• 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.

• Ocean and Polar Research
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• v.27 no.3
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• pp.323-333
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• 2005

The paper is to serve as a guide for deciding on a desirable direction for the vessel buyback program, reviewing their performance and economic effects from fish harvest reduction due to not reaching MSY. Compared with maximum willingness to pay for vessel buyback programs designed to avoid economic losses occurring as a result of overfishing, the portions of investment costs for buyback program are so small comparatively to the range of 0.32% to 12.19% at the annual base. The economic loss effects occurred in terms of the reduction of fishing harvest are comprehensively estimated at the present value of 30,877 billion won since 1971, and exceeded the revenues for fish harvests from 1999. In order to resole fish stocks through a vessel buyback program, this paper recommends that the yield should be reduced to less than the intrinsic growth rate. Otherwise, the buyback program policy eventually fails regardless of the temporal effect of benefits. This paper further argues that technical policy tools such as fishing grounds, fishing seasons, size of fish and minimum size of meshes should be effectively utilized.

• Journal of fish pathology
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• v.28 no.3
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• pp.165-169
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• 2015

Occurrence of Scuticociliatosis in olive flounder farm of Jeju was monitored from 2007 to 2014. As a result, 23.8~36.4% of referred samples were diagnosed as Scuticociliatosis. Based on fish size, the highest incidence (50.5%) was found in fish with size of 10~20 cm.

• Journal of Aquaculture
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• v.12 no.2
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• pp.137-143
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• 1999

The effects of dietary protein level on growth, feed utlization and liver size were studied with juvenile haddock (Melanogrammus aeglefinus) of 6.88$\pm$0.54 g (mean$\pm$SD). Five isoenergetic diets containing 44.4 to 64.7% protein were fed to triplicate groups of 50 fish in a flow-through system for 6 weeks. All fish showed a relative increase of more than 300% in final weight. There were, however, no significant differences (P>0.05) in weight gain (16.1 to 17.3 g) and specific growth rate (2.9 to 3.0) among fish groups. A higher protein diets resulted in a lower feed intake. Feed: gain ratio linearly improved (P<0.05) when protein level increased from 44.4 to 59.7%. The lowest protein efficiency ratio was observed in fish fed the highest protein diet. Hepatosomatic index of fish significantly decreased from 10.7 to 7.3% with an increase in protein level. Results from this study suggest that haddock could grow well even when fed the diet with protein lower than 44.4%.

• Korean Journal of Ecology and Environment
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• v.53 no.2
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• pp.156-164
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• 2020

The accurate estimation of fish assemblages is highly dependent on the sampling gear used for sampling. We used data from 15 sampling sites along the Nakdong River, which is a large river in South Korea, to identify differences in assemblages and sizes of freshwater fishes collected with either cast nets or gill nets, the two most commonly used sampling gear in South Korea. The two gears differed in the fish assemblages they captured, with more species caught by gill nets. Further, due to its tighter mesh size, the cast net caught significantly smaller fishes than the gill nets(independent t-test, p<0.05). We found the cast net to be appropriate for species that inhabit shallow (less than 2 m) and open water, but inappropriate for deep water, habitats with plant beds, and nocturnal species. Thus, cast net sampling is not efficient in a large river environment, and a combination of sampling methods is more suitable for understanding fish assemblages in such habitats. In general, appropriate selection of fishing methods to specific habitats is necessary to improve data quality and minimize the misrepresentation of environmental conditions.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.3
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• pp.197-201
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• 2004

Juveniles of parrot fish (Oplegnathus fasciatus) were graded and divided into three groups (mean initial size): Small group $(32.9\pm3.2\;g),$ Large group $(130.1\pm12.3\;g)$ and Ungraded group $(74.8\pm29.8\;g).$ Growth and sex ratio were monitored over 3 years. It was concluded that no production advantage was gained by weight grading. There were no differences when the pooled data from the two graded groups were compared with the ungraded group, although mean weight and survival of the large group were continuously higher than those of other groups until the end of rearing period. The highest percentage of males was found in the large group. These results show that males start growing faster than females long before the size grading.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.6
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• pp.719-724
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• 2019

This study is an extension of our previous model for a size-based fish stock assessment. In the previous model, we applied an allometric length-weight relationship (W=α·L^β) to convert lengths of fish to weights, and estimated those parameters α and β, using data about lengths and weights aggregated over years. In this study, we focused on whether consideration of temporal (e.g., year-to-year) variability in those estimates (i.e., ${\hat{\alpha}}$ and ${\hat{\beta}}$) would contributive. After calculating year-specific estimates (i.e., year-specific pairs of ${\hat{\alpha}}$ and ${\hat{\beta}}$) by applying data about lengths and weights separated by year, we evaluated the contribution of those year-specific pairs of ${\hat{\alpha}}$ and ${\hat{\beta}}$ to the performance of the size-based stock assessment model. The model with such year-to-year variability being considered (lower AIC) outperformed that with the variability being ignored (higher AIC). We illustrated this study using data on Korean chub mackerel Scomber japonicus from 2005-2017.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.1
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• pp.35-41
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• 2006

The feeding habits of Spanish mackerel (Scomberomorus niphonius) were studied based on the examination of stomach contents of 445 specimens collected from January to December 2004, in the Southern Sea of Korea. The size of Spanish mackerel ranged from 26.1 to 105.4 cm in fork length (FL). Spanish mackerel was a piscivorous fish which mainly consumed teleost fishes such as chub mackerel (Scomber japonicus) and anchovy (Engraulis japonicus). Its diet also included small quantities of shrimps, stomatopods, cephalopods, crabs, polychaetes, amphipods, cumaceans and copepods. Smaller individuals (<60 cm FL) consumed small fishes such as Engraulis japonicus and crustaceans. The portion of these prey items decreased with increasing fish size, and this decrease was paralleled with increased consumption of lager fishes such as Scomber japonicus and Cololabis saira. The prey size increased with the increase of fish size.

• Journal of Ecology and Environment
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• v.38 no.3
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• pp.383-388
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• 2015

Reservoirs consist of two different environments, the littoral and the pelagic zone, and different fishing gear is commonly used in each zone-gill nets in the pelagic zone and electrofishing in the littoral zone. However, an active fishing gear, the cast net, is normally used instead of electrofishing for scientific studies in South Korea. In order to estimate cast net effectiveness for determining fish status in reservoirs, the study was conducted at 15 reservoirs with two different fishing gears: a cast net in the littoral zone and gill nets in the pelagic zone. When combining catches of both gears, species richness increased substantially compared to using one gear only. There was a size difference in fish caught by each net, and small fish were predominantly caught with the cast net due to its small mesh size (7 mm). The combined length of six species, used for length-weight relationship analysis, collected with the cast net was smaller than that collected with gill nets (independent t-test, P < 0.05). In this study, cast net sampling provided sufficient data for the littoral zone, but not enough to identify the overall fish assemblage in studied reservoirs. Utilization of only one gear can therefore lead to substantial underestimation of fish status, and a combination of both gears is recommended for determining more reliable estimates of fish status in reservoirs.

• Journal of the Korean Statistical Society
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• v.9 no.2
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• pp.213-217
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• 1980

This paper aimed at studying an efficient sampling design of the survey for non-consignment fishery products including both marine fisheries and seaculture. An analysis was done on the relationship between precision and sample size. On the basis of the analysis, the sample size was determined to be 1,080 fishery house holds with the expected precision of 4%-5%. The molluscs and seaculture were recognized to be correlated with the non-consignment products. An attempt was made to investigate the coverage of the fish kinds by the sample about 100 fish kinds were found in the 80 selected sample villages, whereas the population includes about 120 in total. This shows that the sample represents the population with satisfaction.