• Fisheries and Aquatic Sciences
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• v.26 no.6
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• pp.367-379
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• 2023

The rapid expansion of shrimp production requires a huge amount of protein sources from soybeans and wild-caught fishmeal; both are becoming a shortage. Meanwhile, catfish production and processing is a giant industry in Vietnam, which produce hundred thousand tonnes of protein- and lipid-rich by-products, annually. Using catfish by-products to gradually replace the traditional protein sources in shrimp aquaculture may bring triple benefits: 1) reducing pressure on wild fish exploitation for fishmeal, 2) reducing the environmental impacts of catfish by-products, and 3) increasing the value and sustainability of aquaculture production. In this study, we used catfish by-products to produce fish protein hydrolysate (FPH) and nano-hydroxyapatite (HA) as additives in feed for Pacific white shrimp (Litopenaeus vannamei). The supplement mixture of FPH and HA was added into the commercial diet (Charoen Pokphand Group [CP], 38% protein, and 6.5% lipid) to reach 38%, 38.5%, 40%, 43%, and 44% of the crude protein content. The survival and growth of shrimps were weekly assessed to day 55. The results showed that the shrimp growth was highest at 43% crude protein content in the feed as indicated by an increase of 124% and 112% in shrimp weight and length, respectively, compared to the commercial reference diet. No negative effects of adding the mixture of FPH and HA on the water quality were observed. Vibrio density was lower than 6.5 × 10³ CFU/mL, which is the lowest Vibrio density negatively affecting the shrimp growth and development. These findings indicate that the mixture of FPH and HA are promising additive components in feed for post-larval shrimp L. vannamei diets.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.6
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• pp.769-776
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• 2013

This study evaluated fermented soybean meal (FSM) as a fish meal (FM) replacement and determined the appropriate amount of FSM in juvenile olive flounder diet. Twenty-four aquaria with a flowing-water system were stocked with fish averaging 20.9 g at a density of 25 fish/tank. Five experimental diets were prepared replacing FM with 0, 10, 20, 30, or 40% FSM based on FM protein (designated $FSM_{0}$, $FSM_{10}$, $FSM_{20}$ $FSM_{30}$, and $FSM_{40}$, respectively). Two additional diets were prepared that replaced 30 or 40% of the FM with FSM with added amino acids (methionine and lysine) (designated $FSM_{30+AA}$, and $FSM_{40+AA}$, respectively). Fish (triplicates) were fed one of the eight experimental diets (50% crude protein and 16.7 kJ available energy $g^{-1}$ diet) for 8 weeks. Survival did not differ among the treatments during the feeding experiment. There were no significant differences in weight gain (WG) or specific growth rate (SGR) among the fish fed diets with up to 30% of the FM replaced. However, fish fed $FSM_{40}$ or $FSM_{40+AA}$ had a reduced WG and SGR, as compared to $FSM_0$ (control) (P < 0.05). The feed efficiency and apparent digestibility showed a similar trend (P < 0.05). The proximate composition in the whole body of fish differed only between the control and $FSM_{40}$ for the crude protein level and between the control and $FSM_{30+AA}$ for the crude lipid level. The whole-body amino acid composition did not differ among treatments. No significant differences were found between the diet groups with and without amino acid supplementation, indicating that amino acid supplementation had no effect. The major finding of this study is that fermented soybean meal may replace up to 30% of fish meal without amino acid supplementation for normal growth of juvenile olive flounder.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.6
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• pp.824-831
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• 2014

This study was conducted to investigate the effects of fishmeal replacement with acid-concentrated soybean meal (ACSBM) on growth performance, blood biochemistry, and ingredient digestibility in juvenile olive flounder Paralichthys olivaceus. Six experimental diets were formulated to replace fishmeal protein with ACSBM at 0%, 20%, 30%, 40%, 50%, and 60% (designated ACSBM0, ACSBM20, ACSBM30, ACSBM40, ACSBM50, and ACSBM60, respectively). Triplicate groups of fish (initial fish mean weight: $14.3{\pm}0.03g$) were fed the experimental diets to apparent satiation (twice daily at 08:00 and 18:00 h). After a 12-week feeding trial, a total of 180 healthy fish were randomly distributed into three Guelph system tanks at a density of 60 fish/tank (initial fish mean weight : $50.6{\pm}2.4g$) to test the apparent digestibility coefficients of the ingredients (ACSBM, fishmeal, and soybean meal). Although negative effects were observed with ACSBM40, ACSBM50 and ACSBM60 after 12 weeks of feeding, up to 20% of the fishmeal protein could be successfully replaced with ACSBM without significant growth depression. Hemoglobin and hematocrit values of fish fed the ACSBM50 and ACSBM60 diets were significantly lower than those of fish fed the ACSBM0 diet. Glucose values of fish fed the ACSBM60 diet were significantly higher than those of fish fed the ACSBM0 and ACSBM20 diets. Digestibility of protein in ACSBM and soybean meal was 85.9% and 82.5%, respectively. Results indicated that at least 20% of fishmeal protein can be replaced by ACSBM in diets of juvenile olive flounder without supplementation of limiting amino acids.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.4
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• pp.457-468
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• 1995

In order to develop a more practical culture system from the present running seawater tank system, two experiments of environmental factors, growth, survival rate and rearing density of olive flounder (Paralichthys olivaceus) were carried out for two consecutive years. Two groups of fish in initially averaging 7.5cm of total length, and 3.4g of body weight (EXP. I) and 5.0cm and 1.8g (EXP. II) were reared in the semi-closed recirculating seawater system equipped with the rotating biological contactors with the commercial culture scale. The dissolved inorganic nitrogen concentrations is EXP. I ranged 0,247-0.512 ppm of $NH_4-N$ (0.010-0.043 ppm of$NO_2-N$, and 0.108-0.342 ppm of $NO_3-N$, and those in EXP. II were 0.091-0.715 ppm, 0.002-0.045 ppm, and 0.007-0.277 ppm, respectively. Daily feeding rates of the fish were $0.67-2.41\%$ in EXP. I and $0.69-2.22\%$ in EXP_ II, and teed efficiency were $34.8-59.8\%\;and\;40.5-88.4\%$ in EXP. I and II, respectively. The average total ten說h and body weight were 40.0-42.8cm and 695.0-852.69g after 340 days culture in EXP. I, and 36.7-39.7cm and 552.4-706.4 g after 365 days culture in EXP. II, respectively. Survival rates of the fish at the end of EXP. I and II were $92.0\%\;and\;96.0\%,$ respectively. The ratio to body surface area of non-ocular side in all fish to bottom area of rearing tank, so-called covering rate, was used as an indicator of rearing density. The highest cowering rate and weight density of fish per $m^2$ of rearing tank at the end of experimental period were 2.2 and 34.1kg in EXP. I, and 2.6 and 36.3kg in EXP. II, respectively. For the commercial culture of olive flounder, the semi-closed recirculating seawater system was found to be more effective than the running seawater tank system in aspect to the fish productivity and protection of marine environment.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.2
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• pp.217-225
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• 1998

This study was performed to compare the effects of a fish cage on the structure of meiobenthic communities at two locations during May, 1996. The number of meiofaunal taxa at the existing cage site and control site was 15 and 26, respectively. Nematoda was the most dominant group of meiobenthos. Nematoda and Sarcomastigophora comprised more than $90\%$ of total meiofauna at both sites. The total density of control site was 7,702 inds./$10\;cm^{2}$ which is 10 times more than that of fish cage site. The density was highest in the upper 1 cm and decreased with sediment depth. The nematodes/harpacticoid copepods ratio as an index of pollution monitoring for benthic ecosystem at fish cage site was two times higher than at control site. Kinorhyncha known to be sensitive to pollution stress was not found at fish cage site.

• Fisheries and Aquatic Sciences
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• v.25 no.8
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• pp.409-416
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• 2022

This study aims to know the effect of water-extracted horseradish Moringa oleifera leaf and KW21 fertilizer combination application on the density of Nannochloropsis sp. It was conducted in the Natural Food Laboratory of State Polytechnique, Tual. The experiment used complete randomized design with 5 treatments and 3 replications: A (25% horseradish leaf extract + 75% KW21), B (50% horseradish leaf extract + 50% KW21), C (75% horseradish leaf extract + 25% KW21), D (positive control of 100% KW21), and E (negative control of 100% horseradish leaf extract). Results showed that Treatment C yielded the best result, both the highest density of Nannochloropsis sp. and suitable harvest time.

• Ocean Science Journal
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• v.42 no.1
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• pp.41-48
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• 2007

We investigated the temperature and salinity effects on the major fish species in the wintering grounds based on trawl surveys and oceanographic observations in the southwestern waters of Korea during March-early April in 2002-2003. The influence area of warm Kuroshio water was limited to the southwestern area of Korea in 2003 with a range of $7.7-16.3^{\circ}C$, 32.54-34.70 of salinity, wider than that of 2002. The number of fish species and density of major fish species in 2003 were higher than in 2002. Geographical estimation showed high proportions of species number and catches in the areas around Jeju Islands, southwestern waters and the southeastern coast of Korea. Five species; silver pomfret (Pam pus echinogaster), hairtail (Trichiurus lepturus), anchovy (Engraulis japonicus), Small yellow croaker (Larimichthys polyactis) and yellow goosefish (Lophius litulon) were most abundant, composing above 60% of the total catch in 2002 and 2003. More than 50% of catch in the major fish species were mostly distributed in the range of $9.5-11.0^{\circ}C$ of temperature and 33.1-33.9 of salinity. Non-parametric estimation for the major species showed the 1st mode around $10^{\circ}C$ and the 2nd mode at $8-9^{\circ}C$ in 2002 and $11-14^{\circ}C$ in 2003. Among major fish species, hairtail was principally composed of juveniles, and larger individuals were caught in southeastern waters. These results are considered to be helpful for the area-based fishery management strategy for the wintering grounds of the Yellow Sea and coastal waters of Korea.

• Journal of the Korean Professional Engineers Association
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• v.17 no.3
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• pp.22-31
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• 1984

Sardine ant mackerel so called dark muscled fish have been underutilized due to the disadvantages in bloody meat color, high content of fat, and postmortem instability of protein. Recent efforts were made to overcome these defects and develope new types of product such as texturized protein concentrates and dark muscle eliminated minced fish. Approach of this study is based on the rapicl dehydration of foamed fish-starch paste by dielectric heating. In process comminuted sardine meat was washed more than three times by soaking and decanting in chilled water and finally centrifuged. The meat was ground in a stone mortar added with adequate amounts of salt, foaming agent, and other ingredients for aid to elasticity and foam stability. The ground meat paste was extruded in finger shape and heated in a microwave oven to give foamed, expanded, and porous solid structure by dehydration. Dielectric constant ($\varepsilon$′) and dielectric loss ($\varepsilon$") vcalues of sardine meat paste were influenced by wavelength and moisture level. Those values at 100KHz and 15MHz were ranged 2.25∼9.86 ; 2.22∼4.18 for $\varepsilon$′ and 0.24∼19.24 ; 0.16∼1.25 for $\varepsilon$", respectively, at the moisture levels of 4.2∼13.8％. For a formula for fish-starch paste preparation, addition of 20∼30% starch (potato starch) to the weight of fish meat, 2∼4% salt, and 5∼10% soybean protein was adequate to yield 4∼5 folds of expansion in volume when heated. Addition of egg yolk was of benefit to micronize foam size and better crispness. In order to provide better foaming and dehydration, addition of 0.2∼0.5% sodium bicarbonate foaming agent, was proper to result in foam size of 0.5∼0.7mm and foam density of 200∼400/$\textrm{cm}^2$ which gave a good crispness.

• Journal of Korean Society on Water Environment
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• v.29 no.2
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• pp.196-203
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• 2013

Seungchon Weir was constructed in 2010 on the downstream region of Yeongsan River watershed for four major river projects. The purpose of our study was to determine whether fish compositions and distributions differ between the upper ($U_w$) and lower regions ($L_w$) of Seungchon Weir during May - December 2011 along with hydroacoustic fish surveys using Eco-Sounder monitoring ($E_SM$) technique. Total number of fish species sampled by conventional fish sampling at all sites was 29, and 21 and 24 species occurred in the $U_w$ and $L_w$, respectively. Most dominant species was Hemiculter eigenmanni (43%) in the $U_w$ and Opsaiichthys uncirostris amurensis (21%) in the $L_w$, indicating a distinct differences of the species composition. According to hydroacoustic approach of ESM, fish density was significantly higher (p < 0.05) in the $L_w$ section of 250 m than any other sections, This outcome indicates that fishes moving toward the upstream were blocked by weir construction. According to analysis of tolerance guilds, tolerant species (TS) were made of 88% and 79% in the $U_w$ and $L_w$ region, respectively, while the proportions of sensitive species were < 0.1% of the total in the both regions. Trophic guild analysis showed that the proportion of omnivore species were 58% and 40% in the $U_w$ and $L_w$ region, respectively, while insectivores were made of 16% and 21% in the $U_w$ and $L_w$ region, respectively. Both analyses of tolerance guilds and trophic guilds indicate the biological degradation of the waterbody. Fish community structure analysis, based on species diversity, dominance, and evenness indices, showed higher community stability in the $L_w$ region than $U_w$ region. Exotic species of largemouth bass were largely increased in this survey (14%), compared to the past (< 1%), indicating a modification of fish trophic structure.

• Ocean and Polar Research
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• v.37 no.4
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• pp.333-340
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• 2015

The contrast (fish body to medium ratio) of density and sound speed were measured to estimate acoustic scattering from small juvenile cod (Gadus macrocephalus) with the Kirchhoff-Ray Mode backscatter model. The density contrast was measured by the density-bottle method and the sound speed contrast was estimated by the time of flight method. The results revealed that the measured density contrasts of juvenile cod varied between 1.003 and 1.029 (mean = 1.014, S.D. = 0.01). On the other hand, sound speed contrasts varied between 1.039 and 1.041 (mean = 1.041, S.D. = 0.001). The relationship between averaged target strength (TS) and total length (TL) established by the model were <$TS_{38kHz}$> = 20log(TL) - 68.8 and <$TS_{38kHz}$> = 20log(TL) - 69.4, respectively.