• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.4
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• pp.232-238
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• 2005

This paper describes reproduction, population structure, growth and size at sexual maturity of a deep-water mud shrimp (Solenocera melantho) in the adjacent waters of Geomun Island, Korea. The shrimp was caught by a beam trawl from November 1998 to December 1999. Spawning period was estimated by gonadosomatic index to be from August to early November with a peak in October to early November. Female shrimps were $12\%$ matured at 16 mm in carapace length, $33\%$ matured at 18 mm and $75\%$ matured at 22 mm. The size at $50\%$ maturity for female was estimated to be 20.65 mm in carapace length. Breeding season was estimated to be from August to early November with a peak in October to early November. The size at $50\%$ inseminated was 19.81 mm CL. The fecundity was 87,500-405,200 and related exponentially to carapace length and total weight. This species survived between 25 and 26 months. The maximum carapace length of females and males were 48 mm and 34 mm respectively. Sex ratio was $51.3\%$, and the females were preponderant. Growth was estimated by modified von Bertalanffy growth function incorporating seasonal variation in growth in both years females (K=1.019/yr and $L_{\infty}$=51.731 mm CL) grew faster, reaching a larger size at a given age than males (K=1.848/yr, and $L_{\infty}$=27.499 mm CL). This is indicated by differences in growth performance indices $(\varphi')$ between females (3.291) and males (3.145).

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.49 no.3
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• pp.270-281
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• 2013

Hydro-acoustic surveys with scientific echo sounder were carried out to estimate the total density and distribution of the juvenile cod in Jinhae bay, Korea. The surveys were conducted 4 times from May to June using 2 frequency method (38kHz and 120kHz) and beam trawl were used to investigate the species composition. Also the catch amounts of juvenile cod were compared with the cod density estimated by the hydro-acoustic method. It was confirmed that the juvenile cod was stayed in Jinhae bay in early June and There was the relationship between catch of juvenile cod and the estimated density by hydro-acoustic survey. The number of juvenile cod was consequently about 365,000 fish (CV 12.9%) in May and 113,000 fish (CV 9.2%) in May based on the hydro-acoustic data.

• 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.40 no.1
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• pp.86-94
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• 2004

This study was conducted to mesh selectivity of Beam trawl for shrimps fishing experiment in the coastal waters around Geomundo, South sea of Korea, during from Oct. to Nov. 2002. The selectivity parameters of big head shrimp (Solenocera melantho) have been studied on the covered con-end method. with mesh of 8, 38, 51 and 61 mm. Selection curves and selection parameters were calculated by using a logistic function S=1/(1+exp-(aCL+b)). The mesh selection master curves were estimated by S=1/(1+exp$^{({\alpha}(CL/M)+{\beta}}$), and the optimum mesh size were calculated with (L/M)50 of master curve. Optimum mesh size and selectivity master curves for the southern rough shrimp (Yrachysalambria curvirostris) and smoothshell shrimp (Parapenaeopsis tenella) optimum mesh size and selectivity master curves were estimated by big head shrimp master curves. The results obtained are summarized as follows : Selection parameters '${\alpha}$' and '${\beta}$' of the master curve for big head shrimp were 8.84 and -5.89, and The selection factor of the master curve (L/M)$_{50}$ was 0.67. The optimum mesh size of minimum length for sexual maturity for big head shrimp was 30.7 mm. Estimated (L/M)$_{50}$ for southern rough shrimp and smoothshell shrimp by using the master curve of big head shrimp was 0.73 and the optimum mesh sizes were 25.5 mm for southern rough shrimp and 16.9 mm for smoothshell shrimp, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.5
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• pp.439-477
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• 2000

Seasonal variation in species composition of fishes in the eelgrass bed in Angel Bay of the southern coast of Korea was determined using monthly samples by a beam trawl from April 1998 to March 1999, A total of 39 species, 2,065 individuals and 8,930 g of fishes were collected during the study period. The fish were composed of the small-sized resident species and the juveniles of Leiognathus nuchalis, Pholis nebulosa, Spgnathus schlegeli and Sebastes ineinis predominated in abundance, accounting for $60{\%}$ of total number of individuals. The number of species and biomass were low from December to March when the water temperature was low, The biomass increased by the catch of a large number of L. nuchalis and S. inemis in April and May when the eelgrass grew fast. The fish numbers decreased in June and July when the adults of the resident species declined after the spawning. A large number of juveniles which had released in spring occurred in August. The biomass of fish decreased from September, and a few number of fish were collected in winter. Species were grouped into four by cluster analysis: the warm season group including P. nebulosa, S. schlegeli and L. nuchalis, the cold season group including Chaenogobius heptaoanthus and Platycephalus indieus, the group of fish species occurred during the growing season of eelgrass such as P. couoides, S. inermis and P. perooides, and the group of fish species occurred during decaying season of eelgrass such as S. cirrhifer and H. coronatus. Principal component analysis indicated that seasonal variation in species composition was determined by the water temperature and standing crops of eelgrass.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.3
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• pp.175-184
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• 2012

Changes of fish assemblage inhabiting around Dae Island in Gwangyang Bay, Korea were investigated using a small beam trawl monthly from March 2009 to February 2010. These data were compared with those obtained in previous studies(1990~1991 and 1995~1996) at our study sites. A total of 8,133 fish belonging to 74 species in 38 families were collected. Leiognathus nuchalis, Argyrosomus argentatus, Acentrogobius pellidebilis, Sillago japonica, Apogon lineatus, Thryssa hamiltoni, Repomucenus richardsonii, Pholis nebulosa, Pleuronichthys cornutus, Hexagrammos otakii, and Limanda yokohamae dominated, and these were responsible for 89.5% and 58.9% in the number of individuals and in biomass, respectively. These were primarily small species or early juveniles of larger species. Seasonal variation in both species composition and abundance was large: the peak number of fish species occurred in May and October 2009, whilst both number of individuals and biomass were the highest in May 2009. Fish numbers as well as biomass was lowest in January and February 2010. Seasonal changes in the abundance of fishes corresponded with temperature. Compared with the previous studies, the total number of individuals and biomass per unit area($m^2$) were higher, and the predominance of L. nuchalis occurred while abundances of Liparis tanakai were significant decreased. These results seemed to be change of species composition in fish assemblage which was due to variation of annual environmental characteristics in Gwangyang Bay.

• Korean Journal of Ichthyology
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• v.24 no.1
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• pp.11-19
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• 2012

Seasonal fish species composition in the sandy shore adjacent to eelgrass bed was determined. Monthly samples were collected by a beam trawl from August 2009 to July 2010. A total of 38 species, 1,232 individuals and 5,277.7g of fishes were collected. The dominant species were $Favonigobius$ $gymnauchen$, $Takifugu$ $niphobles$, $Hypodytes$ $rubripinnis$, and $Rudarius$ $ercodes$. These four dominant fish accounted for 73.2% of the total number of individuals, and 53.9% of the biomass of collected fish. During the survey, the water temperature ranged from 11 to $25^{\circ}C$, and the salinity ranged from 29 to 35 psu. The monthly species diversity index showed the lowest value of 0.89 in March and highest value of 2.35 in June 2010. Fish species composition and abundance in Myeongsa sandy shore, were similar to that the adjacent eelgrass bed, but were different from those of Gujora sandy shore open the sea.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.1
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• pp.9-16
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• 2013

The growth and production of Aulichthys japonicus (6.70~15.32 cm TL) were investigated in an eelgrass bed of Dongdae Bay, Korea throughout 2006. A total 888 A. japonicus were collected with a small beam trawl. Growth in fish total length was expressed by the von Bertalanffy's growth equation as: $L_t=24.8257(1-e^{-0.5583(t+0.4816)})$. The densities, biomass, daily, annual production, and P/B ratio were $0.01{\pm}0.009/m^{-2}$, $0.17{\pm}0.16g/m^2$, $0.00006{\pm}0.00006g$ AFDW/$m^2$/day, 0.02g AFDW/$m^2$/yr, and 0.12, respectively. Monthly variation in production of A. japonicus was large; the peak occurred at July, September and November 2006 (0.000182, 0.000127 and 0.000123 g AFDW/$m^2$/day), where as the lowest value was 0.000003g AFDW/$m^2$/day at April and May 2006. Monthly change in production of A. japonicus was positive correlated with number of individuals, biomass and growth rate.

• Korean Journal of Ichthyology
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• v.30 no.2
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• pp.107-113
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• 2018

To observe species composition and seasonal variation of fish in the coastal area, monthly underwater visual census were conducted from October 2016 to September 2017 in Tongyeong, Korea. A total of 5,358 individuals belong to 45 species were observed during the study. Perciforme fish were the most dominant (29 species), followed by Scorpaeniformes (8 species), Tetraodontiformes (3 species). The most dominant species is Sebastes inermis (19.2%), and followed by Rudarius ercodes (18.5%). Thirty three species with the highest abundance were observed in October 2016 and only 4 species were observed in February 2017. Among three subtropical fishes, such as Chaetodontoplus septentrionalis, Labroides dimidiatus, and Ostracion cubicus, the latter 2 species were firstly observed in the southern coast of Korea. Compared with the previous studies using conventional tools such as beam trawl and seine net for fish collection, underwater visual census is much more efficient way to investigate fish diversity and assemblages in coastal waters.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.5
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• pp.461-467
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• 2014

The growth and production of Pseudoblennius cottoides (1.80~10.01 cm TL) were investigated in an eelgrass bed of Dongdae Bay, Korea throughout 2006. A total 702 P. cottoides were collected with a small beam trawl. Growth in fish total length was expressed as: $TL=0.0539d^{0.9105}$. The relationships between total length body weight was estimated as $W=0.0079TL^3.1103$. The densities, biomass, daily, annual production, and P/B ratio were $0.06{\pm}0.062/m^2$, $0.10{\pm}0.144g/m^2$, $0.0005{\pm}0.0006g\;AFDW/m^2/day$, $0.1833g\;AFDW/m^2/year$, and 1.813, respectively. Monthly production of P. cottoides were greatly peak in May, July and September (0.0029, 0.0031 and $0.0019g\;AFDW/m^2/day$) when the biomass was high, and the lowest value in December (0.00004g AFDW/m^2/day) when the biomass was low. Monthly change in production of P. cottoides was positively correlated with biomass and temperature.