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Pampanga is the top tilapia-producing province in Philippines. One of its municipalities, Minalin, is considered as one of its major centers of production. This study aims to determine the impacts of climate change hazards on the ...
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Pampanga is the top tilapia-producing province in Philippines. One of its municipalities, Minalin, is considered as one of its major centers of production. This study aims to determine the impacts of climate change hazards on the economic performance of tilapia-intensive pond culture in Minalin, Pampanga considering the threats to the industry, livelihoods, and food security. Results revealed that the economic performance of tilapia pond operations using semi-intensive large-scale culture was affected by climate change, as reflected in the reduction of yield among tilapia pond operators. This makes intensive tilapia pond farming in Minalin still a viable venture but will now require more than a year to pay for investment (variable and fixed) costs if under climate change risks. The study recommends strengthening capacity building related to climate-smart tilapia farming technologies for pond operators and to implement appropriate technologies to address climate change risks.
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Fish size and harvest density generally exhibit a negative relationship in pond culture, but the influence that pond substrate type can have on this relationship is not well understood. To evaluate the influence of pond substrate ...
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Fish size and harvest density generally exhibit a negative relationship in pond culture, but the influence that pond substrate type can have on this relationship is not well understood. To evaluate the influence of pond substrate type on yellow perch (Perca flavescens), harvest density (number/hectare) was linearly regressed against individual fingerling size (grams) for lined (n = 48) and earthen (n = 40) substrate ponds that were treated similarly in terms of organic fertilizer use and the number of days in the pond over 12 culture seasons at Blue Dog Lake State Hatchery, South Dakota, USA. Harvest density explained 45 and 39% of the variation in yellow perch size in lined and earthen-substrate ponds (all P P = 0.62);however, fingerling size was significantly larger in lined ponds regardless of density that varied from near 0 to 700,000 per hectare (y-intercept comparison, P < 0.01). At the same harvest density, lined ponds will tend to produce larger yellow perch fingerlings compared to earthen ponds when similar organic fertilizers are used.
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Reduced walleye (Sander vitreus) fingerling production possibly related to nuisance filamentous green algae and overly stable water chemistry patterns is a concern in earthen-substrate ponds at Blue Dog State Fish Hatchery, South ...
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Reduced walleye (Sander vitreus) fingerling production possibly related to nuisance filamentous green algae and overly stable water chemistry patterns is a concern in earthen-substrate ponds at Blue Dog State Fish Hatchery, South Dakota, USA. We describe the success of alfalfa (Medicago sativa) meal (AFM, n=2), alfalfa meal plus soybean (Glycine max) meal (AFM+SBM, n=1), and alfalfa meal plus liquid 28N:0P:0K (AFM+28:0:0, n=1) at achieving walleye production objectives (>104,000 walleye and 32 kilograms/hectare) as well as the occurrence of filamentous green algae and the associated patterns of ammonia-nitrogen, pH, and dissolved oxygen in earthen-substrate ponds. Walleye production objectives were only achieved when filamentous green algae were absent preceding harvest, which occurred in one pond that received AFM and in the pond that received AFM+28:0:0.The presence of filamentous green algae preceding harvest was associated with higher dissolved oxygen and pH, whereas declines in these variables occurred when filamentous green algae were absent. Organic fertilizer alone exhibited low ammonia-nitrogen (<0.1 mg/L) despite the substitution of higher protein content soybean meal, but supplementation with 28:0:0 increased ammonia-nitrogen to 0.23 mg/L. These findings highlight the reduction in walleye fingerling production that occurred in the presence of filamentous green algae and the unpredictability of results when two earthen-substrate ponds are treated exactly the same with alfalfa meal. Achievement of walleye production objectives, lack of nuisance filamentous green algae, and promotion offavorable patterns in water chemistry warrant future experimentation with alfalfa meal supplemented with 28:0:0 in earthen-substrate ponds at this hatchery.
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Walleye (Sander vitreus) fingerling production can be enhanced when the pond substrate is altered from earthen soils to an exposed liner;however, few differences in water chemistry, prey densities, and food habits have been identi...
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Walleye (Sander vitreus) fingerling production can be enhanced when the pond substrate is altered from earthen soils to an exposed liner;however, few differences in water chemistry, prey densities, and food habits have been identified that could potentially explain this production difference. Lack of an explanation led to further comparison of walleye fingerling culture between substrate types during 2016. Two ponds of each type were stocked with 1- to 3-day-old walleye fry, but lined ponds received an additional 104,166 fry/ha and were stocked 1 or 2 days later than earthen ponds (May 10). Walleyes in lined ponds achieved a growth advantage on May 31 (+2.5 mm) and on June 6 (+3.3 mm), but lengths were not significantly different at harvest (June 15). Lined ponds increased walleye yield and number 1.8-fold while not reducing individual fish size at harvest compared to earthen ponds. Walleye food habits were generally similar between pond types with a greater number of zooplankton being consumed through June 6 followed by an increase in larval chironomid consumption at harvest (June 15). After May 30, lined ponds exhibited lower dissolved oxygen and higher ammonia-nitrogen concentrations even though earthen ponds received additional (157 kg/ha) alfalfa (Medicago sativa) meal fertilizer. Also, at this time pH declined abruptly and remained below 8.2 in lined ponds. Moreover, the enhanced production in lined ponds coincided with walleyes that exhibited an increased pelagic (δ13C) signature during the culture period (2‰ to 3.3‰ more negative). Efforts to improve production in earthen-substrate ponds should focus on increasing the pelagic signature of the food web through fertilization strategies which increase ammonia-nitrogen (≈0.3 mg/L) and decrease dissolved oxygen (≈6.5 mg/L) while maintaining a pH between 8.0 and 8.2 during the second half of the rearing interval.收起
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By using the methods of qualitative and quantitative analysis, the species composition and dominant genus of harmful, ciliates in young abalone culture ponds are studied. Totally 68 species of ciliates, belonging to 3 classes, 16 ...
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By using the methods of qualitative and quantitative analysis, the species composition and dominant genus of harmful, ciliates in young abalone culture ponds are studied. Totally 68 species of ciliates, belonging to 3 classes, 16 orders and 46 genus, are found. The dominant ciliate species are Aspidisca leptaspis, Vorticella sp. and Euplotes rariseta. During the young abalone cultivation, the numbers of young abalones increase first,and then show a trend of decreasing. The relationship between the density and composition of ciliates and the density of algae in the young abalone culture ponds is also discussed.
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Adjustments to rearing practices should be justified with increases in production, stocking success, or angler satisfaction. Largemouth bass (Micropterus salmoides) production was assessed between hatchery ponds where fish were re...
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Adjustments to rearing practices should be justified with increases in production, stocking success, or angler satisfaction. Largemouth bass (Micropterus salmoides) production was assessed between hatchery ponds where fish were restricted to an invertebrate diet or received supplemental fathead minnow (Pimephales promelas) forage during 2015. At harvest, age-0 bass yield was 4.5 times greater and average fish length was 38 mm longer, in the pond that received fathead minnow. In 2016, a second study evaluated the timing of minnow supplementation that included earlier stockings of small fathead minnow (<30 mm) compared to delayed supplementation with larger (>30 mm) minnows. With earlier supplementation, bass yield was 2.3 times greater and fish averaged 14 mm longer at harvest. Bass survival was approximately 38% higher during 2015 when supplementation occurred and 25% higher during 2016 when minnow supplementation began earlier. Our findings show invertebrate forage was probably limiting bass production in hatchery ponds and supplementing with appropriately-sized fathead minnows increased age-0, largemouth bass production.
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Chinese sea perch(Lateolabrax Maculatus)is one of the main marine fish culture species in China,its green development has received increasing attention and its ecological economic study is rare.Based on field survey,this paper tak...
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Chinese sea perch(Lateolabrax Maculatus)is one of the main marine fish culture species in China,its green development has received increasing attention and its ecological economic study is rare.Based on field survey,this paper takes water pollution tax of China as conversion indicator for aquaculture eutrophication to simulate aquaculture waste fee for further analyzing the ecological impact of Chinese sea perch’s aquaculture.For data analysis,data envelopment analysis model has been used.The comparison for Chinese sea perch’s economic performance and ecological economic performance under its main aquaculture systems has been done.The results show that:1.The simulated waste fee has no significant impact for the comparison.2.Ranking for ecological economic performance’s ecological economic,technical and scale efficiency is as follow:pond farming,offshore cage culture and cage culture.3.Offshore cage culture is the only system presenting positive increase for ecological economic performance,which makes its aquaculture activity more sustainable than other systems.4.The key point of green development is to maximize the ecological economic efficiency of main aquaculture systems.Thus,offshore cage culture is the most sustainable aquaculture system among China’s current marine fish culture systems,and other systems need innovation for achieving the green development of China’s aquaculture.
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