Effects of Fertilization and of Fry Stocking Density on Pond Production of Fingerling Walleye,Stizostedion vitreum

The influence of fertilization and of fry stocking density on production of fingering walleye, Stizostedion vitreum, was evaluated in earthen ponds at North Platte State Fish Hatchery, North Platte, Nebraska. In 1990, five 0.4-ha ponds were fertilized with alfalfa pellets, and five were fertilized with soybean meal; four unfertilized ponds served as controls. All ponds were stocked with D2 (Dl = the day at hatch) walleye fry at 250.000ha. Differences in yield, number of fingerlings harvested, mean length, and mean weight amone treatments were not statistically significant (P> 0.05). In 691, two fertilization schedules (no fertilizer and fertilization with alfalfa pellets) and two fry stocking rates (250.000 and 375,000 fry/ha) were evaluated. Four ponds were used for each treatment. Statistically significant treatment differences were found in yield, number of fingerlings harvested/ha, average length, and average weight. Yield was higher in fertilized ponds compared with yield from unfertilized ponds at both stocking densities, but yield did not differ significantly between stocking density treatments given the same fertilizer treatment. Survival did not differ between density treatments, but total number of fish harvested was significantly greater from ponds stocked at the higher density. Fingerlings with the largest average weight were raised in fertilized ponds that were stocked at 250,00O/ha, while the smallest fingerlings were from unfertilized ponds that were stocked at 375,000ka. Days in culture interval, which varied among ponds by 9 days in 1990 and 10 days in 1991, was significantly correlated with most production variables in 1990 and with all production variables in 1991. Means of water quality variables were not significantly different between fertilized and unfertilized ponds in either year, but significant differences were found in means of three water quality variables between 1990 and 1991. Yield in both fertilized and unfertilized ponds in 1991 was less than in 1990.     

Effects of simazine treatment on channel catfish and bluegill production in ponds

Application of 13.4 kg/ha of simazine to the bottom of channel catfish (Ictalurus punctatus) ponds before flooding resulted in an extended period of low dissolved oxygen, a 19% reduction (P < 0.01) in channel catfish yield, and poorer feed conversion by fish when compared to control ponds. A single application of 1.5 mg/l of simazine to the water of fertilized bluegill (Lepomis macrochirus) ponds also decreased dissolved oxygen. The 11% reduction in bluegill yield was not statistically significant (P > 0.05). Simazine treatment caused an initial reduction in macrophyte coverage in bluegill ponds, but macrophyte coverage increased as simazine concentrations in the pond water declined.     

Effects of manures and pelleted feeds on survival,growth, and yield of Penaeus stylirostris and Penaeus vannamei in Panama

Brackishwater ponds on the Pacific coast of Panama were stocked at 5/m² with wild-caught postlarval shrimp (0.05 g). Species composition at stocking was 56% Panaeus vannamei, 33% P. stylirostris and 11% P. occidentalis. Experimental treatments were: chicken manure (4500 kg/ha dry weight), cow manure (4500 kg/ha), 25% protein pelleted feed (790 kg/ha) and control (which received no nutrient input). Water was exchanged 5–10% daily throughout the 120-day production period during the 1982 rainy season. Average shrimp yields at harvest, by treatment, were: chicken manure, 262 kg/ha; cow manure, 218 kg/ha; feed, 386 kg/ha; and the control, 160 kg/ha. Average survival for each treatment was 50%, 76%, 58% and 77%, respectively. All P. occidentalis died during the production period. Survival was not significantly different among treatments (P > 0.05). Average weights or shrimp at harvest were 8.72g, 7.32 g, 12.07 g, and 5.98 g, respectively, for the treatments. Manures and feed significantly increased yield over the control (P < 0.002). Feed significantly increased yield over that of the manures (P < 0.0001), while yield for manures did not differ (P > 0.05). A partial budget analysis indicated that a net income for the feed treatment was higher than for chicken manure or cow manure treatments.     

Effects of Two Densities of Caged Monosex Nile Tilapia, Oreochromis niloticus, on Water Quality, Phytoplankton Populations, and Production When Polycultured with Macrobrachium rosenbergii in Temperate Ponds

The effects of different densities of caged Nile tilapia, Oreochromis niloticus, on water quality, phytoplankton populations, prawn, and total pond production were evaluated in freshwater prawn, Macrobrachium rosenbergii, production ponds. The experiment consisted of three treatments with three 0.04‐ha replicates each. All ponds were stocked with graded, nursed juvenile prawn (0.9 ± 0.6 g) at 69,000/ha. Control (CTL) ponds contained only prawns. Low‐density polyculture (LDP) ponds also contained two cages (1 m³; 100 fish/cage) of monosex male tilapia (115.6 ± 22 g), and high‐density polyculture (HDP) ponds had four cages. Total culture period was 106 d for tilapia and 114 d for prawn. Overall mean afternoon pH level was significantly lower (P ≤ 0.05) in polyculture ponds than in CTL ponds but did not differ (P > 0.05) between LDP and HDP. Phytoplankton biovolume was reduced in polyculture treatments. Tilapia in the LDP treatment had significantly higher (P ≤ 0.05) harvest weights than in the HDP treatment. Prawn weights were higher (P ≤ 0.05) in polyculture than prawn monoculture. These data indicate that a caged tilapia/freshwater prawn polyculture system may provide pH control while maximizing pond resources in temperate areas.     

Polyculture of the Giant Malaysian Prawn and the Golden Shiner in Southwestern Louisiana1

Juvenile prawns (Macrobrachium rosenbergii) were stocked at 37,050/ha and golden shiner (Noremigonus crysoleucas) fry at 321,100/ha into 16 earthen ponds at Rockefeller Wildlife Refuge, Grand Chenier, Louisiana. Four replicated treatments were tested: fed prawn monoculture, fed shiner monoculture, fed prawn and fed shiner polyculture, and unfed prawn fed shiner polyculture. The study lasted 149 days. There were no significant differences in growth between prawns fed in monoculture and prawns fed in polyculture (P > 0.05). However, fed prawns grew significantly larger (P < 0.05) than unfed prawns. Prawn survival in all treatments combined averaged 63%. Survival was significantly higher (P < 0.05) for fed prawns than for unfed prawns. Prawn yields averaged 533 kg/ha, when all treatments were combined. Yield was significantly higher (P < 0.05) for prawns grown with shiners and for prawns that received supplemental feed. Growth was significantly higher (P < 0.05) for shiners grown with fed prawns than for shiners grown with unfed prawns. Shiner survival averaged 33% and was significantly higher (P < 0.05) in monoculture than in polyculture. Yield for all ponds averaged 392 kg/ha, with no significant differences between treatments (P > 0.05).     

Slow‐release Coated Copper Sulfate as an Algicide for Aquaculture

A coated copper sulfate algicide designed for controlled release of copper was evaluated for its effectiveness in controlling phytoplankton in hybrid catfish, ♀Ictalurus punctatus × ♂Ictalurus furcatus, ponds. Copper concentrations were greater in ponds receiving weekly treatments with copper sulfate crystals than in ponds in which the coated copper sulfate was suspended in porous bags and left in ponds during the study. However, the coated copper sulfate treatment provided a similar degree of phytoplankton control for a period of about 4 mo. Copper additions did not negatively affect catfish survival, production, or feed conversion in either the copper sulfate crystal treatment or in the coated copper sulfate treatment as compared with the control (P > 0.05). Flavor scores for fish did not differ between control and treatments (P > 0.05). The coated copper sulfate appeared to be a potentially effective method for controlling phytoplankton in aquaculture ponds. It would be easier to apply and require fewer applications, and the coated copper algicide would not present a fish toxicity issue that can arise from high copper concentration immediately following copper sulfate crystal treatment.     

The use of model ponds to evaluate phytoplankton blooms and benthic algal mats for Penaeus monodon Fabricius culture

Abstract. Fibreglass pools (3·5m diameter, 1·2m high) were evaluated as model ponds and used to compare the effects of fertilization strategies, designed to promote either phytoplankton blooms or benthic algal mats, on production of Penaeus monodon Fabricius and water quality over 8 weeks. As production results were similar to those reported from commercial ponds in Australia and Taiwan, the pools were considered appropriate experimental units for assessing pond management strategies. Large blooms of filamentous algae developed in four of the eight pools with benthic algae. In these, individual prawn growth (weight gain), biomass gain, food conversion efficiency and drain harvest efficiency were all lower ( P < 0·05) than in pools with phytoplankton. Abundance of filamentous algae was negatively correlated ( P < 0·05) with prawn weight gain (r =−0·80) and drain harvest efficiency (r =−0·76). Differences in water quality arising from alternative fertilization strategies occurred but did not explain differences in prawn production indices. The results indicate that ponds used for monoculture of P. monodon should be fertilized so as to stimulate and maintain phytoplankton blooms and to discourage blooms of filamentous algae.     

The Effects of Fertilization and Water Management on Growth and Production of Nile Tilapia in Deep Ponds During the Dry Season

Abstract— Fertilization guidelines developed for shallow ponds (1 m) with controlled depths were tested in deeper (2.5 m) ponds to determine effectiveness of these guidelines for culture of Nile tilapia Oreochromis niloticus . Twelve ponds of 2.5-m depth were used in four treatments: (A) weekly fertilization with water addition; (B) weekly fertilization without water addition; (C) one early fertilization without water addition; and (D) fertilization frequency dependent on nutrient concentrations, without water addition. Sex-reversed Nile tilapia were stocked at 2 fish/m² with an initial weight of 15 g, and harvested after 234 d. Depth of water declined from 2.4 m to 1.6 m over the experiment in ponds without water addition. Fish growth rate was significantly higher in treatments A and B (0.86 g/d), than in other treatments, as was yield (3,830 kg/ha). Treatment C was lowest in growth (0.086 g/d) and yield (168 kg/ha), with treatment D intermediate. Fish growth rates and yields were strongly correlated to manure input ( R² = 0.89 and 0.94, respectively), and residuals were not correlated to any physical or chemical variables. Growth and yield in these deep ponds were somewhat lower than those in previous experiments for shallow ponds with regular water inputs. However, stagnant ponds did not accumulate nutrients and metabolites at rates higher than ponds with controlled water depths.     

Effects of Density Reduction and Supplemental Feeding on Stunted Crayfish Procambarus clarkii Populations in Earthen Ponds1

Density reduction, supplemental feeding, and a combination of two treatments were evaluated as means to alleviate stunting of red swamp crayfish Procambarus clarkii in earthen ponds. Mean total yield of crayfish in low density control ponds averaged 1,218 kg/ha and was 1.5 to 2 times higher (P≤ 0.05) than either the high density control or treatment ponds. Mean individual harvest weight of crayfish averaged 15.1 g and did not differ among treatments. Mean total yield of crayfish in ponds receiving supplemental feed was 32% higher than non-fed ponds (P≤ 0.05). Mean total yield and size of crayfish at harvest from reduced and non-reduced treatments did not differ. Density reduction and supplemental feeding implemented in early April did not increase individual crayfish weight to the commercially desirable size of 20 g.     

Split Ponds Effectively Overwinter Golden Shiners

Baitfish producers have expressed interest in adopting the split‐pond production system. However, confining fish to 20% of the pond area in split‐pond systems effectively quintuples fish density within the culture unit as compared with densities in open ponds. Winter conditions are known to be relatively more stressful on smaller fish, and high densities within split‐pond culture units could increase losses. A 139‐d study was conducted during the winter to compare the production of golden shiners, Notemigonus crysoleucas, in traditional earthen ponds and split ponds at two densities. Golden shiners were stocked at 646 kg/ha or 1292 kg/ha (ca. 370,500 or 741,000 fish/ha, respectively) into 12, 0.04‐ha, netted earthen ponds (six split ponds and six traditional). Feeding rate, nightly aeration hours, and daily circulation hours were reduced when water temperature decreased. At harvest, net yields were significantly lower in the split ponds as compared with traditional ponds at each density (53 and 113 kg/ha less in the low‐ and high‐density split‐pond treatments, respectively). Estimated survival was high (>87%) and did not differ among treatments. Results showed that, although net yield was reduced, small baitfish could be successfully overwintered in split‐pond culture units in preparation for the spring crappie market.     

POLYCULTURE OF CHANNEL CATFISH (Ictalurus punctatus) WITH ALL-MALE TILAPIA HYBRID

Channel catfish (Ictalurus punctatus) (x? = 0.8 g) and all-male hybrid tilapia fingerlings (Sarotherodon mossambica ♂ × S. hornorum ♀) (x? = 35.0 g) were stocked in 0.04 ha replicated ponds in Baton Rouge, Louisiana, in March and July 1981, respectively. The ponds were stocked at densities of 11,110 catfish per ha, 11,110 catfish with 5,550 tilapia per ha, 7,400 catfish per ha, and 7,400 catfish with 3,700 tilapia per ha. The fish were fed daily at 4% of estimated catfish biomass and were harvested in November 1981. There were no differences in dissolved oxygen or water temperature among the four culture systems (P > 0.05). The presence of tilapia, however, significantly increased water turbidity, pH and chlorophyll a concentrations (P < 0.05). Tilapia did not improve water quality and may have deteriorated it. Tilapia did not affect channel catfish growth or production (P > 0.05), but the presence of tilapia did significantly increase total fish yield (P < 0.05) by 13.5 and 32.2% at low and high catfish densities, respectively. Channel catfish and tilapia averaged 390 and 245 g at harvest, respectively. Overall catfish survival averaged 61%. Tilapia survival was 72% and 61% at low and high densities, respectively.     

The effects of phosphorus and nitrogen on phytoplankton dominance in tropical fish ponds

Nine ponds were used to determine the effects of phosphorus (P) and nitrogen (N) loading on the phytoplankton dominance in tropical fish ponds. Three ponds received triple superphosphate (TSP), three received triple superphosphate plus urea (TSP-Urea) and the rest served as the control. Addition of both phosphorus and nitrogen (TSP-Urea treatment) resulted in higher total phytoplankton than the TSP treatment and the control (P < 0.05). In general, blue-green algae formed the dominant group in TSP-Urea treatment ponds, followed by dinoflagellates, green algae, euglenoids and diatoms. In TSP-Urea treatment ponds, green algae was the most abundant group followed by blue-green, dinoflagellates, euglenoids and diatoms. Addition of combined nitrogen and phosphorus to the ponds not only significantly increased (P < 0.05) total phytoplankton densities, but also caused a shift from blue-green algal dominance to green algae. TSP treatment ponds showed significantly higher blue-green algae than TSP-Urea treatment in the early culture cycle. However, as the ponds became more productive with time, blue-green algae also appeared to be common in TSP-Urea treatment in spite of high N : P ratios. The blue-green algae increased linearly with the increase of total phytoplankton in all treatments (r²= 0.58, P < 0.01).     

Growth, Survival and Feed Conversion Rates of Sea Bream (Sparus aurata) Cultured in Earthen Brackish Water Ponds Fed Different Feed Types

Sparus aurata were cultured during an 8-month period in brackish water (salinity about 25 ppt) in an extensive culture system comprising eight earthen ponds, each with a water surface of 2.1 ha. Initial mean wet weight of fish in all ponds varied from 13.6 ± 1.9 to 19.2 ± 2.6 g/fish. The eight ponds were randomly allocated one of four experimental treatments (two ponds/treatment). In the first treatment, ponds were fertilized monthly with 100 kg urea and 50 kg triple super phosphate. The other treatments (2–4) were fed a locally produced tilapia pellet feed containing 25% crude protein made using different processes. Fish in the second treatment were fed tilapia feed pelleted by compressing machine, whereas in treatments 3 and 4 the pellets were produced by extruder machine (Wenger). Pellets in treatment 3 were floating and in the fourth were semi-sinking. Fish were fed pellets twice daily at 6% of their biomass. The mean final body weight for each treatment respectively was 104.6, 118.9, 156.8 and 158 g. Specific growth rate (SGR) of 0.8, 0.79, 0.99 and 0.95%/day, were obtained in ponds using only inorganic fertilizer, compressed sinking pellets, extruded floating pellets and extruded semi-sinking pellets, respectively. Feed conversion ratios (FCR) for treatments with the extruded tilapia pellets were 2.2 and 2.6 g feed/g gain, which were significantly (P < 0.05) better than treatments with compressed pellets (3.2 g feed/g gain). Production/ha/year were 1389, 1358, 945 and 682 kg fish for the groups fed with extruded floating, extruded semi-sinking, compressed and natural food, respectively. Under the present experimental circumstances, Sparus aurata fed extruded floating tilapia pellets (25% crude protein and 2,600 kcal/g), showed the best productive performance.     

Comparison of polyphosphate and orthophosphate as fertilizers for fish ponds

Sodium polyphosphate and triple superphosphate were used as sources of polyphosphate and orthophosphate, respectively, at equal P₂O₅ application rates in sunfish (Lepomis spp.) ponds. Filtrable orthophosphate and total phosphorus concentrations were generally higher in ponds treated with polyphosphate. However, differences between chlorophyll a concentration and net sunfish production did not differ between treatments (P > 0.05).     

Influence of pond fertilization and feeding rate on growth performance, economic returns and water quality in a small-scale cage-cum-pond integrated system for production of Nile tilapia (Oreochromis niloticus L.)

The effects of pond fertilization and feeding rate on growth, economic returns and water quality were investigated to develop a low‐cost cage‐cum‐pond integrated system for production of Oreochromis niloticus (L.). Hand‐sexed male fingerlings averaging 19±0.39 and 32±0.69 g were stocked in cages and open ponds at 150 fish cage^?1 and 2 fish m^?2 respectively. Fish were cultured for 114 days in five triplicate treatments. Cages were installed into ponds and caged fish were fed a 24% protein diet at 3% (T1) and 6% (T2) body weight day^?1 (BWD) without pond fertilization, and 6% BWD with pond fertilization (T3). The open water in the fourth treatment (T4) was not stocked but contained caged fish, which were fed 6% BWD for the first 57 days followed by 3% BWD for the remaining period. Ponds in the control (T5) had no cages and were neither fertilized nor open‐pond fish fed. Feeding rate and pond fertilization significantly (P<0.05) affected fish growth, profitability and water quality among treatments. Fish growth, feed utilization, fish yield, water quality and profits were significantly (P<0.05) better in T3 than the other treatments. It was concluded that fish production and economic returns were optimized at 6% BWD in fertilized ponds.     

Effects of tilapia (Oreochromis niloticus L.) stocking and artificial feeding on water quality and production in rohu–common carp bi‐culture ponds

Previous research showed that stocking 1.5 rohu (Labeo rohita) and 0.5 common carp (Cyprinus carpio) m⁻² yields the highest production in small holder ponds in Bangladesh. The present study looked into the effects of additional stocking of Nile tilapia (Oreochromis nilotica) in fed or non‐fed ponds on water quality and fish production. A low, additional stocking density of 0.2 Nile tilapia m⁻² was tested. All treatments were executed in triplicate in 100 m² ponds and the duration of the experiment was 4.5 months. The results showed that tilapia addition increased nutrient concentrations and reduced total suspended solid concentration and phytoplankton biomass (P<0.05). Tilapia stocking resulted in additional production without affecting the growth and production of rohu and common carp. Supplemental feeding increased the nitrogen and phosphorus concentrations, phytoplankton availability and the growth and production of rohu and common carp (P<0.01). The combination of supplemental feeding and tilapia stocking resulted in a higher net yield than the other treatments (P<0.05). Stocking 1.5 rohu, 0.5 common carp and 0.2 tilapia m⁻² in fed‐ponds is a good culture combination for polyculture farmers in South Asia.     

Re‐evaluation of Potassium Fertilization of Bluegill,Lepomis macrochirus,Ponds

An experiment consisting of eight potassium fertilization rates ranging from 0 to 60 kg K₂O/ha was conducted in earthen ponds stocked with bluegill, Lepomis macrochirus, at Auburn University in Alabama. Each pond also received nitrogen and phosphorus fertilization at 6 kg N and 3 kg P₂O₅/ha per application. After 11 fertilizer applications for over 7 mo, potassium concentrations in pond water ranged from 3.3 mg/L in control ponds to 38.9 mg/L in the pond receiving 60 kg K₂O/ha. The coefficients of determination (R²) between potassium fertilization rate and bluegill production and between potassium concentration in pond water and bluegill production were 0.039 and 0.071, respectively. Potassium fertilization appears unnecessary in bluegill ponds where water contains more than 2 mg/L of potassium.     

Evaluation of rice (Oryza sativa), volunteer vegetation,and alligatorweed (Alternanthera phyloxeroides) in various combinations as crawfish (Procambarus clarkii) forages

Four treatments of naturally occurring plants and planted rice were evaluated as forages in experimental crawfish ponds. Their relationships to biomass production, dawn dissolved oxygen, unstable water levels, and crawfish production were determined.Total standing biomass of forage at fall flooding was significantly lower (P < 0.01) for alligatorweed plus volunteer vegetation ponds compared with all other forage regimes. Average dawn dissolved oxygen during the first 5 weeks after flooding varied between 1.7 mg/l and 4.7 mg/l in ponds containing alligatorweed, compared with 1.0 mg/l and 1.5 mg/l in ponds containing other vegetation. Crawfish yields in kg/ha for ponds with stable water levels were: rice plus alligatorweed, 2852; rice only, 2652; rice plus volunteer vegetation, 2117. These forage treatments appeared to sustain the crawfish population, and stunting of crawfish at unmarketable sizes was not observed.     

Mineral fertilization of carp ponds in polycultural rearing

The fertilization of carp ponds as an important intensification means has been utilized in Europe since the first half of the 19th century, but even in most intensive fertilization the concentration of nitrogen (N) hardly exceeds 2 mg/l and of phosphorus (P), 0.5 mg/l.Polycultural carp growing using intensive mineral fertilization (weekly and every 3 days) has been experimented in the Freshwater Fishery Research Station in Plovdiv in the 1971–1972 period.The greatest zooplankton and benthos biomass and the greatest fish growth per ha water area are obtained with 3-day mineral fertilization with ammonium nitrate, 708 kg/ha and superphosphate, 395 kg per hectar. The average monthly water temperature in the experimental ponds during the vegetation period (June–September) fluctuates between 21.5 and 24.7°C. The oxygen dissolved (O₂) during the day hours changes within the average of 4.9–7.6 ml/l and the aeration is normal for the carp ponds (4.0–8.1 mg O₂/l). The highest average seasonal zooplankton biomass in mixed fertilization (mineral and organic) is 2.437 g/m³. The zooplankton is represented by the following variaties: Rotatoria — Brachionus calyciflorus; Copepoda — Acanthocyclops vernalis and Cladocera — Moina rectirostric. The benthos consists of: chironomid larvae (family Chironomidae, Diptera) and Oligochaetae. The highest average seasonal biomass of the benthos is established with three-day mineral fertilization, 1.472 g/m². The total fish growth with three-day fertilization is 300 kg/ha higher than in the control ponds (without fertilization). The best fishery results have been achieved with three-day fertilization giving a total growth of the fish of 2 730 kg/ha and a food coefficient of 2.8.     

伊乐藻管理对河蟹精养池藻类水华的防控作用

为探究河蟹(Eriocheir sinensis)精养池塘中伊乐藻(Elodea nuttalli)管理对藻类水华的预防和控制作用,2017年6月10日至10月25日在上海泖港地区河蟹精养池塘进行试验。实验设置处理组(控制植株高度30 cm)和对照组(控制植株在水面以下20 cm)。对池塘水质进行监测,利用回归分析判别水质理化因子与Chl-a浓度之间的关系。结果显示,对照组水体Chl-a的平均浓度是处理组的4.66倍(P0.01),且TP、PO_4-P、T、pH、DO和SD都显著高于处理组(P0.05),两组的Chl-a浓度与TP、PO_4-P、T、pH、DO呈显著的正相关,与SD呈显著的负相关(P0.01),处理组Chl-a浓度还与NO_3-N具有显著的正相关性(P0.05),与COD_(Mn)、NH_4-N、NO_2-N、TN、TN/TP不相关,说明营养物质特别是TP和PO_4-P的增多一定程度上会促进藻类的生长,河蟹精养池对伊乐藻的管理比常规处理能够更有效地抑制藻类生长,从而达到生态养殖的目的。