• Journal of Aquaculture
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• v.22 no.1
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• pp.11-15
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• 2009

Effect of fasting and refeeding on growth and blood chemistry of juvenile olive flounder Paralichthys olivaceus L. was investigated when fish achieved compensatory growth. Fish were fed the experimental diet for 6 days a week. Five treatments in triplicate were prepared: C, S1, S2, S3 and S4. Fish in the control group (C) were hand-fed to apparent satiation twice a day. Fish in treatments of S1, S2, S3 and S4 experienced 1, 2, 3 and 4 weeks of starvation and were then hand-fed to satiation twice daily during the remaining 7, 6, 5 and 4 weeks of the experiment, respectively. Weight gain of fish in C, S1 and S2 were higher than those of fish in S3 and S4. A significant difference in plasma total protein, glucose, triglyceride, $T_3$ and $T_4$ was observed in between starved and refed fish for the rest periods of the feeding trial. Plasma total protein and $T_3$ of flounder decreased with week of fasting and following correlationships were obtained; Y (Total protein) = -0.13X (week of fasting) + 1.54, $R^2=0.9792$ and $Y(T_3)=-11.48X$ (week of fasting) + 79.57, $R^2=0.8822$, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.4
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• pp.445-453
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• 2013

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.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.5
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• pp.550-555
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• 1999

The growth and spawning time of juvenile Ammodytes personatus were analyzed based on the daily growth increment in otolith reading of the sample caught in the coastal waters of Shinsudo, Sacheon from March 20 to May 1, 1988. Daily growth increment in otolith was formed once a day. The estimated spawning time ranged from November, 1987 to March, 1988. The von Bertalanffy growth model and the Gompertz growth model were expressed as, $TL=87.80(1-e^{-0.0074(t+10.79)})$ and $TL=72.59 e^{-1.8417\;e-0.0152t}$ respectively, where TL is total length in mm, t is age in day.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.5
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• pp.690-699
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• 2014

Three feeding trials were conducted to evaluate the effects of feeding rate and water temperature on growth and body composition of juvenile Korean rockfish, Sebastes schlegeli rearing at 3 different water temperatures. A total of 270 fish (each experiment) individual body weight (BW) averaging $16{\pm}0.3g$ ($mean{\pm}SD$) were fed a commercial diet for 4 wk at $16^{\circ}C$, $20^{\circ}C$, and $24^{\circ}C$. At each temperature, triplicate tanks were assigned to one of 6 feeding rates: 1.5%, 2.5%, 2.8%, 3.1%, 3.4%, and satiation (3.7% BW/d) at $16^{\circ}C$, 1.9%, 2.9%, 3.2%, 3.5%, 3.8% and satiation (4.1% BW/d) at $20^{\circ}C$ and 1.7%, 2.7%, 3.0%, 3.3%, 3.6%, and satiation (3.9% BW/d) at $24^{\circ}C$ water temperature. Weight gains of fish in satiation and 3.4% groups at $16^{\circ}C$, in satiation and 3.8% groups at $20^{\circ}C$ and in satiation and 3.6% groups at $24^{\circ}C$ were significantly higher than those of fish in the other treatments (p<0.05). A broken line regression analysis of weight gain indicated that optimum feeding rates of juvenile Korean rockfish were 3.41% at $16^{\circ}C$, 3.75% at $20^{\circ}C$ and 3.34% at $24^{\circ}C$ water temperature. Results of the present study indicate that the optimum feeding rate could be >3.1% but <3.41% at $16^{\circ}C$, >3.5% but <3.75% at $20^{\circ}C$ and >3.0% but <3.34% at $24^{\circ}C$. As we expected results suggest that fish performed better at $20^{\circ}C$ than $16^{\circ}C$ or $24^{\circ}C$ water temperature and the optimum feeding rate could be 3.1% BW/d to 3.7% BW/d in 16 g of juvenile Korean rockfish.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.3
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• pp.227-233
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• 2014

We designed a 16-week feeding experiment to test the effects of dietary supplementation with distillers' dried grain (DDG) on the growth, feed utilization, and body composition of juvenile muddy loach Misgurnus anguillicaudatus. Seven isonitrogenous and isocaloric diets were formulated to contain 0% DDG (Control); 10%, 20%, and 30 % DDG from rice (diets RM10, RM20 and RM30); and 10%, 20%, and 30% DDG from rice and wheat flour (diets RWM10, RWM20 and RWM30), respectively. Three replicate groups of juvenile muddy loach averaging $1.5{\pm}0.10$ g were fed one of the diets to satiation twice daily. Survival of juvenile muddy loach fed the RWM20 and RWM30 diets was higher than that of the control group (P<0.05), while weight gain tended to decrease when fish were fed diets containing DDG. Weight gain of fish fed the RWM10 diet was greater than that of fish fed other diets, but the RM30 diet resulted in less weight gain than did the control (P<0.05). The feed and protein efficiency ratios of fish fed the RM10, RM20, RM30, RWM10, RWM20 and RWM30 diets were all similar to the control (P>0.05). Neither daily feed intake nor proximate composition of the whole body was affected by dietary DDG (P>0.05). The compositions of isoleucine, leucine, lysine, threonine, and valine were all elevated in fish fed the RM30, RWM10, RWM20 and RWM30 diets relative to those of other groups (P<0.05). In contrast, methionine + cystine and phenylalanine + tyrosine were all lower in fish fed the RM30, RWM10, RWM20 and RWM30 diets, as compared to those of other groups (P<0.05). Our results suggest that DDG is suitable as a partial replacement for soybean meal and wheat flour, and could be used at a rate of up to 20% for rice, or 30% for rice and wheat flour, for optimum growth performance of juvenile muddy loach.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2002.05a
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• pp.283-285
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• 2002

• Proceedings of the Korean Aquaculture Society Conference
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• 2004.05a
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• pp.217-219
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• 2004

• Proceedings of the Korean Aquaculture Society Conference
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• 2002.08a
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• pp.174-176
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• 2002

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 1998.06a
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• pp.303-304
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• 1998

• Journal of the Korean Society of Environmental Restoration Technology
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• v.18 no.3
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• pp.79-95
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• 2015

To suggest ecological management plans for invasion of Salix gracilistyla, stepwise environmental sieve of seed dispersal, germination, seedling and juvenile stages were investigated. About 84% of total seeds were released between May 6 and 10. Germination rates significantly declined with decrease of light intensity from 100% to 30% and 0% (p<.001), but above 60% of seeds germinated in all treatments. Difference of germination rates with 0 and 2cm water level was not significant (p = .571). With increase of elapsed time after seed dispersal, germination rates significantly decreased (p<.001), and seed viability was lost within 16 days. Considering both germination rate of seed and survival rate of seedling, survival rate of all dispersed seeds was only 5% when 8 days passed after seed dispersal. All 22-day-old seedlings (height: 1cm) died under flooding of twice level as its height. With decrease of light intensity from 100% to 30%, survival rates of seedling decreased from 90% to 33% (p<.001). In the case of 45-day-old juvenile (height: 20cm), survival rate was 70% under the water level same as its height. There was significant interactive effect of water level and light intensity on the growth of juvenile (height: p<.001, dry weight: p<.01), and survival rate of juvenile was 10% under +20cm-water level and 30%-light intensity condition. The following management plans for invasion of S. gracilistyla are recommended from these results. (1) Dry condition should be maintained at fringe of wetlands for about two weeks at seed dispersal and germination stage (early May~mid May). (2) Water level should be raised to about 5cm at fringe of wetlands for about two weeks at seedling stage (mid May~early June). (3) Water level should be raised to over 20cm at fringe of wetlands for a long time at juvenile stage. Planting trees for shading can raise management effectiveness (mid June~). (4) As water level manipulating is performed as fast as possible for controlling seedling and juvenile, management become easier and more effective.