• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.44 no.3
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• pp.174-183
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• 2008

In order to develop the substitutive materials for natural baits of swimming crab pots, the fluorescent characteristics of the baits were analyzed, and the preference of fluorescent dyes were investigated by the mean entrapped catch number to the pots through the water tank experiments and fishing experiments. On the investigation of fluorescent characteristics by the 5 kinds of baits, mackerel, krill, manila clam, pig's fat and chicken's head which were used in substitutive baits for test in the UV long wave(365nm) area, it showed clear blue fluorescence in the skin of mackerel, shell of krill, manila clam and bill of chicken's head, and green fluorescence in the mackerel s muscle and internals, and yellow fluorescence in the pig's fat and chicken's head. On the investigation of fluorescent characteristics by the bait cages in the UV short wave(254nm) and long wave(365nm) area, it showed each green, red and blue fluorescence in the cylinderical or hexahedral red plastic bait cages which were painted each green, red and blue fluorescence dyes, but it showed yellowish green flourescence in the cylinderical or hexahedral red plastic bait cage which was painted yellow fluorescent dye. On the preference investigation of the fluorescent dyes of swimming crabs by the 5 kinds of the bait cages which were put the mackerel in the non-fluorescent red plastic cage($RF_N$), red, yellow, green and blue fluorescent plastic cages(RF, YF, GF, BF) each, nonfluorescent red plastic cage($RF_N$) was entrapped mean 2.0(6.7%), but blue fluorescent plastic cage(BF) was mean 5.0(16.7%) and it was more 2.5 times comparing to $RF_N$, and red fluorescent cage(RF) was same level and green fluorescent cage(GF) was 50% of catch number comparing to $RF_N$, and yellow fluorescent cage(YF) was entrapped nothing(F 46.324, P < 0.05). On the investigation of the entrapped catch number to the pots which were put the mackerel in the blue fluorescent hexahedral plastic cage(HP) and blue fluorescent silicon mackerel model cage(SM), HP was mean 3.4(11.3%) and it was a little more comparing to SM which was entrapped mean 3.2(10.7%)(t 0.775, P > 0.05). Fishing experiments on the preference investigation of swimming crabs by the pots which were put in the non-fluorescent red plastic cage($RF_N$) and blue fluorescent plastic cage(BF) were conducted 3 times. Mean catching number and weight of $RF_N$ were 71.7 ind.(18.3%) and 16.9kg(64.3%), and those of BF were 93.0 ind.(23.1%) and 19.8kg(64.5%), respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.3
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• pp.243-250
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• 2011

The effects of food, temperature, salinity, and rearing density on the survival and growth of the swimming crab Portunus trituberculatus, were studied. With regard to food, the larval survival rate to zoea IV was the highest (53.9%) in the mixed feed group (rotifers+ Artemia), followed, in order, by the rotifer, commercial feed, and Artemia groups. The growth of young crabs reared on different diets was the highest in group VI. The survival rate to zoea II at 20 to $30^{\circ}C$ ranged between 77.2% and 83.1%, and was the highest for crab I (17.3%) at $25^{\circ}C$. When young crabs were cultured individually at four different temperatures (20, 25, 30, and $35^{\circ}C$), the growth did not differ significantly at 25 to $30^{\circ}C$, but was higher than at $20^{\circ}C$. The survival rate of larvae to crab I was 12.7 and 11.4% at 25 and 28 psu, respectively, while all of the larvae died at 15 psu. For young crabs, there was no significant difference in growth and survival from 20 to 30 psu. The survival rate decreased with increasing rearing density from zoea I to crab I. Each molting cycle took 1 month from crab I to VIII. Subsequently, the interval increased with growth. The mean body weight of crab XV after 24 months was $428.05{\pm}57.63\;g$.

• Proceedings of the Korean Aquaculture Society Conference
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• 2005.05a
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• pp.121-121
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• 2005

• The Journal of Korea Robotics Society
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• v.7 no.4
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• pp.284-291
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• 2012

Recently, development of underwater robot has actively been in progress in the world as ROV(Remotely Operator Vehicle) and AUV(Autonomous Unmmanded Vehicle) style. But KIOST(Korea Institute of Ocean Science and Technology), beginning in 2010, launched the R&D project to develop the robot, dubbed CRABSTER(Crab + (Lob)ster) in a bid to enhance the safety and efficiency of resource exploration. CRABSTER has been designed to be able to walk and swim with its own legs without screws. Among many research subjects regarding CRABSTER, optimal swimming patterns are handled in this paper. In previous studies, drag forces during one period with different values for angle of each joint were derived. However kinematics of real-robot and fluid-dynamics are not considered. We conducted simulations with an optimization algorithm for swimming by considering simplified fluid dynamics in this paper. Drag-coefficients applied to the simulation were approximated values calculated by CFD(Computational Fluid Dynamics : Tecplot 360, ANSYS). In addition, optimized swimming patterns were applied to a real robot. The experiments with the real robot were conducted in circumstances in the water. As a result, when the experiments were carried out in the water, a regular pattern of drag force output came out depending on the movement of the robot. We confirmed the fact that the drag forces from the simulation and the experiment has a high similarity.

• Journal of Fisheries and Marine Sciences Education
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• v.29 no.2
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• pp.422-435
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• 2017

Intermolt periods, growth rates, survival (%) and relative growth of the megalopa larvae of Portunus trituberculatus (Miers, 1876) were studied up to the crab 7th stage for 160 days in the 3 different temperature groups in which each has 60 larvae. The higher the water temperature was the shorter the intermolt period was in each crab stage. In addition, a deviation of intermolt periods was shown as few as the water temperature gets higher. The intermolt period in the 7th crab stage was $29.8{\pm}3.26$ days in the experimental group at the room temperature, $45.2{\pm}3.89$ days at the temperature of $17^{\circ}C$, and $25.6{\pm}2.23$ days at the temperature of $27^{\circ}C$, respectively. The survival (%) of larvae of P. trituberculatus (the crab 7th stage) is the highest in the group at the room temperature: However, they showed 15% at the temperature of $27^{\circ}C$ and 10% at the temperature of $17^{\circ}C$. All the groups were shown the similar relative growth, but significant differences appeared in some comparison. The sizes (mean growth of carapace width) of the crabs in the group at the temperature of $27^{\circ}C$ reached 5.01~25.45 mm length (it is the longest among the groups) from the crab 1th to the crab 7th stage. However, the sizes (mean growth of carapace width) of room temperature were 4.99~22.26 mm and the size of crab in the group at the temperature of $17^{\circ}C$ reached 4.8~17.26 mm, The sizes (mean growth of carapace length) of the crabs in the group at temperature of $27^{\circ}C$ reached 2.88~13.56 mm, However, the size of the crab in the group at the room temperature showed 2.88~12.34 mm, while in the group at temperature of $17^{\circ}C$, their average growth of carapace length were 2.51~8.03 mm. The growth rates of larvae of P. trituberculatus (from the crab 1th to the crab 7th stage) were changed with the increase of the instar stage, however their changes showed irregular.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.59 no.3
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• pp.253-262
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• 2023

To identify sand crab Ovalipes punctatus populations and establish management units for each population, mtDNA COI regions were analyzed. As a result, the clade of O. punctatus in Korea were separated by two with a genetic distance of 0.17-2.08%, and there was no significant difference in the result of pairwise FST values representing genetic differentiation by sampling areas (p > 0.05). Also, no geographical separation found in the distribution of haplotypes and the results of the haplotype network. This result suggests that O. punctatus larvae were dispersed for a long time by the ocean current by suffering meroplanktonic period for 1 month, and increased the gene flow due to the development of the swimming legs for the increase in mobility. Therefore, in the results of mtDNA COI region analysis of O. punctatus in the East Sea, Yellow Sea, South Sea and East China Sea (Ieodo) of Korea, no clear intra-species differentiation was found.

• Journal of Food Hygiene and Safety
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• v.15 no.1
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• pp.1-4
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• 2000

Electron spin resonance (ESR) spectroscopy was used to investigate the effect of irradiation dose on the ESR signal intensity of irradiated crabs and the stability of these radicals under 9 weeks of storage. Swimming and small crabs were irradiated with doses of 0, 1, 3, 5 and 7 kGy using a Co-60 irradiator at ambient temperature. A claw, a walking leg and a cars- pace of the crab pieced and dried were placed in a resonant quart tube within an EPR X-band spectrometer. The irradiated crabs presented an asymmetric absorption in shape at g$_1$=2.002 $\pm$ 0.003 and g$_2$=1.998$\pm$0.005, and were different from the non-irradiated ones. The intensity of the ESR signals was greatest in the claw, intermediate in the carapace and lowest in the walking leg. Samples given low and high doses of irradiation could also be distinguished. The ESR signal after irradiation was stable, even after a 9-week storage.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.5
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• pp.787-795
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• 2001

For the developing natural fisheries flavoring substances using crustacea, the flavor constituents of enzyme hydrolysates from shore swimming crab (crab) and spotted shrimp (shrimp) were investigated. In taste-active compounds of both enzyme hydrolysates, total free amino acid contents of crab and shrimp enzyme hydrolysates were 5,226.7 mg% and 8,757.3 mg%, respectively. The major amino acids were taurine, glutamic acid, proline, asparagine, glycine, alanine, valine, leucine, lysine anserine and arginine. As for ATP related compounds, AMP was the principal component and small amounts of IMP was detected in both enzyme hydrolysates. In the quarternary ammonium bases, betaine was the principal component (593.8mg%), and contents of TMAO and betaine in both samples were 60.7 mg% and 850.0 mg%, 124.1 mg% and 755.9 mg%, respectively. The major components were Na, K, P and Cl in inorganic ions. The major fatty acids of both sample were 14 : 0, 16 : 0, 16 : 1n7, 18 : 1n9, 20 : 5n3 and 22 : 6n3, and composition ration of n3 polyunsaturated fatty acids of were 27.8% and 28.5%, respectively. Total 99~109 volatile compounds were detected as a cooked odor of crab and shrimp enzyme hydrolysates by SDE apparatus/gas chromatography/mass spectrometry. The volatile flavor compounds identified from cooked crab enzyme hydrolysate were composed of 6 acids, 10 alcohols, 7 aldehydes, 11 ketones, 1 ester, 5 phenols, 4 benzenes, 22 hydrocarbons, 1 furan, 21 nitrogen containing compounds and 11 micellaneous compounds. And the volatile flavor compounds indentified from cooked shrimp enzyme hydrolysate were composed of 13 acids, 10 alcohols, 6 aldehydes, 10 ketones, 3 esters, 2 phenols, 5 benzenes, 36 hydrocarbons, 1 furan, 14 nitrogen containing compounds and 8 micellaneous compounds.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.4
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• pp.558-568
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• 2023

The spatio-temporal distribution of the sand crab Ovalipes punctatus larvae was investigated in the Korean waters in 2019. Sea surface temperature (SST) was the lowest in February and highest in September. Sea surface salinity (SSS) was the lowest in September and highest in March. Further, sea surface chlorophyll a (SSC) was the highest in September. Larvae were distributed in the South Sea and coastal area of Jeju Island from April to June, and the abundance was the highest in May. The spatio-temporal distribution analysis suggested that larval groups showed a tendency to be dispersed over a wider area as the larvae developed, due to the increase in their swimming ability. The correlation analysis between environmental factors and larval density suggested that larvae appeared in the SST range 11.8-20.9℃ and SSS range 31.5-35.3 psu. The Megalopal stage appeared in a wider range of SST and SSS than other larval stages, possibly due to the increased environmental tolerance before settlement. Results of redundancy analysis (RDA) and Spearman's rank correlation analysis between the larval density by developmental stages and the environmental factors suggested that SST showed a positive correlation and SSC showed a negative correlation in the later stage.

• Journal of the Korean Applied Science and Technology
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• v.35 no.2
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• pp.367-377
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• 2018

Swimming crab(Ovalipes punctatus) is produced in Korea and utilized as semi-processed food at streamed cooked state. Recently, protein hydrolysates have been known as having function such as antioxidant, suppression of hypertension, immunodulatory, alleviation of pain, and antimicrobial activity. This research was investigated to find the functional antioxidant from crab hydrolysates. To fine optimal protease enzyme, alcalase, bromelain, flavourzyme, neutrase, papain, and protamex were selected to evaluate the DPPH radical scavenging activity and finally bromelain to show the best activity was selected. The molecular weight of bromelain hydrolysates were distributed with range from 500 to 3,200 Da and 7 different molecules or more. The amino acids related to antioxidant capacity was about 42.54%. The processes optimization study used was the response surface methodology. The ranges of processes were the reaction temperature of 40 to $60^{\circ}C$, pH 6 to 8, and enzyme concentration 1 to 3%(w/v). As a result, the optimization of process was determined at temperature of $55^{\circ}C$, pH of 6.5, and enzyme concentration of 3%(w/v). In these conditions, degree of hydrolysates were maximum 71.60%. Therefore, we expect that those products are useful as functional food ingredients.