• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.1
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• pp.15-23
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• 1984

Difference of the entering and the escaping behaviour of shrimp(Palaemon pacificus) to the model traps were observed in accordance with netting materials, baits, type of traps and slope of flapper, and gathering responses were also investigated on the odour of bait extracts in the aquarium as the preliminary test. In order to investigate the difference in catch according to type and structure of traps those designated from A to E were made of iron frames and nettings. The type A was a conical shape with two entrances at its both sides and the others were square piller shape with one entrance at their upper surface(type B) or two entrance at their both ends(type C, D and E). However th type D and E were connected with flapper and the thye E was made by attaching iron frames of same height under the type D. The traps were prepared 10 each and so a total of 50 traps were used in the experiment at sea. The main species caught was Charybdis japonica, but Astroconger myriaster was also caught fairly. The catches of these species were significant in difference between the types of traps. That is, Charybdis japonica was caught more in type A, C and D than others and less in type B and E, and Astroconger myriaster was caught more in type A and D and less in type B and E. However the catch of Astroconger myriaster in type C, even if less than that in type A showed no significant difference with the other traps. The total catch of Charybdis japonica and Astroconger myriaster was almost same in order with the catch of Charybdis japonica. The type B and E seemed to be difficult in entering of fishes into them. However, the type A and C seemed to be easy not only in entering, but also in escaping. Especially, the type C showed more escaping. On the other hand, the type D seemed to be not so easy in entering of fishes as type A and C, but very difficult in escaping. Consequently, the escaping of fishes from the traps seemed to be more difficult in conical traps than any other traps. The catches might be influenced by the bait with bag compare to without bag and also the immersed time of traps into water for fishing.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.1
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• pp.69-77
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• 2010

We examined shrimp and bycatch species composition in the shrimp beam trawl fishery off Wan-do, Korea(in the major or fishing ground)from December 2004 to November 2005. We observed a total of 103, 072 individuals in 96 taxa. By densities of individuals, 96.97% were shrimps, 1.20% decapods, 1.10% fish, 0.30% cephalopods and 0.43% other species. By catch weight, 57.29% were shrimps, 26.33% fish, 6.82% decapods, 4.64% cephalopods and 4.92% other species. In spring, the dominant bycatch species by biomass were Okamejei kenojei, Lophiomus setigerus, and Charybdis bimaculata. In summer, the dominant species were Charybdis bimaculata, Muraenesox cinereus, and Paralichlhys olivaceus. In autumn, dominants were Okamejei kenojei, Conger myriasler, and Sefipinna tenuifilis, and in winter they were Okamjei kenojei, Chaeturichthys stigmatias, and Sillago japonica. Bycatch species composition and individual species abundances differed significantly among seasons, probably indicating that variations were related to the life history characteristics of bycatch species. The diversity index was highest in October (2.797) and lowest in July (1.012). The July dominance index (0.569) was much higher than in other months; evenness was highest in September (0.856) and lowest in July (0.374). During the study period, the bycatch-to-shrimp ratio of this fishery varied from 0.063 in February 2005 to 11.031 in May 2005, with a mean of 3.363 These temporal variations may be linked 10 variations in reproductive behaviors and migration patterns of the marine animals sampled.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.3
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• pp.264-273
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• 2014

To investigate species composition and seasonal variation of demersal organisms in the coastal waters off the Taean peninsula, otter trawl surveys were conducted from April 2010 to January 2011. A total of 75 species were collected, including 44 species of Pisces, 19 species of Crustacea, 6 species of Cephalopoda, 4 species of Gastropoda, and 1 species each of Bivalvia and Echinoidea. The dominant species in each season were Palaemon gravieri in spring, Charybdis bimaculata in summer, Loligo japonica in autumn, and Crangon hakodatei in winter. The number of species, individuals and biomass were highest in autumn and lowest in winter. The diversity index was highest in summer and lowest in winter. The dominance index was highest in winter and lowest in summer. The richness index was highest in autumn and lowest in winter. The evenness index was highest in summer and lowest in autumn. A cluster analysis showed that demersal organisms were divided into two groups; spring and winter organisms (Group 1) and summer and autumn organisms (Group 2). We detected a significant difference (P<0.05) between these groups, mainly owing to Platycephalus indicus, Repomucenus koreanus, and Paralichthys olivaceus within Pisces: Trachysalambria curvirostris, Metapenaeopsis dalei, P. gravieri, and C. hakodatei within Crustacea: and L. japonica within Cephalopoda.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.34 no.2
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• pp.185-190
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• 1998

The aim of this study was to develop the artificial trap baits being able to replace the natural anchovy or sardine baits. The fishing trials for evaluating the fishing efficiencies of the artificial baits were conducted with commercial traps at coastal areas near Tongyoung, southern Korea. The preferable artificial baits which were made of minced anchovy, sardine, mackerel, or fish surplus products mixed with wheat flour into dry or wet pelleted or crumbled types, were showed some merits as the following. \circled1 Fishing efficiencies of the artificial baits were same or little higher level than that of the natural bait anchovy; \circled2 bait cost were same or little lower level; \circled3 dry artificial baits stocked in the room condition showed good fishing efficiencies; \circled4 making of artificial baits were very simple; \circled5 there were no harm to the fish and little pollution to the environment; \circled6 the releasing rate of attractants in the artificial or natural bait showed similar patterns. The artificial baits using the fish by-products which were vacuum freeze-drying extract of boiled anchovy or tunas extract, showed lower catches in the conger eel, Coner miriaster, but similar catches in the crabs, mainly Charybdis japonica, to the those of natural anchovy bait.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.5
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• pp.521-531
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• 2010

This study examined the community structure and temporal variation of the macro-crustaceans on Jangbong tidal flat, Incheon, Korea. Macro-crustaceans on this tidal flat were collected using a modified otter trawl from November 1999 to January 2001. The macro-crustaceans comprised 32 species, 7,741 individuals, and 29,211.3 gWWt during the study period. The Jangbong tidal flat was dominated numerically by three shrimp (Palaemon carinicauda, Crangon affinis, and Metapenaeus joyneri) and two portunid crabs (Charybdis japonica and Portunus trituberculatus). The macro-crustacean assemblages were divided into two different season and species groups based on the q-mode and r-mode clustering methods. In terms of q-mode, they consisted of a winter species group from December through April and a summer species group from May through November. The r-mode analysis showed that the species group visiting the tidal flat in winter was dominated numerically by palaemonid and crangonid shrimps, while a species group characterized by an abundance of portunid crabs and penaeid shrimps was more frequent in spring, summer, and autumn. In conclusion, our study revealed distinct temporal variation in the tidal flat use by macro-crustaceans around Jangbong Island, Incheon, Korea.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.49 no.2
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• pp.106-115
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• 2013

A series of fishing experiments were carried out in the western coastal waters of Korea from May, 2006 to September, 2007, using gill nets of different mesh sizes (m=101, 121.8, 152.5, 176.8, and 191 mm) to determine the mesh selectivity of gill net for swimming crab, Potunus trituberculatus. The catch species was composed of swimming crab (87%), Thomas's rapa whelk Rapana venosa (5%), arthritic neptune Neptunea cumingi (2%), Japanese swimming crab Charybdis japonica (2%), marbled sole Pleuronectes yokohamae (1%), pen shell Atrina pectinata, ocellate spot skate Okamejei kenojei, and so on. The carapace length (CL) of each swimming crab caught in the experimental nets was measured. Sponge crab (egg-bearing female crab) was appeared from the end of June to August in the coastal waters. The master selection curve was estimated by applying the extended Kitahara's method. The selection curve showed that the gill nets of larger mesh size allowed more crabs of small carapace size to escape. The optimum value (CL/m) was 0.645 and the CL/m was estimated to be 0.301, 0.354, 0.391, 0.422, and 0.450 when the retention probabilities were 0.1, 0.2, 0.3, 0.4 and 0.5, respectively.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.33 no.2
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• pp.90-96
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• 1997

Until now the research was usually related in the fishing basket for crab charybdis japonica, concentrated one's effort to modification on the construction, shape, number of entrance of fishing basket etc.. But there's not make good used to the basically habit, shelter behavior of crab. etc., and was not fundamentally modified to the ability attracting the crab on net fishing basket. In this paper, first of all investigated to the behavior of crab in water tank and then two types modification fishing baskets could the increasing to ability attracting of crab on fishing basket were designed from the result obtained in this experiment and compared with modificated net fishing basket by Kim.Go(1987.1990) at a field and tank experiment. The results obtained are summarized as follows : 1. Being the fishing baskets had dropped in the tank bottom, the touched rate and reacted rate of crab according the elapsed time agree with to experiment of Kim.Go(1987.1990)in the mainly. however, in case of plate type tangle net, the touched rate of crab increased for a short time and then decreased and the reacted rate increased in a hurry to show a maximum and then was established. 2. The beginning catch time of crab was shortest in the plate type tangle net than the any fishing baskets because it's immediately entangled if the crab was touched only a part of body on net and latest in the net fishing basket. 3. A distance of between the touched rate and the reacted rate curve were the most short, wide in the plate type tangle net. therefore, the ability attracting of crab was excellent than the any fishing baskets and in case of pipe type fishing baskets, between the 150mm and 250mm seemed not difference and showed a tendency to increasing against the net fishing baskets. 4. Pipe type fishing baskets seemed to become a good shelting place for the crab because it showed a tendency to stagnate at the inside in that. 5. The mean catch per pot of crab among the net fishing basket, pipe type fishing baskets, plate type tangle net were highest in the pipe type fishing baskets than the net fishing basket and lowest plate type tangle net. Therefore it showed to difference against the tank experiment.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.1
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• pp.85-90
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• 1993

In this survey the results showing the highest values among the analyzed data of all specimens are summarized as follow. At Kwangyang bay Cu in the fishery was detected up to 1.208ppm and the level of Cu and Pb in sediment of this area were 2.13 and 4.34ppm, respectively. The contents of Hg in fishery and sediment of Yeosu bay were 0.102 and 0.032ppm. The levels of Pb in fishery and seawater of Sunchon bay were 0.039ppm and 0.013$\mu\textrm{g}$/L, respectively. At Posung bay the contents of Cd were 0.277ppm, 0.09$\mu\textrm{g}$/L and 0.08ppm in the specimens of fishery, seawater and sediment, respectively. The analyzed data of all specimens at Keamundo were very low level or undetectable. Of the 6 fishery samples, Charybdis japonica showed the upper level of Hg, Cu, Zn, Mn as 0.092, 1.905, 6.64, and 46.34ppm, respectively. The contents of Pb and Cd in Batillus cornatus were 0.045 and 0.38ppm respectively and other fishery had low level of heavy metal. In this study the contents of heavy metals analyzed in all specimens showed nearly natural occurrence level which is under the legal limits.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.4
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• pp.262-272
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• 2007

Diurnal and tidal variation in the abundance of the macro- and megabenthic assemblages were studied in the macrotidal flat, Incheon, Korea. The samples were collected by modified otter trawl during 8-9, June 2000. The macro- and megabenthic assemblages comprised a total of 60 species, including 6,309 individuals and 67,835.5 gWWt. As a result, the abundance pattern showed two different categories relating to diel and tidal cycles. First, the diel pattern of these assemblages was subdivided into 3 groups. 1) Diurnal species such as Hexagrammos otakii, Thryssa baelama, Loligo beka, Metapenaeus joyneri. 2) Nocturnal species such as Cynoglossus joyneri, Sebastes schlegeli, Charybdis japonica, Crangon affinis, Trachysalambria curvirostris, Metapenaeopsis dalei. 3)Other species showing no obvious pattern with Johnius grypotus, Platycephalus indicus, Repomucenus richardsonii. However, based on the result of Mann-Whitney U-test, diel patterns of macro- and megabenthos did not reveal any significant differences. Second, tidal variation in the macro- and megabenthic assemblages was significant between ebb and flood tides. Total macro- and megafaunal species number, abundance and biomass were higher in ebb tide$(13^h30',\;16^h30',\;1^h30',\;4^h30')$ than in flood tide$(19^h30',\;21^h30',\;10^h30',\;13^h00')$. As a consequence, the macro- and megabenthic assemblages were clearly influenced by tides but their diel variations were not significantly different.