• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.60 no.2
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• pp.114-127
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• 2024

A variation of fish assemblage in the coastal waters of Sagye-ri, southern Jeju Island was determined using samples collected by trammel net from 2012 to 2022. The total fish species caught by trammel net were identified 88 species, 46 families, 12 orders, and the number of appearance and biomass were 3,479 individuals and 883.6 kg. The annual variation of species was the highest in 2013 at 46 species and the lowest in 2021 at 30 species. The seasonal variation of species was higher in summer at 67 species and lower in winter, autumn at 47 species. The annual diversity index, evenness index, and richness index were appeared 2.42-3.00, 0.69-0.78 and 5.18-7.24 at each years. The dominance index appeared highest in 2013 and the lowest in 2018. Cluster analysis based on the number of individuals of fish was classified into two groups at the dissimilarity level of 57%, and results of SIMPROF analysis revealed significant differences in community structure among the two groups. The subtropical fishes were identified a total of 42 species (47.7%) and the number of species was higher in 2013 at 25 (54.3%) species and lower in 2018 and 2021 at each 17 (54.8~56.7%) species. The dominant species of subtropical fishes were appeared rabbit fish (Siganus fuscescens), scarbreast tuskfish (Choerodon azurio), bluestriped angelfish (Chaetodontoplus septentrionalis), balloon fish (Diodon holocanthus), and flag fish (Goniistius zonatus) at study sites.

• Korean Journal of Ichthyology
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• v.18 no.3
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• pp.223-233
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• 2006

The annual and spatial changes in the species composition of catch off Yeosu were analyzed using the daily sales slip catch data by a set net in the inshore waters off Dolsan Islands in Yeosu from April to October 2001, off Yeon Islands of Yeosu from April to October 2002 and in the offshore waters off Dolsan Islands of Yeosu from April to December 2003, respectively. Scomberomorus niphonius, Seriola spp., Trichiurus lepturus, Engraulis japonicus, Sarda orientalis, Todarodes pacificus, Pampus echinogaster, Sardinella zunasi, Scomber japonicus, Lophius litulon and Loligo beka were dominant species in abundance, indicating that pelagic fish were mainly caught by a set net off Yeosu. S. zunasi, P. echinogaster, Platycephalus indicus and L. beka inhabited mainly in the inshore waters, and S. niphonius, Seriola spp., T. lepturus, P. echinogaster, T. pacificus, Takifugu porphyreus and Pagrus major resided mainly in the offshore waters as the pelagic resident species. E. japonicus was a representative dominant species moving between the inshore and the offshore waters seasonally. S. zunasi and E. japonicus occurred in the inshore waters, and E. japonicus, L. litulon and Seriola spp. begain to be caught in the deep offshore waters in spring. Total catch was high during the summer season by migration of the open sea species such as T. lepturus, S. niphonius, S. japonicus, Seriola spp., S. orientalis, P. echinogaster and T. pacificus. In fall, S. niphonius, E. japonicus, Sphyraena pinguis, Siganus fuscescens and Leiognathus nuchalis were dominant in the inshore waters, and S. niphonius, P. echinogaster, Hyporhamphus sajori, S. japonicus and T. lepturus continued to occur from summer in the offshore waters but total catch decreased, indicating the typical seasonal variation pattern of the temperate region. Most of catchable fishes by a set net were the pelagic species showing a significant temporal variation. Collection and analysis of daily catch data by large set nets can be used to determine seasonal variation in species composition of pelagic fish in a study area.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.2
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• pp.319-344
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• 2015

A seasonal characteristic of marine environment and fish assemblages in the coastal waters of Jeju Island were determined using samples collected by a trammel net in from 2012 to 2013. Annual mean temperature and salinity were $18.8^{\circ}C$, 33.7psu (2012) and $18.8^{\circ}C$, 33.8psu (2013) which shows stable water mass. nutrient concentrations represent that dissolved inorganic nitrogen (DIN) ranged from 0.030 to 0.217mg/L, dissolved inorganic phosphorus (DIP) from 0.002 to 0.010mg/L, and silicate ($SiO_2$) from 0.096 to 0.292mg/L. Chlorophyll a concentrations of phytoplankton ranged from 0.905 to $1.125{\mu}g/L$ were appeared the highest in summer and the lowest in winter. Suspended Solid(SS) concentrations ranged from 1.200 to 2.100mg/L (mean, 1.634mg/L) were appeared the highest in autumn and the lowest in spring. During the survey period, a total of 83 species (48 families and 12 orders) of fishes were identified, Perciformes and Scorpaeniformes accounted for 63.9% of the total number. The number of species was higher in summer than in winter, showing a peak in summer at 57 species and a low in winter at 47 species. The number of individuals and the biomass peaked in summer at 694 individuals and 151.9kg, and were the lowest in autumn at 466 individuals and 106.5kg. The diversity index, evenness index and richness index were appeared 2.92~3.14, 0.75~0.83 and 7.06~8.56 at each stations. the dominance index were appeared highest in spring and summer, were appeared the lowest in winter and autumn. The Filefish (Stephanolepis cirrhifer), Bluestriped angelfish (Chaetodontoplus septentrionalis), Marbled rockfish (Sebastiscus marmoratus), Rabbit fish (Siganus fuscescens), Blackfin sweeper (Pempheris japonica) were dominant species, which occurred abundantly during the entire survey period. The subtropical fishes were identified total of 41 species (49.4%) and the number of species was higher in summer at 29 (50.9%) species and a low in winter at 20 (42.6%) species. The dominant species of subtropical fishes were appeared Bluestriped angelfish, Blackfin sweeper, Rabbit fish, Scarbreast tuskfish (Choerodon azurio), Ballonfish (Diodon holocanthus), Flagfish (Goniistius zonatus), Blue-spotted boxfish (Ostracion immaculatus) in study sites. The subtropical fishes of species, individual and biomass showed significant correlation with environmental factors (Chlorophyll a, DIN, DIP, $SiO_2$) in almost all sampling sites.

• Korean Journal of Ichthyology
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• v.13 no.3
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• pp.210-219
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• 2001

The fisheries resources of the set net fishery on four fishing grounds (Pyuong Dae, Gu Eum, Du Moah, Gang Jeong) in coastal waters of Jeju Island were studied to the determine catch-variation characteristics from January, 1998 to December, 1999. A total catch of 153,862 kg was made through the survey period. The large total was related mainly to the high catch of Trachurus japonicus, which comprised 58.2% of the total. Other dominant species which account for 23.0% of the total catch were Siganus fuscescens, Todarodes pacificus, Loligo chinesis, Seriola lalandi, Sepioteuthis lessoniana, and Seriola quinqueradiata. Catch density was high in Gu Eum (more than 100,000 kg), whereas those in Pyuong Dae, Du Moah, and Gang Jeong were less than 30,000 kg in total. The fishing period of the set net fishery was from April to December, which was also closely related to the variation of the sea water temperature in the fishing grounds. The ranges of water temperature in the four fishing grounds were $18{\sim}26^{\circ}C$ in Pyuong Dae, $16{\sim}26^{\circ}C$ in Du Moah, $15{\sim}26^{\circ}C$ in Gu Eum, and $15{\sim}26^{\circ}C$ in Gang Jeong.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.3
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• pp.174-180
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• 2001

Dusky spinefoot, Siganus fuscescens live primarily in shore reefs with sea weeds, like around Jeju Island in Korean south sea. Therefore they are caught much by set net in the coast of Jeju Island. We carried out measurements of the dorsal aspect target strengths of Dusky spinefoot in order to study the influences of swim bladder for fishes. and have obtained some desired results though not sufficiently complete as comparison with target strengths of fishes before and after the air gas in the swim bladder of fish is taken off by an injector. The appropriate equations share the common form TS = A + 20 log L. TS = B + 20/3 log W where TS is the average dorsal aspect target strength in decibels. L is the fish total length in centimeters. W is the fish total weight in grams, and the coefficient A and B are determined by a least mean squares regression analysis. The results obtained before the air gas in the swim bladder of fish is taken off are TS = -63.16 + 20 log L TS = -50.50 + 20/3 low W and, the results obtained after the air gas in the swim bladder of fish is taken off are TS = -65.29 + 20 log L TS = -52.62 + 20/3 log W As above result, the differences of target strengths before and after the air gas is taken off from swim bladder are 2.12-2.13 dB, but the maximum difference of target strengths of both cases averaged according to the fish aspects from $-45^\circ$ to $45^\circ$ is 5.87 dB, and the average difference of them is 2.01 dB.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.3
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• pp.223-231
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• 2001

For the purpose of providing the basic data on the improved fishing gear and the man power saving, which contribute to enhance fishing efficiency of set net in the coast of Jeju Island, this study executed the test of fish tank by reducing these actual nets by 1/30 and using the manufactured model nets, and observed and interpreted the behaviors of entering and escaping of the schools of mackerel Scomber japonicus, horse mackerel Trachurus japonicus and rabbit fish Siganus fuscescens. Thereby the result is as follows ; 1. After the elapsed time of 60 seconds, in case of rectangular set net, the ratio for entering by a school of fish marked 50% with mackerel, 18% with horse mackerel and 28% with rabbit fish, and in case of pound net, the ratio for entering net by a school of fish marked 70% with mackerel, 60% with horse mackerel and 30% with rabbit fish. 2. After the elapsed time of 60 seconds, in case of rectangular set net, the ratio for escaping by a school of fish marked 70% with mackerel, 40% with horse mackerel and 24% with rabbit fish, and in case of pound net, the ratio for escaping from net by a school of fish marked 0% with mackerel, 0% with horse mackerel and 3% with rabbit fish. 3. After the elapsed time of 60 seconds, in case of rectangular set net, the ratio for remaining by a school of fish marked 30% with mackerel, 60% with horse mackerel and 76% with rabbit fish, and in case of pound net, the ratio for remaining by a school of fish marked 100% with mackerel, 100% with horse mackerel and 97% with rabbit fish.

• Korean Journal of Ichthyology
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• v.30 no.1
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• pp.55-64
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• 2018

Fish assemblages in a sandy shore and an eelgrass bed were compared based on monthly samples in the southern coastal water of Korea. Samples were collected by a beam trawl in the sandy shore and a surf net in the eelgrass from March to February 2012. The common fish species were Syngnathus schlegeli, Pseudoblennius cottoides, Pholis nebulosa, Favonigobius gymnauchen, Gymnogobius heptacanthus, Pseudopleuronectes yokohamae, Takifugu niphobles. Among them S. schlegeli, Urocampus nanus, P. cottoides, P. nebulosa, T. niphobles were high abundance in the eelgrass bed than in the sandy shore, whereas Acanthogobius flavimanus, Acentrogobius pflaumi, F. gymnauchen, G. heptacanthus, P. yokohamae were high in the sandy shore. Aulichthys japonicus, Hippocampus coronatus, Sebastes inermis, Lateolabrax japonicus, Siganus fuscescens were found in the eelgrass bed, and Thryssa hamiltoni, Mugil cephalus, Inimicus japonicus, Platycephalus indicus, Hexagrammos otakii, Furcina ishikawae, Liparis tanakae, Repomucenus curvicornis, and Eutaeniichthys gilli were observed in the sandy shore. Species composition and abundance varied seasonally in two habitats; The number of species and abundance was high in August and September, while biomass was the highest in April and September. Fish numbers as well as biomass were lowest in February. Number of individuals and biomass of fish in the eelgrass bed were significantly higher than those of in the sandy shore. Some fish preferred to live in the eelgrass were collected in the sandy shore, while fish preferred to live in the sandy shore were rarely collected in the eelgrass.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.2
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• pp.133-139
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• 2001

In order to obtain fundamental data for estimation of fisheries resource by echo sounder, we carried out the measuring of dorsal aspect Target strengths for rock bream and dusky spinefoot fishes that were caught much around the Jeju Island and in South Sea of Korea. The appropriate equations share the common form. TS=A+20 log L, where TS is the average dorsal aspect target strength in decibels, L is the fish total length in centimeters, and the coefficient A is determined by a least mean squares regression analysis. For rock bream, the result is TS=-72.97+20 log L and, for dusky spinefoot it is TS=-63.16+20 log L And, we have investigated the bearing range of maximum dorsal aspect target strength for all of rock bream and dusky spinefoot by the echo sounder with transducer of which frequency is 200kHz. They are $-12^\circ$-$-21^\circ$and $-1^\circ$--8 espectively, when the fishes is swimming down to the bottom. The maximum dorsal target strengths are -41.50dB at -18 or rock bream and -30.69dB at $-6^\circ$for dusky spinefoot.

• Korean Journal of Ichthyology
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• v.20 no.1
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• pp.28-35
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• 2008

Fishes by a set net in the coastal waters off Gwideuk, Jeju Island were studied to determine species composition and catch variation, 2004. The fishing period conducted by a set net in Gwideuk fishing ground were from April to December. A total of 45,473.2 kg including 21 species was caught during the survey period. Most of them consisted of fishes of 17 species and a few were cephalopods of 4 species. Dominant species were Trachurus japonicus and Siganus fuscescens, 44.3% in the total. And sub-dominant species were Sepioteuthis lessoniana, Seriola dumerili, Seriola quinqueradiata, Loligo bleekeri, Seriola lalandi accounting for 54.4%. Although the number of species had a tendency to decreased from July to December, the catch by a set net was higher in summer and autumn than in spring. Such catch variations were closely related to recruitment of dominant species and also the seasonal variation of fishing ground temperature.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.57 no.1
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• pp.10-24
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• 2021

A seasonal characteristic of fish assemblages in the coastal waters of Gapa-do was determined using samples collected by a trammel net from 2015 to 2019. Annual mean temperature and salinity were 18.9℃, 33.6 psu (2015), 19.5℃, 33.6 psu (2016), 18.9℃, 33.8 psu (2017), 18.8℃, 34.5 psu (2018) and 19.5℃, 33.7 psu (2019), which show a stable water mass. During the survey period, a total of 50 species (30 families and 8 orders) of fishes were identified, including Scorpaeniformes (3 families and 9 species) and Perciformes (18 families and 29 species) that accounted for 68% of the total number. The number of species was higher in summer than in winter, showing the peak in the summer by 35 species and the low in the winter by 20 species. The number of individuals and the biomass peaked in the summer by 690 individuals and 151.4 kg, and were the lowest in the autumn by 336 individuals and 76.6 kg. The annual diversity index, evenness index and richness index were appeared to be 2.54-2.75, 0.68-0.76 and 5.32-6.65 at each stations. The dominance index was appeared to be the highest in 2018 and the lowest in 2015. Marbled rockfish (Sebastiscus marmoratus), rock fish (Sebastes inermis), filefish (Stephanolepis cirrhifer), rabbit fish (Siganus fuscescens), porcupine fish (Diodon holocanthus) and smallscale blackfish (Girella melanichthys) were dominant species, which occurred abundantly during the entire survey period. Subtropical fishes were identified as a total of 24 species (48.0%) and the number of species was higher in 2019 by 20 (60.6%) species and lower in 2015 by 13 (44.8%) species. The dominant species of the subtropical fishes were appeared to be rabbit fish, porcupine fish, smallscale blackfish, flag fish (Goniistius zonatus), stripey (Microcanthus strigatus), grunter (Parapristipoma trilineatum), and bluestriped angelfish (Chaetodontoplus septentrionalis) at the study sites.