• Advances in environmental research
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• v.1 no.1
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• pp.15-35
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• 2012

Mercury (Hg) is a global environmental pollutant that has been the cause of many public concerns. One particular concern about Hg in aquatic systems is its trophic transfer and biomagnification in food chains. For example, the Hg concentration increases with the increase of food chain level. Fish at the top of food chain can accumulate high concentrations of Hg (especially the toxic form, methylmercury, MeHg), which is then transferred to humans through seafood consumption. Various biological and physiochemical conditions can significantly affect the bioaccumulation of Hg-including both its inorganic (Hg(II)) and organic (MeHg) forms-in fish. There have been numerous measurements of Hg concentrations in marine and freshwater fish worldwide. Many of these studies have attempted to identify the processes leading to variations of Hg concentrations in fish species from different habitats. The development of a biokinetic model over the past decade has helped improve our understanding of the mechanisms underlying the bioaccumulation processes of Hg in aquatic animals. In this review, I will discuss how the biokinetic modeling approach can be used to reveal the interesting biodynamics of Hg in fish, such as the trophic transfer and exposure route of Hg(II) and MeHg, as well as growth enrichment (the increases in Hg concentration with fish size) and biomass dilution (the decreases in Hg concentration with increasing phytoplankton biomass). I will also discuss the relevance of studying the subcellular fates of Hg to predict the Hg bioaccessibility and detoxification in fish. Future challenges will be to understand the inter- and intra-species differences in Hg accumulation and the management/mitigation of Hg pollution in both marine and freshwater fish based on our knowledge of Hg biodynamics.

• Korean Journal of Ichthyology
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• v.18 no.2
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• pp.119-128
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• 2006

Fish assemblages associated with eelgrass beds and unvegetated area were compared based on specimens collected every month in Jindong Bay. The common fish species were Hexagrammos otakii, Acanthopagrus schlegeli, Lateolabrax japonicus, Pholis nebulosa, P. fangi, Leiognathus nuchalis, Repomucenus valenciennei, and Acanthogobius flavimanus. H. otakii, A. schlegeli, P. nebulosa and L. japonicus were higher abundance in an eelgrass bed than unvegetated area, whereas P. fangi, R. valenciennei and A. flavimanus were higher in unvegetated area. Sillago japonicus, Hippocampus japonica, Takifugu niphobles, Pseudoblennius percoides, Sebastes inermis, Syngnathus schlegeli, Sebastes schlegeli were found in an eelgrass bed, but not in unvegetated area. Most of fish species were primarily small fish species or juveniles of fish species in an eelgrass bed, while larger fish species were found in unvegetated area. The eelgrass bed in Jindong Bay seem to play a nursery role for fishes. Seasonal variations in both species composition and abundance were large in two habitats; higher number of species and individuals occurred May 2002, and April 2002 to July 2002, while biomass was the highest in April 2002 and July 2002. Fish numbers as well as biomass were lowest in January 2002. Species richness, number of individuals and biomass of fishes in an eelgrass bed were significantly higher than those of in unvegetated area. These result suggest that differences in fish species richness and abundances are primarily related to habitat structure. Different habitat preferences were evidenced for the juveniles and adult of several fish species.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.57 no.4
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• pp.467-478
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• 2024

The fish assemblage characteristics in the coastal waters of Sinchang-ri in the Western region of Jeju Island were determined using trammel net samples collected from 2012 to 2022. During the survey period, 81 fish species (43 families, 12 orders) were identified. Tetraodontiformes (4 families, 9 species) and Perciformes (26 families, 57 species) accounted for 84% of the total number. Annual species variation was highest in 2017 and 2019 (36 species) and lowest in 2015 (26 species). Seasonal species variation was higher in summer (peak, 58 species) than winter (peak, 41 species). The number of individuals (1,509) and biomass (446.5 kg) peaked in August (summer) and were lowest in February (winter; 415 individuals, and 150.7 kg). 41 (50.6%) subtropical fish species were identified, and the number of species was highest in 2020 {21 (61.8%) and lowest in 2014, 2017 [16-18 (47.1-47.4%)]}. Subtropical fish species, individuals and biomass were significantly correlated with environmental factors (summer temperatures) at the sampling sites. Scarbreast tuskfish Choerodon azurio, balloon fish Diodon holocanthus, flag fish Goniistius zonatus, bluestriped angelfish Chaetodontoplus septentrionalis, hairy stingfish Scorpaenopsis cirrhosa, threeline grunt Parapristipoma trilineatum, and blackfin sweeper Pempheris japonica were the dominant species of subtropical fish in the study sites.

• Korean Journal of Ichthyology
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• v.26 no.3
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• pp.212-221
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• 2014

Species composition and bimonthly changes of fish community were investigated with the fishes collected by using both trammel nets and fish pots in the coastal waters of Sagyeoi, Jeju Island from May 2009 to February 2010. A total of 1,921 individuals (324,206 g in biomass), which comprise 10 orders and 35 families with 60 species, were collected during the study period. Among 60 species, 52 species were caught by trammel nets, 20 species by fish pots, and 12 species by both fishing gears. The five dominant species were Pseudolabrus sieboldi, Plotosus lineatus, Pteragogus flagellifer, Sebastiscus marmorattus and Diodon holocanthus in the aspect of total number of individuals, and Diodon holocanthus, Sebastiscus marmorattus, Stephanolepis cirrhifer, Pseudolabrus sieboldi, Parupeneus chrysopleuron in biomass. Each characteristics of fish community such as the number of species, the total number of individuals, and biomass were highly correlated with water temperature and salinity, which were all statistically significant at the 5% significant level. In other words, there was a tendency of increment of each characteristics according to a raise in water temperature or a decrease of salinity, and vise versa. The number of species, the total number of individuals, and biomass of fishes were highest in August and lowest in February.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.34 no.3
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• pp.309-319
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• 1998

Species composition and seasonal variations of fishes collected by winged stow net on anchors in the coastal water off Namhae Island was studied from May 1989 m April 1990. During the study period, a total of 56 fish species were collected. Engraulis japonicus, Conger myriaster, Trichiurus lepturus, Sardinella zunasi, Ammodytes personatus, and Thryssa kammalensis predominated. These six species accounted for 93.9% of the total number and 81.3% of the total biomass of fishes collected. Fishes collected by winged stow nets on anchors were primarily small fish species or early juveniles of large fish species. Both abundance and species composition of fishes changed with season. Seasonal peaks of number of species occurred in spring and fall, while those of number of individuals and biomass occurred in spring. The lowest number of individuals and biomass were observed in winter. Low species diversity indices were observed in summer. These low diversity indices in summer were mainly due to predominance of E. japonicus which accounted for approximately 90% of all fishes collected. More species and greater biomass were collected during nighttime.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.22 no.1
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• pp.1-8
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• 1989

Demersal fish community in Cheonsu Bay was analyzed using fish samples collected by a small otter trawl from March to November, 1986. Of the 32 species identified, Nibea argentatus, Chaturichthys stigmatias Crptocentrus filifer, Cynoglossus joyneri and Jonius belengeri pre-dominated in abundance. Based upon principal component analysis of species composition data, the fishes were grouped into resident, migrant and temporal species. Resident fish wintered in the deeper part of the bay, showing a peak in biomass during cold months. In spring, warm weather seasonals, adult N. argentatus and J. belengeri, migrated o the bay for spawing. However, the biomass of the migrant was not more than that of the wintered adult residents. From July to September, juveniles of many species were collected, but the number of individuals was smaller than that of the littoral or pelagic zones. This suggests that the deeper area of the bay did not serve as a main nursery ground of the juveniles with the exception of two migrant scianid fishes. As a result, the benthic fish of the bay were more abundant in cold months than in summer.

• Korean Journal of Environment and Ecology
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• v.38 no.3
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• pp.263-276
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• 2024

Fish community characteristics and the influence of sampling gear were investigated in Lake Singal, South Korea, from August 2020 to October 2021. The employed sampling gears included a kick net, cast net, gill net, and fyke net, which are commonly utilized within the lake. Across three survey stations, a total of 18 fish species from seven families, comprising 3,501 individuals and contributing to a total biomass of 117,670 grams, were identified. Dominance among species was assessed based on individual count and biomass. Pseudorasbora parva was the most abundant, constituting 29.9% of the total catch, followed by Zacco platypus (25.1%) and Micropterus salmoides (19.3%). In terms of biomass, Carassius auratus was predominant, accounting for 45.1%, followed by Cyprinus carpio (17.4%) and M. salmoides (14.3%). Among the sampled species, three were identified as endemic to Korea: Squalidus japonicus coreanus, Cobitis nalbanti, and Odontobutis interrupta. Additionally, four exotic species were recorded, including M. salmoides and Lepomis macrochirus, both classified as invasive alien species, along with C. cuvieri and a variant of Cyprinus carpio (nudus type). Analysis of the average standard length (SL) and body weight (BW) revealed significant size variations among species. P. parva, the dominant species, measured 60 ± 24.1 mm (SL) and weighed 4.4 ± 3.42 g (BW). The subdominant species, Z. platypus, exhibited an SL of 82 ± 17.6 mm and a BW of 10.4 ± 7.27 g. M. salmoides, another dominant species, registered 96 ± 25.1 mm (SL) and 24.9 ± 96.02 g (BW), while C. auratus measured 125 ± 77.3 mm (SL) and weighed 168 ± 336.5 g (BW). In terms of gear-specific performance, the kick net captured eight species from three families, totaling 302 individuals with a biomass of 1,269 g. The cast net was more effective in coastal zones, collecting 11 species from four families, amounting to 948 individuals and 31,343 g of biomass. The gill net yielded the highest biomass, capturing 13 species from four families with 682 individuals weighing 69,695 g. The fyke net recorded the highest species diversity and number of individuals, capturing 15 species from seven families, totaling 1,569 individuals and 15,362 g of biomass. The fyke net proved most efficient in species and individual counts, whereas the gill net was superior for biomass collection. Conversely, the kick net demonstrated effectiveness in collecting small benthic species in coastal areas.

• Korean Journal of Ichthyology
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• v.22 no.3
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• pp.186-194
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• 2010

Seasonal variation in species composition and abundance of fish assemblage in the coastal waters off Gori were determined using monthly samples collected by a three-side fyke net in 2006. Of a total of 59 fishes collected, the dominant species were Trachurus japonicus, Mugil cephaIus, Konosirus punctatus, Apogon lineatus, Chelidonichthys spinosus, Ditrema temmincki, Sebastes schlegeli and Apogon semilineatus. These 8 fishes accounted for 92.7% of the total number of individuals collected. The number of fish species, number of individuals, biomass and species diversity indices fluctuated with the seasons. The peak number of fishes occurred in December, whereas biomass of fishes was the highest in March. The number and biomass of fishes were lower in January corresponded with the low temperatures, and the diversity indices were lower in December than in any other month.

• 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.

• Korean Journal of Ichthyology
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• v.27 no.4
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• pp.310-316
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• 2015

The seasonal and interannual variation in the species composition and abundance of the fish assemblage were studied. Fish samples were collected seasonally over 4 year (2005 to 2008) using pots in the southern coast of East Sea. During the study period, a total of 32 fish species belonging to 24 families were collected. The dominant species were Conger myriaster, Paracentropogon rubripinnis, Liparis tanakae, Parapercis sexfasciata, Eptatretus burgeri and Clupea pallasii pallasii, which accounted for 91.9% of the total number of individuals collected. The number of species, number of individuals, biomass, and diversity fluctuated with season. The peak number of species and number of individuals occurred were in August 2008, whereas the biomass was the highest in August 2005 and diversity was in May 2008. The abundance of dominant species also showed some seasonal and interannual changes. A one-way analysis of similarity (ANOSIM) showed that the fish assemblage in 2008 was significantly different from those of 2005, 2006 and 2007, whereas there was no significant difference among seasons over 4 years.