• Fisheries and Aquatic Sciences
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• 제20권11호
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• pp.30.1-30.10
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• 2017

Small-scale fish farmers in developing countries are faced with challenges owing to their limited information on aquaculture management. Nile tilapia farmers in Teso North Sub-County recorded lower yields than expected in 2009 despite having been provided with required inputs. Water quality was suspected to be the key factor responsible for the low yields. This study sought to assess the effects of earthen pond water physico-chemical parameters on the growth of Nile tilapia in six earthen fish ponds under semi-intensive culture system in Teso North Sub-County. The study was longitudinal in nature with pond water and fish being the units of analysis. Systematic sampling was used to select five ponds while a control pond was purposively selected based on its previously high harvest. Four ponds were fed by surface flow and two by underground water. Each pond was fertilized and stocked with 900 fry of averagely 1.4 g and 4.4 cm. Physico-chemical parameters were measured in-situ using a multi-parameter probe. Sixty fish samples were randomly obtained from each pond fortnightly for four months using a 10 mm mesh size and measured, weighed and returned into the pond. Mean range of physico-chemical parameters were: dissolved oxygen (DO) 4.86-10.53 mg/l, temperature $24-26^{\circ}C$, pH 6.1-8.3, conductivity $35-87{\mu}S/cm$ and ammonia 0.01-0.3 mg/l. Temperature (p = 0.012) and conductivity (p = 0.0001) levels varied significantly between ponds. Overall Specific Growth Rate ranged between 1.8% (0.1692 g/day) and 3.8% (1.9 g/day). Ammonia, DO and pH in the ponds were within the optimal levels for growth of tilapia, while temperature and conductivity were below optimal levels. As temperature and DO increased, growth rate of tilapia increased. However, increase in conductivity, pH and ammonia decreased fish growth rate. Temperature and DO ranging between 27 and $30^{\circ}C$ and 5-23 mg/l, respectively, and SGR of 3.8%/day and above are recommended for higher productivity.

• 한국양식학회지
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• 제12권4호
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• pp.323-331
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• 1999

Most of channel fish farming in Alabama are still earthen pond style, and filled by rainfall and runoff. The water levels of ponds are maintained with stand-pipe, and the effluent from ponds very little discharged at usual time except ant heavy rains and crop season. Overflow from ponds following rains occurs mostly in winter and early spring when stream flows high. In this study to know how much effluents fish ponds affected to streams which are nearby ponds, a survey carried out on the variation of water quality of seven streams and effluents at heavy rains. Water samples were collected at 14 sites on upstream (did not affected by effluents) and downstream(being affect by effluents), and sampled monthly from August 1997 to August 1998. There were no clear trends of difference in most water quality variables between upstream and downstream of catfish farms during a year. The effluents from ponds after heavy rains were not highly polluted, but sometimes have elevated concentrations of TSS. Nitrogen content of effluents was higher than that of routine streams , but phosphorus was not clear. From this result suggest than the effluents from catfish farm are not having adverse impacts on stream water quality still yet .

• Toxicological Research
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• 제33권2호
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• pp.119-124
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• 2017

Hexavalent chromium is a bio accumulative toxic metal in water and fish. It enters aquaculture ponds mainly through anthropogenic sources. Hexavalent chromium concentrations and its effects on the morphology and behavior of Clarias gariepinus were investigated from four aquaculture ponds for 12 weeks. Chromium was measured using diphenyl carbohdrazide method; alkalinity and hardness were measured using colometric method and analyzed with Bench Photometer. Temperature and pH were measured using pH/EC/TDS/Temp combined tester. Temporal and spatial replications of samples were done with triplicates morphological and behavioural effects of the metal on fish were observed visually. Chromium ranged from no detection to 0.05 mg/L, alkalinity 105 to 245 mg/L, hardness 80 to 165 mg/L, pH 6.35 to 8.03 and temperature 29.1 to $35.9^{\circ}C$. Trend in the chromium concentrations in the ponds is natural > earthen > concrete > collapsible. There was a significant difference (P < 0.05) in chromium, alkalinity, water hardness, pH and temperature among the four ponds. Significant positive correlation also existed between alkalinity, water hardness, pH, with chromium. Morphological and behavioural changes observed in the fish include irregular swimming, frequent coming to the surface, dark body colouration, mucous secretion on the body, erosion of gill epithelium, fin disintegration, abdominal distension and lethargy. High chromium concentration in natural pond was due to anthropogenic run-off of materials in to the pond. Acidic pH, low alkalinity, low water hardness also contributed to the high chromium concentration. Morphological and behavioural changes observed were attributed to the high concentrations, toxicity and bio accumulative effect of the metal. Toxicity of chromium to fish in aquaculture could threaten food security. Watershed best management practices and remediation could be adopted to reduce the effects of toxicity of chromium on pond water quality, fish flesh quality and fish welfare.

• 한국해양바이오학회지
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• 제3권1호
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• pp.18-23
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• 2008

Fisheries constitute an important sector in national economic development, and estimate to contribute about 3% of the total GDP and 5% of the GDP in agriculture. Fish production from aquaculture has been estimated at 950 tonnes for 2004. In 2003, Ghana produced only 51.7% of its requirements from its domestic sources and in 2004, achieved 68.1% of its fish requirement through domestic production and imports. It has been estimated that the production from ponds and culture-based fisheries is worth about US$ 1.5 million a year. The aquaculture sub sector comprises largely small-scale subsistence farmers who practice extensive aquaculture in earthen ponds in contrast to the intensive practices of commercial farmers. There is one cage facility which produces 200 tonnes or 21.1% of the total output. There are several laws to regulate and govern the sector and the government has set up institutions that are responsible for developing fisheries and aquaculture policy and directing and establishing research priorities. The Directorate of Fisheries (DoF) is the lead government agency for aquaculture development and the Water Research Institute of the Council for Scientific and Industrial Research (CSIR) is mandated to carry out aquaculture research. To promote fish farming, imports of farm fish are not allowed.

• Fisheries and Aquatic Sciences
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• 제17권1호
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• pp.1-11
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• 2014

The Kenyan aquaculture sector is broadly categorized into freshwater aquaculture and mariculture. Whereas freshwater aquaculture has recorded significant progress over the last decade, the mariculture sector has yet to be fully exploited. The Kenyan aquaculture industry has seen slow growth for decades until recently, when the government-funded Economic Stimulus Program increased fish farming nationwide. Thus far, the program has facilitated the alleviation of poverty, spurred regional development, and led to increased commercial thinking among Kenyan fish farmers. Indeed, national aquaculture production grew from 1,000 MT/y in 2000 (equivalent to 1% of national fish production) to 12,000 MT/y, representing 7% of the national harvest, in 2010. The production is projected to hit 20,000 MT/y, representing 10% of total production and valued at USD 22.5 million over the next 5 years. The dominant aquaculture systems in Kenya include earthen and lined ponds, dams, and tanks distributed across the country. The most commonly farmed fish species are Nile tilapia Oreochromis niloticus, which accounts for about 75% of production, followed by African catfish Clarias gariepinus, which contributes about 21% of aquaculture production. Other species include common carp Cyprinus carpio, rainbow trout Oncorhynchus mykiss, koi carp Cyprinus carpio carpio, and goldfish Carassius auratus. Recently, Kenyan researchers have begun culturing native fish species such as Labeo victorianus and Labeo cylindricus at the National Aquaculture Research Development and Training Centre in Sagana. Apart from limited knowledge of modern aquaculture technology, the Kenyan aquaculture sector still suffers from an inadequate supply of certified quality seed fish and feed, incomprehensive aquaculture policy, and low funding for research. Glaring opportunities in the Kenyan aquaculture industry include the production of live fish food, e.g., Artemia, daphnia and rotifers, marine fish and shellfish larviculture; seaweed farming; cage culture; integrated fish farming; culture of indigenous fish species; and investment in the fish feed industry.

• Fisheries and Aquatic Sciences
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• 제22권9호
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• pp.20.1-20.8
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• 2019

Background: Despite the favorable geo-climatic potential of Cameroon, the national production of tilapia remains low due to poor tilapia growth reported by fish farmers. One of the underlying reasons is the early female maturation at a very small size and precocious breeding in earthen ponds, resulting in overpopulation which leads to stunted growth and therefore to the production of unmarketable fish size. Studies have shown that dietary supplementation of G. kola enhanced growth in young Clarias gariepinus and Oreochromis niloticus. It was also reported that G. kola inhibited spawning in Tilapia adult females. Therefore, this study sought to assess the effects of Garcinia kola as growth promoter and inhibitor of gonadal development in young Oreochromis niloticus. Methods: A total of 108 juveniles weighing $13.32{\pm}0.62g$ were randomly distributed in 9 hapas of 12 fishes each (9 females and 3 males) and fed for 70 days with three isonitrogenous diets, 40% crude protein with increasing Garcinia kola supplementation levels of 0 (normal diet), 6% and 10% (experimental diets). Physico-chemical parameters of the water (temperature, dissolved oxygen, pH, nitrate, nitrite, ammonia, and transparency) were measured twice a week. Every 14 days, fish were harvested, counted, and weighed. At the end of the experiment, three fish of each sex per replicate were sacrificed and their gonad and liver collected and weighed. Data were statistically analyzed using one-way analysis of variance repeated measure followed by Newman-Keuls multiple tests. Results: The results showed that all physico-chemical parameters of the water were within the recommended values for Tilapia culture. Tilapia fed 6% Garcinia kola supplemented diet displayed higher final body weight in males ($38.60{\pm}3.50g$) and females ($36.77{\pm}3.62g$) compared to those receiving normal diet ($36.23{\pm}1.36g$ and $25.87{\pm}3.32g$; respectively to the final body weight in males and females). The gonadosomatic index and hepatosomatic index indicated no significant variation in males while in females, these were significantly low in the experimental fish compared to control fish. Conclusion: The results of this study demonstrated that supplementation of G. kola seeds in diets of young Tilapia improved growth performance and impaired gonadal development in females.

• 한국양식학회지
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• 제20권4호
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• pp.278-288
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• 2007

새우양식은 90년대 서해안을 중심으로 빠르게 발달하여 2001년에는 2,605ha의 면적에서 3,268톤이 생산되었으나 2004년에는 2,368톤으로 해마다 감소되고 있다. 이러한 원인 중의 하나는 흰반점바이러스(WSSV)에 의한 대량폐사에 기인하는 것으로 알려져 있다. 흰반점바이러스는 현재 세계적으로 새우양식산업에 심각한 피해를 입히는 바이러스로 우리나라에는 1993년 처음 보고된 후 해마다 새우양식장에 반복적인 대량폐사를 유발시킨다. 축제식 새우양식장의 질병 피해를 감소시키기 위한 방법의 하나로서 새우와 어류, 패류, 해조류를 함께 복합양식하는 방법이 많은 연구되어 있으며 또한 육식성 어류와의 복합양식은 질병새우를 선택적으로 포식함으로써 새우의 바이러스 발병을 지연 혹은 억제시키는 것으로 알려져 있다. 새우양식장에 육식성 어류인 황복 Takifugu obscurus을 복합적으로 사육함으로써 바이러스 억제 효과를 조사하기 위하여 수면적 $1,616{\sim}1,848\;m^2$의 4개 축제식 양식장에 각각 흰다리새우($46.9/m^2$), 흰다리새우($43.4/m^2$)+황복($0.22/m^2$), 대하($24.6/m^2$), 대하($30.3/m^2$)+황복($0.25/m^2$)의 밀도로 입식하고 95일간 사육하였다. 대하 단독구와 복합구는 각각 51일, 57일째 WSSV 발병으로 전량 폐사하였다. 흰다리새우 단독구의 생존율은 18.2%인 반면 복합구의 생존율은 32.4%이며 단위생산량은 단독구에 비해 69.2%가 높아 흰다리새우는 황복과 복합양식이 단독양식에 비해 훨씬 유리한 것으로 나타났다. 사육수의 영양염(TAN, $NO_2-N,\;NO_3-N$) 농도는 복합구가 단독구에 비해 2배 이상 높았으나 전체적으로 새우의 성장에 적정범위를 유지하였다. 대하는 흰다리새우에 비해 WSSV에 대한 감수성이 높은 것으로 나타났으며 따라서 대하와의 복합양식은 이러한 점이 충분히 고려되어야 할 것이다.

• Fisheries and Aquatic Sciences
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• 제11권1호
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• pp.23-31
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• 2008

An experiment was conducted in twelve 0.02-ha rain-fed earthen ponds for 18 weeks to evaluate the effects of including pangasiid catfish (Pangasius hypophthalmus) in polycultures of major Indian carps, catla (Catla catla), rohu (Labeo rohita), and mrigal (Cirrhinus cirrhosus), on yield and economic gain. Treatment 1 ($T_1$) consisted of 5,000 catla+2,500 rohu+2,500 mrigal per ha, treatment 2 ($T_2$) consisted of 5,000 catla+2,500 rohu+2,500 mrigal+2,500 pangasiid catfish per ha, treatment 3 ($T_3$) consisted of 5,000 catla+2,500 rohu+2,500 mrigal+5,000 pangasiid catfish per ha, and treatment 4 ($T_4$) consisted of 5,000 catla+2,500 rohu+2,500 mrigal+7,500 pangasiid catfish per ha. The growth performance of fishes was evaluated by calculating specific growth rate, daily weight gain, and percent weight gain. Inclusion of pangasiid catfish in the carp polyculture resulted in significant increases in the growth and yield of catla and rohu. Catla and rohu grew most in $T_4$, with 7,500/ha of pangasiid catfish. The presence of pangasiid catfish did not influence the growth of mrigal. The growth of pangasiid catfish varied with stocking density, and they grew best at 5,000/ha ($T_3$). The carp and the combined fish yields were significantly higher in the carp polycultures with pangasiid catfish than with carps alone. The total carp and the combined fish yields were highest in $T_4$, in which the density of pangasiid catfish was greatest. However, the total carp and the combined fish yields in $T_3$ and $T_4$ were not significantly different. Profit differed significantly among treatments. Economic gain was highest in $T_3$, with 5,000/ha of pangasiid catfish, and lowest in $T_1$. The inclusion of pangasiid catfish in major carp polycultures results in higher fish yields and greater economic gain.

• 한국수산과학회지
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• 제9권4호
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• pp.261-263
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• 1976

1. 한국에서 처음으로 1975년 차넬메기의 종묘생산을 위해 지중산란을 시도하였으나 실패하였고 1976년 다시 지중산란을 시도하고, 또 Pen cage식 산란을 시도하면서 뇌하수체 hormone 주사도 하였으나 산란하지 않았다. 그러나, 전시용으로 수조에 둔 암컷 4마리, 수컷 1마리중 1쌍이 1976년 7월 산란하였다. 2. 산란한 수조의 조건은 실내에서 순환여과식사육제치로 pH는 $7.2\~7.4 $의 범위로 치유되었고 수온변화는 Table 2에 나타난 바와 같이 순간 평균 $19.3^{\circ}C$에 $23.6^{\circ}C$까지 서서히 변화하였다. 3. 산란에 실패한 지중에 처음 주입된 물은 지하수로서 실내의 전시용 수조에 사용된 물과 같은 수원의 물이며, 수온은 75년에는 순간 평균 $17.2\~29.8^{\circ}C$의 범위였고 76년에는 $19.7\~28.4^{\circ}C$로 산란에 적당한 범위내라고 인정되었으나 pH는 조류 및 수조의 광합성의 영향으로 $7.3\~9.5$의 범위로 변화가 심하였다. 이는 Nelson이 pH $8.5\~10.0$ 범위의 사육수에서 산란에 실패한 결과와 더불어 높은 pH는 차넬메기의 산란을 제어하는 요인으로 인정된다.

• 생명과학회지
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• 제18권9호
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• pp.1186-1193
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• 2008

방글라데시 미멘싱에 소재하는 양식어장에서 pangasiid catfish (Pangasius hypophthalmus), silver carp (Hypophthalmichthys molitrix)와 catla (Catla catla)의 조합과 혼합비를 달리하여 16주간 복합양식하였을 때, 이들 어종의 성장률을 조사하였다. 헥타르당 30,000개체의 밀도로 복합양식하여 성장률을 측정하였으며, 혼합조성비는 다음과 같다: 실험구(treatment) 1은 pangasiid catfish와 silver carp을 1:1비율로, 실험구 2는 pangasiid catfish와 cata를 1:1비율로, 실험구 3과 4는 pangasiid catfish, silver carp과 catla를 각각 2:1:1과 3:2:1비율로 복합양식하였다. 양식환경에 영향을 주는 수온, 투명도, 용존산소량, pH, $NO_{3}-N$, $PO_{4}-P$, 엽록소 a와 같은 몇몇 물리화학적, 생물학적 요인과 플랑크톤의 군집을 정기적으로 조사하였다. 어류의 성장속도는 비 성장율(specific growth rate), 일간 체중 증가(daily weight gain)와 체중증가 비율(percent weight gain)을 측정하였다. Pangasiid catfish의 성장률과 사료이용률은 모든 실험구에서 유사하게 나타났다. Silver carp의 성장률은 모든 실험구에서 유의한 차이를 나타내었는데(p<0.05), 양식밀도가 증가할수록 성장률이 현저하게 감소하였으며, Silver carp의 밀도가 가장 낮은 복합양식 조성인 pangasiid catfish, silver carp과 catla의 비율이 각각 2:1:1일 때, silver carp의 성장률이 가장 높게 나타났다. Silver carp의 밀도가 증가할수록 catla의 성장률이 현저하게 감소하는 것으로 나타나, catla의 성장률은 silver carp의 유무에 영향을 받는 것으로 판단되었다. Catla의 성장률은 pangasiid catfish와 calta의 비율이 1:1일 때, 가장 높은 것으로 나타났다. 양식수율과 경제적 이익은 실험구에 따라 현저하게 다른 양상을 보였다(p<0.05). 가장 높은 양식수율과 경제적 이익은 pangasiid catfish, silver carp과 catla를 각각 2:1:1 비율로 양식한 결과에서 얻어졌는데, 이는 silver carp의 높은 성장률과 catla의 시장 단가가 높은 것에 기인하는 것으로 나타났다. 모든 실험구의 수질 상태는 양식기간 동안 적절한 수준을 유지하였으며, 각각의 값은 모든 실험구에서 뚜렷한 차이를 보이지 않았다(p<0.05).