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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Korean Journal of Fisheries and Aquatic Sciences
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Journal DOI :
The Korean Society of Fisheries and Aquatic Science
Editor in Chief :
Volume & Issues
Volume 46, Issue 6 - Dec 2013
Volume 46, Issue 5 - Oct 2013
Volume 46, Issue 4 - Aug 2013
Volume 46, Issue 3 - Jun 2013
Volume 46, Issue 2 - Apr 2013
Volume 46, Issue 1 - Feb 2013
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Seasonal Variation in the Dietary Fiber, Amino Acid and Fatty Acid Contents of Porphyra yezoensis
Shin, Dong-Min ; An, Se-Ra ; In, Seo-Kyoung ; Koo, Jae-Geun ;
Korean Journal of Fisheries and Aquatic Sciences, volume 46, issue 4, 2013, Pages 337~342
DOI : 10.5657/KFAS.2013.0337
Porphyra yezoensis is potentially an excellent source of dietary fiber, amino acids, and eicosapentaenoic acid (EPA) because this red seaweed is available in large quantities and is rich in polysaccharides, proteins, and n-3 fatty acids. This study determined the insoluble dietary fiber (IDF), soluble dietary fiber (SDF), neutral detergent fiber (NDF), acid detergent fiber (ADF), amino acid, and fatty acid contents of P. yezoensis harvested monthly from November 2011 to March 2012. The total dietary fiber (TDF) and IDF contents ranged from 27.2-34.9% and 18.5-26.9%, respectively, and were greater in March than November. The SDF content ranged from 4.9-8.4% and did not differ significantly during growth. Galactose and 3,6-anhydro galactose were the major sugars in IDF and SDF. The higher levels of galactose and 3,6-anhydro galactose in IDF might be due to associated porphyran-type polysaccharides. Mannose and xylose were also major sugars in IDF. The total amino acid contents decreased gradually from November to March. The total amino acid composition of Porphyra was dominated by alanine, glutamic acid, arginine, and aspartic acid. No significant changes in the fatty acid profile were observed throughout the study period. The dominant fatty acid during all seasons was EPA, which comprised as much as 50% of the total fatty acid content.
Food Quality Characteristics of Instant Gruel Prepared with Peeled Krill Euphausia superba Meat
Jung, Hae-Rim ; Choi, Eun-Hye ; Lee, Yang-Bong ; Chun, Byung-Soo ; Kim, Seon-Bong ;
Korean Journal of Fisheries and Aquatic Sciences, volume 46, issue 4, 2013, Pages 343~350
DOI : 10.5657/KFAS.2013.0343
Instant krill gruel was produced using peeled Antarctic krill Euphausia superba as a high nutritional ingredient and the food quality was investigated. The food quality of krill gruel was examined by measuring proximate composition, cholesterol, calorie, Hunter color value, total amino acids, fatty acids, fluoride, viscoelastic properties, and by sensory evaluation. The krill gruel had a moisture content of 87% and a pH of 6.65. The krill gruel contained 51 kcal/100 g, and 0.1% fat and 3.5 mg/100 g cholesterol. Its fatty acid composition exhibited high levels of unsaturated fatty acids. The levels of oleic acid and linolenic acid were high, and n-3, n-6, and n-9 fatty acid contents ranged from 1% to 6%. The total amino acid content was 2132 mg/100 g, and the levels of glutamic acid, aspartic acid, leucine, alanine, and arginine were particularly high. Essential amino acids accounted for over 30% of the total amino acids. Fluoride level in the krill gruel was 3.07 mg/kg. The viscoelastic properties of the krill gruel were determined as 6.28 Pa at shear stress of 2.51 Pa. In the recovery test, the elastic restoring force after deformation was low.
Chromatographic Fractionation of Protease Inhibitors from Fish Eggs
Kim, Jin-Soo ; Kim, Ki Hyun ; Kim, Hyeon Jeong ; Kim, Min Ji ; Park, Sung Hwan ; Lee, Hyun Ji ; Heu, Min Soo ;
Korean Journal of Fisheries and Aquatic Sciences, volume 46, issue 4, 2013, Pages 351~358
DOI : 10.5657/KFAS.2013.0351
A protease inhibitor from fish eggs was fractionated using chromatographic methods. The fractionation efficiency was evaluated in terms of specific inhibitory activity (SIA, U/mg), purity (fold), total inhibitory activity (TIA, U), and recovery (%). The protease inhibitor (PI) from egg extracts of skipjack tuna (ST Katsuwonus pelamis), yellowfin tuna (YT Thunnus albacares) and Alaska pollock (AP Theragra chalcogramma) was fractionated using Sephadex G-50 gel filtration and DEAE-Sepharose CL-6B anion exchange chromatography based on protein size exclusion and net charge, respectively. Fractions exhibiting strong inhibitory activity were contained in the 30-50 kDa fraction on gel filtration and in the range of 0.4-0.7 M NaCl gradient fraction on anion exchange chromatography. The respective TIA and percent recovery of the fraction obtained with gel filtration toward trypsin and
-benzoyl-L-arginine-p-nitroanilide (BAPNA) were 2,758.7 U and 29.6% for ST, 1,005.5 U and 25.6% for YT, and 1,267.5 U and 26.0% for AP. Gel filtration chromatography was more effective at fractionating PI than using ion exchange chromatography. These results suggest that fish eggs act as serine protease inhibitors and might be useful for protease inhibition in foodstuffs.
Effects of Lactobacillus brevis BJ20 Fermentation on the Antioxidant and Antiinflammatory Activities of Sea Tangle Saccharina japonica and oyster Crassostrea gigas
Kang, Young Mi ; Woo, Nam-Sik ; Seo, Yong Bae ;
Korean Journal of Fisheries and Aquatic Sciences, volume 46, issue 4, 2013, Pages 359~364
DOI : 10.5657/KFAS.2013.0359
Inordinate stress causes disorders of various systems in humans and activates defense mechanisms to maintain homeostasis in the body. Sleep is a vital, highly organized process regulated by complex systems of neuronal networks and neurotransmitters. Sleep is an essential biological process whose underlying regulating involves numerous anatomical structures and biochemical substances that can be compromised by stress and by the immune system. Gamma-amino butyric acid (GABA) is the main inhibitory neurotransmitter of the central nervous system, and activation of GABAA receptors is known to favor sleep. This study was conducted to evaluate the possible application of Lactobacillus brevis BJ20 fermentation to improve the functional qualities of sea tangle Saccharina japonica and oyster Crassostrea gigas. Antioxidant activity was determined by assaying levels of radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide. L. brevis BJ20 fermentation of sea tangle and oyster enhanced both antioxidant and antiinflammatory activities. These results suggested that L. brevis BJ20 fermented sea tangle and oyster could be used for alleviation of stress and to promote sleep.
Skin Pigmentation of 0-age and 1-age Red- and White-colored Fancy Carp Cyprinus carpio var. koi Fed Diets Containing Different Amounts of Paprika
Kim, Yi-Oh ; Bang, In Chul ; Lee, Sang-Min ;
Korean Journal of Fisheries and Aquatic Sciences, volume 46, issue 4, 2013, Pages 365~370
DOI : 10.5657/KFAS.2013.0365
This study investigated the effect of dietary paprika on the skin coloration of red- and white-colored fancy carp Cyprinus carpio var. koi, in two age groups: 0-age (
g/fish) and 1-age (
g/fish). Three isonitrogenous diets were formulated to contain 0, 5, and 10% paprika (Con, P5 and P10, respectively). Three replicate groups of 0-age fish and two replicate groups of 1-age fish were fed one of the experimental diets for 9 weeks. Survival, weight gain, and feed efficiency were not significantly affected by the dietary paprika level (P>0.05) at both fish sizes. The dietary paprika level influenced the redness (
), lightness (
), and yellowness (
) of fish skin. The
value of the skin of the fish fed the P5 and P10 diets tended to decrease with feeding period. The skin
value of 0-age fish (small) fed the diets containing paprika increased significantly with feeding period and was higher than that of fish fed the control diet after 3 weeks (P<0.05). However, the
value of 1-age fish (large) fed the diets containing paprika tended to increase slightly with feeding period. At the end of the experiment, the skin total carotenoid level was increased significantly in fish of both sizes fed the P5 and P10 diets compared to fish fed the control diet. Therefore, 5% paprika powder in the diet increases the skin redness of red- and white-colored fancy carp, especially in small fish.
Optimal Dietary Protein and Lipid Levels for Growth of Juvenile Muddy Loach Misgurnus anguillicaudatus
Kim, Kwang Seog ; Lim, Sang Gu ; Bang, In Chul ; Choi, Jin ; Lee, Sang-Min ;
Korean Journal of Fisheries and Aquatic Sciences, volume 46, issue 4, 2013, Pages 371~376
DOI : 10.5657/KFAS.2013.0371
A feeding trial was conducted to determine the optimum dietary protein and lipid levels for the growth of juvenile muddy loach Misgurnus anguillicaudatus. Eight experimental diets (designated as P20L7, P20L14, P30L7, P30L14, P40L7, P40L14, P50L7 and P50L14) were formulated to contain 20%, 30%, 40% and 50% protein with 7% and 14% lipid. Three replicate groups of muddy loach (1.5 g/fish) were fed one of the experimental diets ad libitum for 8 weeks. Survival of fish fed the P20L14 diet was lower than in other groups (P<0.05). Specific growth rate (SGR) and feed efficiency (FE) of fish were affected by dietary protein (P<0.05) and lipid (P<0.005) levels. SGR and FE of fish tended to decrease with increasing dietary lipid level at the same protein level. There were no significant differences in SGR and FE among fish fed diets containing different protein levels ranging from 30% to 50% with the same lipid level. Whole body moisture and lipid contents were affected by dietary protein and lipid levels. Crude lipid content of fish fed the 14% lipid diets was higher than that of fish fed 7% lipid diets at each protein level. The results of this study indicate that a diet containing 30% protein with 7% lipid would be suitable for the optimum growth and effective feed utilization of juvenile muddy loach.
Effect of Dietary Protein and Lipid Levels on the Growth and Body Composition of Juvenile Long Snout Bullhead Leiocassis longirostris Gunther
Lim, Sang Gu ; Han, Hyoung Kyun ; Bang, In Chul ; Choi, Jin ; Lee, Sang-Min ;
Korean Journal of Fisheries and Aquatic Sciences, volume 46, issue 4, 2013, Pages 377~383
DOI : 10.5657/KFAS.2013.0377
We ran a feeding trial to determine optimal dietary protein and lipid levels for growth of juvenile long snout bullhead Leiocassis longirostris Gunther. Eight experimental diets (P20L7, P20L14, P30L7, P30L14, P40L7, P40L14, P50L7 and P50L14) were formulated to contain 20%, 30%, 40% or 50% protein combined with either 7% or 14% lipid. Three replicate groups of fish (mean mass: 3.9 g/fish) were fed one of the experimental diets ad libitum for 8 weeks. Survival of fish fed the P20L14 diet was lower than that of fish fed the P40L14, P50L7 and P50L14 diets. Growth of fish fed diets containing 7% lipid increased with increasing protein level (up to 50% protein); growth of fish fed diets containing 14% lipid increased with increasing protein level (up to 30% protein). The feed efficiency of fish fed a diet with 50% protein and 7% lipid was higher than that of other groups. Whole body moisture and lipid contents were affected by dietary lipid level but not by dietary protein level. The crude lipid contents of fish fed 14% lipid diets were higher than those fed 7% lipid diets across all protein levels (other than the 50% level). Thus, under our experimental conditions, an increase in dietary protein level improved growth and feed efficiency of fish; a diet containing 50% protein with 7% lipid was optimal for growth and effective feed utilization in juvenile long snout bullhead.
Anti-Inflammatory Effect of Ethyl Acetate Fraction Isolated from Undaria pinnatifida on Lipopolysaccharides-Stimulated RAW 264.7 Cells
Choi, Min-Woo ; Kim, Jae-Il ;
Korean Journal of Fisheries and Aquatic Sciences, volume 46, issue 4, 2013, Pages 384~392
DOI : 10.5657/KFAS.2013.0384
An ethanolic extract of Undaria pinnatifida was fractionated using several solvents. Of the fractions, the ethyl acetate fraction had the greatest inhibitory effect on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW 264.7 macrophage cells. Using this fraction (U. pinnatifida ethyl acetate extract, UPE), we investigated the molecular mechanism underlying its inhibitory effect on LPS-stimulated RAW 264.7 cells. Pretreatment of the cells with up to
UPE significantly inhibited NO production and inducible nitric oxide synthase (iNOS) expression, in a dose-dependent manner. Similarly, UPE treatment markedly reduced the production of pro-inflammatory cytokines, such as interleukin (IL)-1, IL-6 and tumor necrosis factor-
), while it strongly suppressed the nuclear translocation of nuclear factor-kappa B (NF-
) by preventing proteolytic degradation of inhibitor of nuclear factor
. Moreover, UPE treatment significantly reduced the phosphorylation of phosphatidylinositol 3-kinase (PI3K)/Akt and mitogen-activated protein kinase (MAPK) in LPS-stimulated cells. These results indicate that UPE contains anti-inflammatory compounds and suggest that it might be used as a functional food material that assists in prevention of inflammatory diseases.
The Rotifer Brachionus calyciflorus and Water Flea Moina macrocopa as Alternative Foods for Production of the Fighting Fish Betta splendens
Kwon, O-Nam ; Park, Kie Young ; Park, Heum-Gi ;
Korean Journal of Fisheries and Aquatic Sciences, volume 46, issue 4, 2013, Pages 393~398
DOI : 10.5657/KFAS.2013.0393
The purpose of this study was to determine how an ornamental fish, such as the fighting fish, Betta splendens would respond to the use of freshwater live-prey, such as rotifers Brachionus calyciflorus and water fleas Moina macrocopa. Ingested quantity, digestive velocity and somatic growth were compared between larvae fed a freshwater rotifer and those fed boiled yolk. Food efficiency and somatic growth were compared between larvae that were fed freshwater water fleas and those fed a micro-diet developed for flounder (
, I-hwa Ltd.). The number of rotifers ingested by larvae reached a maximum of 191 per day. However, based on the number ingested per hour and the digestive velocity of consumed rotifers, the maximum ingestible and digestible number of rotifers was calculated to be 272 per day. A maximum of 67 individuals (mean, 49.8 individuals) could be completely digested within the 1-h period from 90 to 180 min after feeding. Somatic growth was enhanced in larvae that were fed rotifers compared to those fed boiled yolk. Larvae exhibited greater growth at rotifer densities of 30 and 40 per mL than at lower densities. Among the water-flea (M. macrocopa and Bosmina sp.) and micro-particle diets, feeding with M. macrocopa resulted in the greatest somatic growth of larvae during the water-flea feeding stage.
Effects of Dietary Supplementation of a Citrus By-product on Growth Performance, Innate Immunity and Tolerance of Low Water Temperature in Red Seabream Pagrus major
Song, Jin-Woo ; Park, Sang-Hyeon ; Lee, Cho-Rong ; Lee, Kyeong-Jun ;
Korean Journal of Fisheries and Aquatic Sciences, volume 46, issue 4, 2013, Pages 399~406
DOI : 10.5657/KFAS.2013.0399
Our aim was to determine the effects of a citrus by-product (CBP) and CBP fermented by Lactobacillus plantarum (LP-CBP), provided as dietary supplements, on the growth performance, feed utilization, innate immunity and temperature tolerance of red seabream. A diet without inclusion of CBP or LP-CBP was used as a control and four other experimental diets were formulated to replace wheat flour by 4% and 8% of either CBP or LP-CBP (designated as Con, LP-CBP4%, LP-CBP8%, CBP4% and CBP8%, respectively). Experimental diets were fed to triplicate groups of 25 fish (initial body weight, 55.0 g) for 9 weeks. Growth performance and feed utilization were not significantly different among all the groups. Bone collagen content was significantly increased by supplementation with CBP and LP-CBP. Vitamin C concentration tended to be higher in livers of fish fed the supplements than in the control group. Myeloperoxidase, lysozyme and superoxide dismutase activities were higher in fish fed CBP or LP-CBP than in fish fed the control diet. When fish were exposed to low water temperature, cumulative mortalities of those fed CBP or LP-CBP supplemented diets were lower (29%, 33%, 34% and 33% mortalities for LP-CBP4%, LP-CBP8%, CBP4% and CBP8%, respectively) than in the control group (58%). Therefore, inclusion of either CBP or LP-CBP at up to 8% in red seabream diet brings benefits through enhanced innate immunity and better tolerance of low water temperature.
Effect of Food Particle Size, Stocking Density and Feeding Frequency on the Growth Performance of Juvenile Korean Rockfish Sebastes schlegelii
Oh, Dae-Han ; Song, Jin-Woo ; Kim, Min-Gi ; Lee, Bong-Joo ; Kim, Kang-Woong ; Han, Hyon-Sob ; Lee, Kyeong-Jun ;
Korean Journal of Fisheries and Aquatic Sciences, volume 46, issue 4, 2013, Pages 407~412
DOI : 10.5657/KFAS.2013.0407
We performed four sets of feeding trials to establish optimum feed size (Exp-I), stocking density (Exp-II) and feeding frequency (Exp-III and IV) for Korean rockfish. In Exp-I, three different particle sizes of a commercial diet (small, 2.0-2.1 mm; medium, 2.4-3.2 mm; and large, 4.0-5.3 mm) were fed to four replicate groups of fish (
), each of which was fed to apparent satiation for six weeks. In Exp-II, fish (
) were reared at four stocking densities (1.5, 3.0, 4.5 and 6.0
) and fed a commercial diet to apparent satiation for four weeks. In Exp-III, fish (
) were fed a commercial diet once, twice, thrice,
a day at a feeding ratio of 3.25% of body mass. Another group of fish was fed the same commercial diet
a day to apparent satiation; this treatment was designated FS (five times satiation/day). In Exp-IV, fish (
) were fed a commercial diet once, twice, thrice or
a day to apparent satiation. Another group of fish was fed to apparent satiation once every 48 hours. In Exp-I, fish fed the large particle (4.0-5.3 mm) diet had a significantly higher feed conversion ratio and lower protein efficiency ratio than fish fed the small particle diet. In Exp-II, groups of fish reared at densities of 4.5 and 6.0
had significantly higher feed intake and growth performance than fish reared at 1.5 and 3.0
. In Exp-III, fish fed to apparent satiation had significantly higher growth performances than fish fed once or
a day. A significantly higher feed conversion ratio and a lower protein efficiency ratio were obtained in the FS group. In Exp-IV, growth performance and feed utilization efficiency were not significantly affected by experimental variation in feeding frequency. Fish fed to apparent satiation once every 48 hours had better feed utilization than those in other treatments and growth performances of those were comparable. Therefore, the optimum feed particle size, stocking density and feeding frequency for Korean rockfish under conditions we used were 2.0-3.2 mm, 4.5-6.0
, and once a day or once every 48 hour, respectively.
Community Structure and Distribution Pattern of the Pleuronectiform Fishes in the Uljin Marine Ranching Area, Korea
Yoon, Byoung Sun ; Park, Jeong-Ho ; Sohn, Myong Ho ; Yang, Jae Hyeong ; Yoon, Sang Chul ; Choi, Young Min ;
Korean Journal of Fisheries and Aquatic Sciences, volume 46, issue 4, 2013, Pages 413~423
DOI : 10.5657/KFAS.2013.0413
To elucidate the variation of species composition, biomass and length distribution of flatfishes by the period and region in the Uljin marine ranching area, bottom trawl survey was investigated at the six stations from Feb. 2008 to Dec. 2010. During the survey period, a total 4 families 17 species in the Pleuronectiformes, average 69,158
were identified, in 2008 appeared in 14 species, average 25,798
and in 2009 appeared in 13 species, average 102,360
and in 2010 appeared in 14 species, average 75,704
. The individual dominant species, occupying over 10% of total individuals, was Pleuronectes herzensteini (20,811 ind., 30.0%), Hippoglossoides pinetorum (18,666 ind., 26.9%) and Glyptocephalus stelleri (13,499 ind., 19.4%) also the biomass dominant species, occuping over 10% of total biomass, was P. herzensteini (2,207 kg, 39.3%), Pleuronectes yokohamae (857 kg, 15.3%), H. pinetorum (761 kg, 13.5%), Kareius bicoloratus (677 kg, 12.1%). From the cluster and MDS analysis based on Bray-Curtis similarity matrix of fourth root transformed data of species number and individuals in the Uljin marine ranching area from Feb. 2008 to Dec. 2010 was divided into two different groups of the flatfishes community in 2008 and from Jan. to Apr. in 2009 and 2010 (Group A) and the pleuronectiform community in from May to Dec. in 2009 and 2010 (Group B). From the cluster and MDS analysis using the similarity of demersal organisms community among six stations, the Uljin marine ranching area was divided into two different groups of Group 1 (St. 1 and St. 3) and Group 2 (St. 2, St. 4, St. 5 and St. 6).
Organic Enrichment and Pollution in Surface Sediments from Shellfish Farming in Yeoja Bay and Gangjin Bay, Korea
Choi, Minkyu ; Kim, Hyung Chul ; Hwang, Dong-Woon ; Lee, In-Seok ; Kim, Young-Sook ; Kim, Ye-Jung ; Choi, Hee-Gu ;
Korean Journal of Fisheries and Aquatic Sciences, volume 46, issue 4, 2013, Pages 424~436
DOI : 10.5657/KFAS.2013.0424
Organic enrichment was investigated in surface sediments from the Yeoja and Gangjin Bays of Korea, which contain dense shellfish farms, in order to evaluate the contamination status and temporal changes in shellfish farming along these coasts. The degree of organic enrichment was determined using geochemical indicators (chemical oxygen demand, ignition loss, acid volatile sulfide, total organic carbon in sediments, and total nitrogen in sediments, ammonium and nitrate in pore water, and bioluminescence inhabitation for sediments). Temporal changes in organic enrichment conditions were detected by comparing our 2012 data to those previously reported from a survey conducted in 1999/2000. Organic enrichment was significantly higher in September than in May and July, in Gangjin Bay than in Yeoja Bay, and significantly higher in shellfish farms than in reference sites not used to culture shellfish. Ammonium concentrations in pore water were two orders of magnitude greater than nitrate concentrations, suggesting that these bays represent nitrogen-reducing environments.
Sterols as Indicators of Fecal Pollution in Sediments from Shellfish Farming Areas (Yeoja Bay and Gangjin Bay) of Korea
Choi, Minkyu ; Lee, In-Seok ; Hwang, Dong-Woon ; Kim, Hyung Chul ; Kim, Ye-Jung ; Kim, Sook-Yang ;
Korean Journal of Fisheries and Aquatic Sciences, volume 46, issue 4, 2013, Pages 437~444
DOI : 10.5657/KFAS.2013.0437
Eight fecal sterols were analyzed in surface sediments collected from shellfish farming areas in Yeoja Bay and Gangjin Bay, Korea, to evaluate sewage-derived fecal pollution. The concentrations of coprostanol, a good marker of sewage-derived organic contamination, in sediments were in the range of 10-530 ng/g-dry in Yeoja Bay, and 10-190 ng/g-dry in Gangjin Bay. Coprostanol levels were markedly higher in the inner bay than in the outer bay. These levels were lower than those reported in urbanized bays in Korea, however, they were comparable to levels in other shellfish farming areas including Gamak Bay. A multivariate analysis of the ratios of other sterols suggested that the sterols originated from sewage and plankton/benthos. Sewage was the dominant source at stations located close to the river mouth and wastewater treatment plant (WWTP) outfalls, and plankton/benthos was the primary source in the outer bay. These results suggest that management of point sources, e.g., WWTP as well as non-point sources, e.g., riverine inputs is important for improving the water quality in Yeoja Bay and Gangjin Bay.
Size-class Estimation of the Number of Walleye Pollock Theragra chalcogramma Caught in the Southwestern East Sea during the 1970s-1990s
Kang, Sukyung ; Park, Jung Ho ; Kim, Suam ;
Korean Journal of Fisheries and Aquatic Sciences, volume 46, issue 4, 2013, Pages 445~453
DOI : 10.5657/KFAS.2013.0445
Walleye pollock Theragra chalcogramma fisheries in Korean waters have changed dramatically during the last three decades: the highest catches occurred in 1981, followed by continuous decreases through the 1990s, ending with a complete collapse of the population in the 2000s. The major spawning ground of walleye pollock is located in North Korean waters, and some juveniles (called nogari in Korean, <300 mm) migrate to the south for feeding and growth. Since the 1960s, Korean fishermen have often caught juveniles, and the weight (metric tons) of juvenile catch was recorded from 1975-1997. However, because the walleye pollock were not aged, the population age structure was not delineated. We developed a model to estimate the number of walleye pollock of each size class based on catch statistics of adults and juveniles, the catch proportion of each size class, and length and weight information on specimens collected by Danish-seine and drift-gill-net fisheries. The model results demonstrated that the recruitment size of walleye pollock was consistently within the 200-250mm size class, and the highest number of this size class occurred in 1981, although values greatly fluctuated interannually. The number of juvenile pollock was 10.4 times higher than that of adult pollock during 1975-1997. The total yield of juvenile pollock was 0.95 million tons, which was equivalent to about 68.2% of total pollock production. The number of juvenile pollock caught during the same period, however, was 16 billion, comprising about 91.2% of the total number caught. Such high fishing pressure on juvenile pollock is considered one of the main factors causing the collapse of the pollock population.
Distributions of Organic Matter and Trace Metals in Intertidal Surface Sediment from the Mokpo-Haenam Coast
Hwang, Dong-Woon ; Kim, Pyoung-Joong ; Jung, Rae-Hong ; Yoon, Sang-Pil ;
Korean Journal of Fisheries and Aquatic Sciences, volume 46, issue 4, 2013, Pages 454~466
DOI : 10.5657/KFAS.2013.0454
To evaluate the organic matter and trace metal pollution in intertidal sediment of the coastal zone, various geochemical parameters (grain size, ignition loss [IL], chemical oxygen demand [COD], acid volatile sulfide [AVS], and metals [Al, Fe, Cu, Pb, Zn, Cd, Cr, Mn, Hg, and As]) were measured for the intertidal surface sediment of the mainland and islands between Mokpo and Haenam in the southwestern coast of Korea. The surface sediments consist mainly of finer sediments, such as mud and silt. The concentrations of IL, COD, and trace metals in intertidal sediment were relatively high in the shoreline of the mainland than in that of islands and those in some stations exceeded the sediment quality guidelines (SQGs). Moreover, the concentrations of IL, COD, and trace metals (except As) in sediment showed relatively good positive correlations with mean grain size, indicating that the concentrations of organic matter and trace metals in intertidal sediment of the study region are dependent on grain size of sediment. Pollution evaluation for trace metals using geochemical assessment techniques, such as enrichment factor, geoaccumulation index, and SQGs, suggested that the intertidal sediments in the study region show light pollution with Cr and moderate pollution with As. More extensive interdisciplinary studies are required to determine the potential causes of As pollution in intertidal sediment.
Literature Survey on the Phytoplankton Flora in the Nakdong River Estuary, Korea
Chung, Ik Kyo ; Kim, Nam Lim ; Song, Eun Hye ; Lee, Jee Eun ; Lee, Sang-Rae ;
Korean Journal of Fisheries and Aquatic Sciences, volume 46, issue 4, 2013, Pages 467~487
DOI : 10.5657/KFAS.2013.0467
Long-term and systematic monitoring of phytoplankton is important, as phytoplankton serve as indicators of water quality status in aquatic environments. In the present study, the plankton community structure of the Nakdong River estuary over the past 30 years was investigated by literature survey to provide references for the occurrence of planktonic species. A total of 876 species from 18 taxonomic lineages were reported and, among them, 569 species were identified to occur seasonally at the Mulgeum, Seonam and Eulsukdo sites. Diatoms and chlorophytes were dominant in the microscopic studies. The 54 species at the Mulgeum and the 96 species at the Eulsukdo sites have not been reported since the river barrage construction in 1987. The majority of reports speculate that there has been a change in the aquatic environment, particularly the plankton community structure, due to operation of a river barrage since 1987.