“集约型”池塘养鱼试验效果与分析

在池塘中央采用高密度、全人工投饵技术方法单养名优鱼类，入池规格及密度为单雄性罗非鱼（全长３～４ｃｍ）６４００尾／亩，斑点叉尾ｈｕｉ（平均尾重５０ｇ）２４００尾／亩，湘云鲫（全长３～４ｃｍ）８０００尾／亩；经１５０～１９０天饲养，平均亩产１３０７～１５２７ｋｇ，饲料系数１．５～１．８，亩产值１．２２～２．０９万元，亩利锐２２４０～５３７４元。“集约型”池塘养殖的单位水面产出能力显著高于以“肥水”养殖     

池塘主养斑点叉尾Hui大规格鱼种高产试验

在面积为1．5亩的池塘内主养斑点叉尾Hui鱼种，搭配美国大口胭脂鱼、花白链。试验采用人工驯化、投喂全价配合颗粒饲料、适时调节水质等方法。经过约150天饲养，总产鱼1134．3kg，平均亩产鱼756．2kg，其中斑点叉尾Hui总产664．5kg，平均亩产443kg，平均规格161．8g/尾。平均亩利润4901．3元，投入产出比为1：1．8。     

斑点叉尾鮰养殖试验

研究了美国斑点叉尾生物学特性、盐碱地池塘养殖、饵料配制、与家鱼混养等技术。在２０亩池塘中，平均亩产成鱼５０５．８ｋｇ，其中烟３５７．６ｋｇ，平均规格０．４４ｋｇ／尾，平均增长６０倍以上，每亩纯利３０３４．了６元。１９９４年专家鉴定认为，产量、效益、增长速度均达省内先进水平。     

斑点叉尾Hui养殖试验

研究了美国斑点叉尾Ｈｕｉ生物学特性、盐碱地池塘养殖、饵料配制、与家鱼混养等技术，在２０亩池塘中，平均亩产成鱼５０５．８ｋｇ，其中Ｈｕｉ３５６．６ｋｇ，平均规格０．４４ｋｇ／尾，平均增长６０倍以上，每亩纯利３０３４．７６元，１９９４年专家鉴定认为，产量、效益、增长速度均达省内先进水平。     

池塘主养彭泽鲫技术

彭泽鲫是农业部重点推广的淡水良种之一，具有食性广、生长迅速、抗病力强、容易繁殖、个体大、起捕率高、营养价值高等优良性状，是调整淡水养殖品种结构的重要品种之一。近几年来，在我省养殖推广过程中涌现出一些成功典型，取得了显著的经济效益和社会效益。例如章丘市水产站承包１口６亩池塘，主养彭泽鲫成鱼，４月２日放养彭泽鲫鱼种３１４．５ ｋｇ，１０ ６３９尾，６月 ８日套养鲢鳙乌仔 １．５万尾，１０月底收获，总产鱼３ ４２６．８ ｋｇ，其中彭泽鲫２ ４７６．８ ｋｇ，链鳙鱼 ９５０ ｋｇ，平均亩产彭泽鲫 ４１２．８ｋｇ，…     

斑点叉尾Hui大规格鱼种培育技术初报

在面积０．６７ｈｍ＾２，水深１．５ｍ的池塘中投放体长为３ｃｍ的斑点叉尾Ｈｕｉ鱼苗９万尾，用干红虫饲养１８８ｄ，共产大规格斑点叉尾Ｈｕｉ鱼种１ １７４ｋｇ，平均规格６２尾／ｋｇ，养殖成活率８７．５％，每６６７ｍ＾２获利３ ７８０元，投入产出比为１：１．８７。     

涝洼地养殖罗氏沼虾试验

在水库区和河滩涝洼地挖池试养罗氏沼虾,１９９６年试养８亩,１９９７年试养１０亩。采取清池肥水,池底设隐蔽物,投喂人工配饵,调控水质等措施,１９９６年共产罗氏沼虾４００ｋｇ,平均亩产５０ｋｇ,平均体长８．０ｃｍ,尾重１７．５ｇ,成活率３０．５％,饵料系数３．５：１９９７年共产虾５２５ｋｇ,平均亩产７５ｋｇ,平均体长８．５ｃｍ,尾重２０ｇ,存活率３５％饵料系数２．５。投入产出比分别为１：２．１和１：２     

池塘主养斑点叉尾试验小结

斑点叉尾具有食性杂、生长快、群体产量高、适应性强、易饲养等优点。１９９９年 ,我市水产部门在国家农业综合开发区示范村—民安镇才旺村进行了养殖试验 ,并取得了成功。４月１０日投放鱼种 ,１１月２０日测产验收三口试验池共１．２ｈｍ２ ,总产鱼９２２４ｋｇ ,其中斑点叉尾７３４０ｋｇ ,平均规格０．６５ｋｇ／尾 ,鲢鱼１０１０ｋｇ,平均规格０．６１ｋｇ／尾 ,鳙鱼８７４ｋｇ,平均规格０．５４ｋｇ／尾。试验池每６６７ｍ２产值８６７８元 ,纯利４７３３元 ,投入产出比１∶２．２。１池塘条件试验面积分别为０．２７ｈｍ２、０．…     

虾池综合利用技术

在１０３６亩试验池中，进行虾贝、虾鱼混养，共收获对虾６６３６２ｋｇ，平均亩产６４ｋｇ，混养海湾扇贝５１０亩，收获６１２００ｋｇ，平均亩产１２０ｋｇ；混养牡蛎４０６亩，收获６０９ｔ，平均亩产１．５ｔ，混养梭鱼１２０亩，收获７２００ｋｇ，平均亩产６０ｋｇ。     

小型水库养鱼技术开发试验

对１０３座小型水库养高产技术进行了开发试验，１９９１年试验１０８５７亩，总产鱼１９０９．８Ｔ，平均亩产１７５．９ｋｇ每亩勇利３３５．４元，１ｋｇ盈利１．９１元；投入产出比１：２．０８。专家鉴定认为，本试验的面积产量均达到国内先进水平。     

Evaluation of Various Concentrations of Dietary Protein and Animal Protein for Pond-Raised Channel Catfish Ictalurus punctatus Fed to Satiation or at a Restricted Rate

A factorial experiment was conducted to evaluate effect of dietary protein (28% or 32%), animal protein (0, 3, or 6%), and feeding rate (satiation or >90 kg/ha per d) on production characteristics, processing yield, and body composition of pond-raised channel catfish Ictalurus punctatus . Fingerling channel catfish (average weight: 55 g/fish) were stocked into 60, 0.04-ha ponds at a rate of 18,530 fish/ha. Five ponds were used for each dietary treatment. Fish were fed once daily to satiation or no more than 90 kg/ha per d for 147 d. Fish fed at a rate of >90 kg/ha per d consumed about 85% of the amount of feed consumed by fish fed to satiation. Dietary protein did not affect the total amount of feed fed, amount of feed consumed per fish, weight gain, feed conversion efficiency, or fillet protein. Animal protein had no effect on the total amount of feed fed, amount of feed consumed per fish, weight gain, or fillet protein and ash. Fish fed a diet containing 6% animal protein converted feed more efficiently than fish fed diets containing 0% and 3% animal protein. Fish fed to satiation daily consumed more feed, gained more weight, converted the feed less efficiently, and had a higher carcass yield, a higher level of visceral fat as compared to fish fed at a rate of >90 kg/ha per d. Feeding rate had no effect on fillet protein. Results from this study indicated that both a 28% and a 32% protein diet with or without animal protein provided the same growth rate of channel catfish raised in ponds from fingerlings to marketable size if feed is not restricted below a maximum rate of 90 kg/ha per d. Even though there were some interactions among the three factors evaluated, dietary protein levels of 28% to 32% and animal protein levels of 0% to 6% do not appear to markedly affect carcass yield and fillet proximate composition of pond-raised channel catfish.     

盐碱荒滩池塘大面积套养梭鱼试验

在3055亩盐碱荒滩池塘中进行了大面积套养梭鱼试验。亩均放养大规格鱼种643尾，其中梭鱼占总放养量的24％。清塘施肥，科学投饵，调节水质，防治鱼病，经8个月的饲养管理，亩均产商品鱼424．2kg,其中梭鱼109.3kg，亩均纯利润1229.1元，投入产出比1：1．5，该成果达到国内先进水平。     

Costs and Risk of Catfish Split‐pond Systems

Split ponds are recently developed pond‐based aquaculture systems that allow intensification of catfish aquaculture. Successful industry‐wide adoption of newly developing technologies like split‐pond systems will depend upon their productivity and cost efficiencies. Costs and production performance of the following three split‐pond design scenarios were monitored in Arkansas and Mississippi: (1) research design developed at the Thad Cochran National Warmwater Aquaculture Center, Stoneville, Mississippi; (2) waterwheel design tested on commercial catfish ponds; and (3) screw‐pump design tested on commercial catfish ponds. An economic engineering approach using standard enterprise budget analysis was used to develop estimates of breakeven prices (BEPs) ($/kg) for producing foodsize hybrid catfish (♂Ictalurus furcatus × ♀Ictalurus punctatus) for each scenario. Estimates of BEPs of hybrid catfish raised in split ponds ranged from $1.72 to $2.05/kg. The cost of catfish production in split ponds was sensitive to yield, fish prices, and feed prices. Annual net cash flows from both commercial split‐pond systems were high and sufficient to make the investment profitable in the long run. Feed price, feed conversion ratio, and yield contributed the most to downside risk of split ponds.     

Effects of Dietary Protein Level and Feeding Regimen on Growth and on Fattiness of Channel Catfish,Ictalurus punctatus

Two studies were conducted to evaluate the effects of (I) high-protein (38%) finisher feed fed to satiation for 30,45,60, or 90 days prior to harvest and (2) dietary protein (32 vs. 38%) and feeding regimen (satiation or restricted) on growth and fattiness of channel catfish. Each study was conducted for two years in earthen ponds stocked with channel catfish at a rate of 13,590 fish/ha (35 to 40 g initial weight) for year 1 and 6,800 fish/ha (0.45 to 0.6 kg initial weight) for year 2. Years refer to year of experiment and not fish age class. There were no significant differences in total yield, dressed yield, or muscle fat, regardless of diet or feeding regimen within year. Year-one fish (study 2) fed to satiation tended to gain more weight and appeared to convert feed better than fish fed at a restricted rate. In study 2 there were significant interactions between year and feed, and between year and feeding regimen. Percentage visceral fat was reduced by feeding a high-protein feed during year 1 (study 1). Females also generally had a higher percentage visceral fat than males, regardless of diet. Year-two-fish generally contained a higher percentage of visceral fat as compared to year-one fish. In study 2, there was a significant interaction effect between year, feed, feeding regimen, and sex on visceral fat. Increasing dietary protein or restricting feed appeared to have only marginal effects on fattiness in channel catfish. Fish size and/or age appeared to influence fattiness more than diet or feeding regimen.     

Influence of forage fish and dietary lipid supplements on egg quality and fry production in channel catfish (Ictalurus punctatus) × blue catfish (Ictalurus furcatus) hybridization

Hybrid catfish (channel catfish Ictalurus punctatus × blue catfish Ictalurus furcatus) display characteristics that are favourable to aquaculture production. Low hatch percentages are a principal reason this hybrid is not used widely in the catfish industry. This study was conducted to determine whether additional food source rich in lipids may lead to a higher quality egg production. A 10‐week feed trial was conducted in ponds in Auburn, AL. A total of 219 female Kansas Select channel catfish were stocked into nine ponds, 0.04 ha in size. Three dietary treatments were randomly allocated to the ponds. Diet‐1 was a standard 60 g kg^?1 lipid floating catfish feed. Diet‐2 was the same feed supplemented with forage fish at ～28 kg ha^?1. The third diet was the aforementioned catfish feed topcoated with 20 g kg^?1 lipid [10 g kg^?1 menhaden fish oil, 5 g kg^?1 high docosahexaenoic acid (DHA) oil and 5 g kg^?1 high arachidonic acid oil]. Results indicate that brood fish fed the high lipid diet spawned larger egg masses and had larger eggs both in weight and in diameter, with increased complements of fatty acids such as DHA, eicosapentaenoic acid and total n‐3 fatty acids. The neutral and polar lipid fractions are also presented.     

Effects of Periodic Feed Deprivation on Growth, Feed Efficiency, Processing Yield, and Body Composition of Channel Catfish Ictalurus punctatus

Two studies were conducted in 110‐L flow‐through aquaria and 0.4‐ha ponds to evaluate effects of periodic feed deprivation on the growth performance of channel catfish Ictalurus punctatus. Fish were deprived of feed 0, 1, 2, or 3 consecutive d/wk, l d per 5‐d period, or 3 consecutive d per 10‐d period and fed to satiation on days fish were fed. In Experiment 1, fish fed less frequently than daily consumed significantly less feed (over the experimental period) and gained significantly less weight than fish fed daily, except that feed consumption of fish deprived of feed 1 d/wk was not significantly different from that of fish fed daily. Compared with fish fed daily, fish deprived of feed 2 d/wk had significantly lower feed conversion ratio (FCR). Visceral fat of fish deprived of feed 1 or 2 d/wk was similar to that of fish fed daily, but fish deprived of feed for longer periods had significantly lower visceral fat than fish fed daily. Regression analysis indicated that feed consumption, weight gain, and visceral fat increased linearly as the number of days that fish were fed increased. In Experiment 2, there were no significant differences in the amount of feed fed between fish deprived of feed 1 d/wk and those fed daily. Net production of fish deprived of feed 1 or 2 d/wk or 1 d per 5‐d period was not significantly different from that of fish fed daily, but fish deprived of feed for longer periods had significantly lower net production than fish fed daily. Visceral fat of fish deprived of feed 1 d/wk or 1 d per 5‐d period was similar to that of fish fed daily, but fish on other treatments had significantly lower visceral fat than fish fed daily. Regression analysis showed that as the number of days fed increased the amount of feed fed and net production increased quadratically. Feed conversion ratio, carcass yield, visceral fat, and fillet fat increased, while fillet moisture decreased linearly as the number of days fed increased. Although feeding less frequently than daily may improve feed efficiency, and fish deprived of feed may demonstrate compensatory growth when a full feeding regime is resumed, it may be difficult to provide enough feed to satiate all size‐classes of fish under a multiple‐batch cropping system without causing water quality problems. Under normal economic conditions, fish should be fed daily to apparent satiation without waste and without causing water quality problems. However, during periods of unfavorable economic conditions, channel catfish raised from advanced fingerlings to market size may be fed less frequently than daily to reduce production cost. Results from the present study indicated that feeding channel catfish to satiation 5 or 6 d/wk (not feeding on one or two weekend days) could provide some benefits in reducing production cost through reduced feed and labor costs for food‐sized channel catfish during periods of low fish prices and high feed prices.     

Economics of Intensively Aerated Catfish Ponds

The US catfish industry is evolving by adopting production‐intensifying practices that enhance productivity. Catfish producers have increased aeration rates over time, and some now use intensive rates of aeration (>9.33 kW/ha). Costs and production performance were monitored at commercial catfish farms using high levels of aeration (11.2–18.7 kW/ha) in Alabama, Arkansas, and Mississippi. A multivariate‐cluster analysis was used to identify four different management clusters of intensively aerated commercial catfish farms based on stocking density, size of fingerlings at stocking, and feed conversion ratios (FCR). Breakeven prices of hybrid catfish raised in intensively aerated pond systems were estimated to range from $1.86/kg to $2.17/kg, with the lowest costs associated with the second greatest level of production intensity. The two medium‐intensity clusters generated sufficiently high revenues for long‐term profitability. However, the least‐intensive and the most‐intensive clusters were economically feasible only when catfish and feed prices were closer to less probable market prices. Feed price, FCR, and yield contributed the most to downside risk. Intensive aeration in catfish ponds, up to the levels analyzed in this study, appears to be economically feasible under the medium‐intensity management strategies identified in this analysis.     

Growth of Stocker Channel Catfish to Large Market Size in Single-Batch Culture

Catfish farmers increasingly are producing fish larger than the traditional size of 0.45-0.57 kg/fish in order to meet processing plant requirements for larger fish. Production of larger channel catfish Ictalurus punctatus in multiple-batch culture has been investigated in a few studies, but the impact of understocked fingerlings on growth of carry-over fish is unknown. The present study was conducted to quantify growth, feed conversion ratio, net daily yield, and net and total yield of stocker channel catfish grown in single-batch, one-season culture to mean individual weights of 0.60, 0.72, 0.91, or 1.17 kg/fish. Channel catfish (mean weight = 0.26 kg/fish) were stocked into 12 0.1-ha ponds at 11,115 fish/ha. Fish were fed a 32% crude protein floating extruded feed once daily to apparent satiation. When the average weight of the fish population reached the target weight, three randomly selected ponds were harvested. Fish growth was linear in all treatments. Growth rates were similar for fish grown to 0.60, 0.72, and 0.91 kg/fish, and significantly lower ( P < 0.05) than for fish grown to 1.17 kg. Variation in individual fish weight increased linearly with increased duration of culture period. Feed conversion ratio averaged 1.9 and did not differ significantly among treatments. The percentage of the fish population at harvest that fell within the 0.57 to 2.04 kg-size range preferred by processing plants increased from 56.6 to 98-5% as the mean weight at harvest increased from 0.60 to 1.17 kg/fish.     

Comparative growth and yield of channel catfish and channel × blue hybrid catfish fed a full or restricted ration

Growth and yield (kg ha^?1) of the channel catfish (Ictalurus punctatus, Rafinesque, 1818) and the channel × blue hybrid catfish [I. punctatus female ×I. furcatus (Lesueur, 1840) male], which shared the Jubilee strain of channel catfish as the maternal parent, were compared in sixteen 0.1 ha earthen ponds (14 852 fish ha^?1) during the April to November growing season. Each fish genetic group was fed a commercially formulated 32% protein feed daily to apparent satiation or at 80% of the mean daily satiation ration. Net yield and individual weight were higher for channel × blue hybrid catfish compared with channel catfish and for fish fed a full ration compared with a restricted ration. When fed a full ration, the channel × blue hybrid catfish grew faster from May to September than did the purebred channel catfish because the hybrid catfish consumed a greater percentage of its body weight at each feeding. Net yield within each fish genetic group was lower when feed ration was restricted. The per cent reduction in net yield in response to feed restriction was similar for each fish genetic group.