ground and shelter for many fish and invertebrate species. Pholis nebulosa (Temminck & Schlegel, 1845) is one of the most abundant seagrass fishes in the coastal waters of Korea. The estimation of fish production is key for devising conservation measures and ensuring fish resources sustainability. A total 894 P. nebulosa ranging from 3.83 to 26.5 cm total length (TL) were collected monthly in 2006 with a small beam trawl in a seagrass bed of southern Korea. Growth parameters of P. nebulosa were estimated using the von Bertalanffy growth model, and production was estimated using a general equation which relates daily fish production to ash-free dry weight (AFDW), biomass, and water temperature. The von Bertalanffy's growth equation was estimated as: L_t = 28.3823(1-e^{-0.7835(t+0.9864)}). The densities, biomass, daily, annual production, and P/B ratio were 0.069±0.061/m^-2, 1.022±0.621 g/m², 0.005±0.004 g AFDW/m²/day, 1.676 g AFDW/m²/yr, and 1.641, respectively. Monthly variation in production of P. nebulosa peaked during March and April 2006 (0.0139 and 0.0111 g AFDW/m²/day), whereas the lowest value of 0.0005 g AFDW/m²/day was in December. Monthly change in production of P. nebulosa was positively correlated with biomass and condition factor. Our results will contribute to the conservation of seagrass ecosystems, which are still undisturbed in the study area.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.54 no.4
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• pp.324-332
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• 2018

We conducted a questionnaire survey to analyze the current status of the coastal composite fisheries, as well as the improvement point in designing a new type coastal composite fishing boat suitable for Korean fishing environments from April to August 2017. The questionnaire composed of 20 questions about the features of the coastal composite fishing boat and fishing work. The survey sites were selected to cover all parts of the country by considering the geographical position. The significance testing for the response results was accessed by ${\chi}^2$ test and ANOVA. The results revealed that more than half (59.1%) of the fishermen operated one day per voyage and operating alone topped with 22.5% in the number of crews, followed by 2 persons (20.3%) and 5 persons (22.1%). The navigation devices had a high rate of installation and GPS plotter ranked first in the devices. In addition, fish finder ranked first in fishing equipment, followed by net hauler. The most inconvenient work that they felt during the fishing operation was fish handing at 49.8% and other general fishing works like setting and hauling line, deck cleaning accounted for about 25%. The hardest work was the accident by ropes wrapped around propeller and the engine trouble came in second. The most inconvenient facilities to the present design of fishing boat was wheelhouse (76.7%), followed by fish hold (38.5%), and deck (35.1%). Furthermore, inconvenient points related to the movement of fishing gear, noise and vibration of engine, slippery deck and small fish hold exceeded 50%.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.3
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• pp.247-255
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• 2019

This study was conducted to investigate the effects of extrusion pressure and particle size of feed ingredients on the growth performance and plasma hormone activity in juvenile olive flounder Paralichthys olivaceus. Experimental diets were prepared with extrusion pressure manipulated by screw speed [low pressure (LP), 885 rpm/min; high pressure (HP), 708 rpm/min] and different dietary particle sizes [specific surface area: small (SS), $169.9m^2/kg$; large (LS), $67.4m^2/kg$] in a two-level factorial design. Four experimental diets (LP+SS, LP+LS, HP+SS, and HP+LS) were randomly assigned to 12 tanks (3 replicates) stocked with 20 fish (initial weight, 57 g) per tank. After a 4-week feeding trial, the observable trends of the main effects of extrusion pressure and particle size on growth performance showed that LP and SS enhanced fish weight gain. The plasma insulin-like growth factor-I level was significantly higher in fish fed the LP+SS diet than in fish fed the HP+SS diet. These results indicate that manipulation of the physical qualities of feed through adjustment of extrusion pressure and feed ingredient particle size may influence the growth performance of juvenile olive flounder, which should be considered in feed manufacture.

• Fisheries and Aquatic Sciences
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• v.21 no.11
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• pp.34.1-34.13
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• 2018

Sexual maturity ($L_{50}$), the length at which 50% of fish in a size class are mature, is a key aspect of domestication of new fish species because it guides the procedure for identification of appropriate broodstock size for artificial spawning. In this study, the $L_{50}$ was determined for 1083 Barbus altianalis samples obtained from Lake Edward and the Upper Victoria Nile. Gonads of freshly killed samples were examined macroscopically and verified with standard histological procedures for the maturation stages that were used to determine $L_{50}$. Oocytes and spermatogenic cell sizes were compared for fish obtained from both water bodies. Results indicated that there were no variations in macro gonad features observed for fish from Lake Edward and Upper Victoria Nile. Similarly, there were no significant differences in oocyte sizes (P > 0.05) between the two populations but significant differences in spermatogenic cell sizes were noted (P < 0.05) except for spermatozoa (P > 0.05). This however did not suggest peculiar differences between the two populations for staging the gonads. Consequently, no staging variations were suggested for both populations in determination of $L_{50}$. Sexual maturity was found in the same class size of fork length (FL) 20-24.9 cm and 35-39.9 cm for males and females from both water bodies, respectively. At this FL, however, males were too small, and for good selection of vigor broodstocks for spawning and conservation purposes, they are better picked from class size of 30-34.9 cm FL and above. These findings were crucial for integration of appropriate breeding size in spawning protocol by farmers and fisheries scientists conserving wild B. altianalis populations.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.3
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• pp.239-248
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• 2022

This study was conducted to compare sensory and nutritional and digestive properties of the Israeli carp Cyprinus carpio muscle (ICM) by size [normal large (NLF) and small (NSF) fish], part [ventral (VM) and dorsal (DM) muscle], and commercial value [NLF, recessive (RF) or deformed (DF) fish]. In NLF, the major amino acids were lysine, aspartic acid, and glutamic acid, whereas aspartic acid and glutamic acid were predominant in NSF, DM, VM, DF, and RF. Taurine content increased with fish size, and was higher in DM than in VM, and higher in NLF than in DF but lower than that in RF. Regardless of ICM size, part, and commercial value, potassium and iron were expected in the health function, but calcium and zinc were not expected. The major fatty acids present in ICM were 16:0, 18:1n-9, and 18:2n-6, regardless of size, part, and commercial value. The digestion rate of ICM by digestive organ was lower in NLF than in NSF, and lower in VM with a high lipid content than in DM, and lower in DF than in RF.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.1
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• pp.1-9
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• 2022

This study was conducted to compare the sensory and enzymatic properties of Israeli carp Cyprinus carpio muscle (ICM) according to size [normal large (NLF) and small fish (NSF)], part [ventral (VM) and dorsal muscles (DM)], and commercial value [NLF, recessive (RF), or deformed fish (DF)]. There was not difference in salty of all samples. The sourness was stronger in NLF and DM than in NSF, RF, and DF, and VM, respectively. The umami of ICM showed no size-associated differences; however, those of DM, and DF and RF, were superior to those of the VM and NLF, respectively. The sweetness was also stronger in NLF than in NSF and RF, and in DM than VM. The sweetness of DF didn't differ compared to those of NLF and RF. The intensity of fish odor was weaker in NSF or DF than that in NLF, and was higher in DM than in VM. The color of ICM was bright in NSF and DF compared to NLF. Enzyme activity was very low in the muscles and high in viscera. Therefore, ICM could be used as a material for seafood products, regardless of size, part, and commercial value; however, the issue of lipid oxidation must be considered.

• Journal of Aquaculture
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• v.6 no.1
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• pp.13-27
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• 1993

In order to determine the protein requirements of the Korean rockfish Sebastes schlegeli six isocaloric diets containing crude protein level from 20\%\;to\;60\%$ were fed to two groups of fish, small and large size, with the initial average body weight of 8 g and 220 g respectively. White fish meal was used as a sole protein source. Daily weight gain, daily protein retention. daily energy retention, feed efficiency, protein retention efficiency and energy retention efficiency were significantly affected by the dietary protein content (p< 0.05). The growth parameters (that is, daily weight gain, daily protein retention and daily energy retention) increased up to $44\%$ protein level with no additional response above this point. The protein requirements were determined from daily weight gain using two different mathematical models. Second order polynomial regression analysis showed that maximum daily weight gain occurred at $56.7\%\;and\;50.6\%$ protein levels for the small size group and the large size group, respectively. However the protein requirements, determined by the broken line model, appeared to be about $40\%$ for both groups. Nutrient utilization also suggested that the protein requirements of both groups were close to $40\%$. When daily protein intake was considered, daily protein requirements per 100g of fish, estimated by the broken line model, were 0.99g and 0.35g for the small and large size groups respectively. Based on these results, a $40\%$ dietary crude protein level could be recommended for the optimum growth and efficient nutrient utilization of the Korean rockfish weighing between 8g and 300g.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.15 no.2
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• pp.67-76
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• 1979

Diurnal variation of the catch of some important species groups in the Northwestern coast of Africa were studied on the basis of fish catching data compiled by a stern trawler(G.T., 499ton 2,200ps). The experimental fishing has been conducted from September, 1975 to August, 1976. The catch of the important groups I. e. squid, cuttlefish, octopus, sole fish and sea bream revealed different fluctuation patterns. The results obtained are as follows: 1. The catch of squid caught in daytime(0900-1800) was greater than that caught in night (2100-0600). 2. The catch of cuttle fish caught in daytime was more than that caught in night. In the daytime, large size group(heavier than 300g) was caught dominately during midday (1200-1500) whereas the small size group, lighter than 300g, was caught dominately during the time of sunrise (0600-0900) and sunset (1800-2100). 3. The catch of octopus varied according to the size groups. The large sige group, heavier than 700g, was caught predominately during daytime and the small size group, lighter than 700g, was caught predominately during night. 4. The catch of sole fish caught in night was greater than that caught in daytime. 5. The catch of sea bream and miscellaneous fishes including sardin, jack-mackerel and etc. was greater in daytime.