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1.
Abstract Hatchery-reared age-0 red snapper, Lutjanus campechanus (Poey), were released onto artificial habitats in the Gulf of Mexico. Fish showed 12.7% survival after 7 months on small habitats (0.86 m3 ) and 3.1% survival after 8 months on large habitats (3.9 m3 ). Emigration was estimated by the movement of fish to unstocked habitats and accounted for 76.8% of the total decline in abundance at release sites after 26 days. Fish showed higher survival and growth rates on small habitats (27.6% at 26 days; 0.33 mm day−1 ) compared with large habitats (13.2% at 34 days; 0.26 mm day−1 ), which may have been due to increased predation and competition on large habitats. Fish became evenly distributed among adjacent habitats 26 days after release, indicating that stocking densities at release habitats were above carrying capacities. These observations suggested that providing additional habitat around red snapper release sites would increase survival. 相似文献
2.
Annual net production of the five Sargassaceae species in Yoro,western Wakasa Bay,Sea of Japan 总被引：1，自引：0，他引：1
ABSTRACT: Annual net production of the five Sargassaceae species was investigated in Yoro, western Wakasa Bay, Sea of Japan. The Sargassaceae species were collected at a depth of 2.0–2.5 m and subjected to stratified clipping for 13 months. Annual net production was estimated at 2407 g dry wt/m2 for Sargassum patens , 2132 g dry wt/m2 for Sargassum macrocarpum , 1458 g dry wt/m2 for Sargassum siliquastrum , 1197 g dry wt/m2 for Myagropsis myagroides , and 1471 g dry wt/m2 for Sargassum piluliferum . The ratio of annual net production to maximum biomass (P/Bmax ) for these species ranged between 1.3 and 1.7, being higher than in previous studies which used the same method. Winter storms with strong wave exposure and relatively calm condition in Yoro were considered to augment P/Bmax . The total losses estimated from the different units of stratified clipping were compared. If larger and less segregated units were applied, the total loss would decrease. It was suggested that a 50 cm stratum would be applicable to the larger species (3 m or longer) and a stratum of 20 cm or less would be applicable to mid-sized or smaller species (less than 3 m). 相似文献
3.
Kyoko Kinoshita Sayaka Tamaki Miho Yoshioka Sarawut Srithonguthai Tadao Kunihiro Daigo hama Kouichi Ohwada Hiroaki Tsutsumi 《Fisheries Science》2008,74(1):77-87
ABSTRACT: For bioremediation of organically enriched sediment deposited below fish farms, the extremely high potential for population growth of a deposit-feeding polychaete, Capitella sp. I, in the organically enriched sediment, and the effect on decomposition of organic matter in the sediment, were examined. A mass-culturing technique was conducted for this species. Bioremediation experiments were conducted on the organically enriched sediment in a fish farm in Kusuura Bay, Japan in 2003–2006. Approximately 1.7 million individuals of the worms were placed on the sediment below one net pen in December 2003, 9.3 million individuals in November 2004, and 2.2 million individuals in November 2005. After the worms were spread on the sediment, they rapidly increased in number and reached the highest densities of approximately 134 000 inds/m2 in February 2004, 527 000 inds/m2 in March 2005 and 103 000 inds/m2 in January 2006. In the process of rapid population growth, the decomposition of the organic matter of the sediment was enhanced markedly. Our results demonstrate that the promotion of population growth by spreading cultured colonies of Capitella can enhance the decomposition rate of organic matter markedly in organically enriched sediment below fish farms. This method is promising for minimization of the negative effects of fish farms. 相似文献
4.
Yousef S. Al-Hafedh Aftab Alam Mohamed Salaheldin Beltagi 《Journal of the World Aquaculture Society》2008,39(4):510-520
An indoor aquaponic system (i.e., the integration of fish culture with hydroponic plant production in a recirculating setup) was operated for maximizing water reuse and year-round intensive food production (Nile tilapia, Oreochromis niloticus , and leaf lettuce) at different fish feed to plants ratios. The system consisted of a fish culture component, solid removal component, and hydroponic component comprising six long channels with floating styrofoam rafts for holding plants. Fish culture effluents flowed by gravity from the fish culture component to the solid removal component and then to the hydroponic component. Effluents were collected in a sump from which a 1-horsepower in-line pump recirculated the water back to the fish culture tanks at a rate of about 250 L/min. The hydroponic component performed as biofilter and effectively managed the water quality. Fish production was staggered to harvest one of the four fish tanks at regular intervals when fish attained a minimum weight of 250 g. Out of the total eight harvests in 13 mo, net fish production per harvest averaged 33.5 kg/m3 of water with an overall water consumption of 320 L/kg of fish produced along with the production of leaf lettuce at 42 heads/m2 of hydroponic surface area. Only 1.4% of the total system water was added daily to compensate the evaporation and transpiration losses. A ratio of 56 g fish feed/m2 of hydroponic surface effectively controlled nutrient buildup in the effluents. However, plant density could be decreased from 42 to 25–30 plants/m2 to produce a better quality lettuce. 相似文献
5.
Abstract – This research characterised feeding ecology of fishes associated with patches of Egeria najas and Egeria densa , two submerged macrophytes, in Rosana Reservoir, Upper Paraná River basin, Brazil. Fishes were sampled using a 1 m2 throw trap in patches of different macrophyte biomass and in three diel periods during a wet season. Fish diet (10 species) was primarily composed of autochthonous items (zooplankton, algae and aquatic insect larvae). Almost all intra-specific diet patterns had moderate to low levels of diet similarity, indicating a high variability in diet. Some species showed no diel patterns in feeding activity, whereas others were primarily diurnal or nocturnal. No differences in feeding activity were observed among habitats of medium and high macrophyte biomasses, and species tended to feed on the same items among these habitats. The most abundant fish species demonstrated low inter-specific diet overlap and appear not to compete for food resources. We suggest that Egeria patches are feeding grounds and shelter for small-sized fish species. 相似文献
6.
Four diets (T0 –T3 ) were formulated reducing the fishmeal (Indian) component by 100 g kg–1 from 300 to 0 g kg–1 and including proportionately increasing quantities of maize. Diets were fed for 120 days at 50 g kg–1 body weight to triplicate groups of common carp (av. wt. 2.11–2.18 g) stocked at 1 m–2 in mud bottomed cement tanks (18 m2 ), fertilized with poultry manure. Fish growth, SGR and FCR in the different treatments were statistically not significantly different ( P > 0.05). PER was lowest for the 300 g fishmeal kg–1 diet treatment (diet T0 ), increasing with decrease in dietary fishmeal content (diets T1 –T3 ). Fish survival ranged from 96.29 to 100%. Diets influenced carcass composition and digestive enzyme activity. A significant increase in lipid deposition was recorded with increasing dietary carbohydrate content. Amylase, protease and lipase activities were higher in fish fed with diets T2 and T3 . The protein sparing effect of dietary carbohydrate and the economic implication of eliminating fishmeal from the diet are discussed. 相似文献
7.
Abstract— Large piscivorous fish are assumed to affect habitat selection and food intake of prey fish. To study the effects of cannibalistic Arctic charr, Salvelinus alpinus (L.), on smaller stunted charr, we sampled the prey fish in littoral and pelagic habitats using gill nets, before and shortly after the release of large charr in a small lake (0.52 km2 ). In the habitats where the risk of predation was highest, the catch per unit effort de creased from 13.3 to 4.8 fish per 100 m2 of gillnet after release of pred ators. The large decrease in numbers of charr < 18 cm corresponded with the predicted vulnerable prey sizes, according to a model based on the size distribution of predators. The occurrence of planktivorous fish and weight-specific food intake decreased in the high risk habitat and remained unaffected in the low risk habitats. Changes in the food intake of prey fish could not be explained in terms of fish length, indicating that prey fish changed diet when the risk of predation was high. 相似文献
8.
Levy C. Gomes Rodrigo Roubach Carlos A. R. M. Araujo-Lima Adriana R. Chippari-Gomes Nívia P. Lopes Elisabeth C. Urbinati 《Journal of the World Aquaculture Society》2003,34(1):76-84
The increased demand for juvenile tambaqui Colossoma macropomum for grow-out ponds and stocking programs in the Amazon state of Brazil has increased the transportation of this species. This study was designed to determine the optimum density of juvenile tambaqui during transportation in closed containers. Fish (51.9 ± 3.3 g and 14.9 ± 0.4 cm) were packed in sealed plastic bags and transported for 10 h at four densities: 78, 156, 234, and 312 kg/m3 . After transportation, fish from each density were kept in separate 500-L tanks for 96 h. Mortality, 96-h cumulative mortality, water quality, and blood parameters (hematocrit, plasma cortisol, and glucose) were monitored. Fish mortality after transportation was significantly lower at densities of 78 and 156 kg/m3 than at 234 and 312 kg/m3 . Cumulative mortality was significantly lower at a density of 78 kg/m3 . Dissolved oxygen after 10 h of transportation remained high at a density of 78 kg/m3 , but reached critically low values at all other densities. Ammonia concentration was highest at the lowest density and was lower at higher densities. Carbon dioxide concentration was lowest at the density of 78 kg/m3 but higher in the other treatments. Plasma glucose and cortisol increased significantly immediately after transportation at densities of 156, 234, and 312 kg/m3 , returning to control values by 24 h. The best density for juvenile tambaqui during a 10-h transportation haul in a closed container was 78 kg/m3 . At this density there was no fish mortality, water quality was kept within acceptable values, and fish were not stressed. 相似文献
9.
Mohammed Saif Abdullah Thong Onn Wuan Shogo Kawahara 《Journal of the World Aquaculture Society》1987,18(4):237-241
The results of two stocking density trials on the nursery and grow-out stages of Epinephelus tauvina (Family: Serranidae), in PVC-lined raceways are presented.
At the nursery stage, fry of 17.1 g initial mean weight showed no significant differences in growth rate, survival rate and condition factor when stocked at densities of 200 and 400 fish/m3 over a period of 52 days. Fish grew to mean weights of 61.7 and 63.7 g, giving growth rates of 0.86 and 0.90 g/fish/day and final biomasses of 12.1 and 2S.2 kg/m3 for densities of 200 and 400 fish/m3 , respectively. Survival rates were excellent for both treatments at 98percnt; or greater. Food conversion efficiency was slightly improved at the higher density.
At the grow-out stage, E. tauvina of mean weights ranging from 150-170 g cultured for a period of 215 days grew better at a density of 5 fish/m3 than at densities of 20 and 60 fish/m3 (final size: 770, 560 and 450 g with growth rates of 2.8, 1.8 and 1.4 g/fish/day, respectively). Survival rates were higher at the two lower densities. Overall, total biomass increased with stocking density (3.9, 11.1 and 23.4 kg/m3 , for 5, 20 and 60 fish/m3 , respectively). These results indicate that hamoor has potential to be successfully cultured in raceways. 相似文献
At the nursery stage, fry of 17.1 g initial mean weight showed no significant differences in growth rate, survival rate and condition factor when stocked at densities of 200 and 400 fish/m
At the grow-out stage, E. tauvina of mean weights ranging from 150-170 g cultured for a period of 215 days grew better at a density of 5 fish/m
10.
2016年8月,现场调查并分析了山东省威海市双岛湾海域的海草资源及其生态特征,发现分布面积为442.19hm2的海草床,种类为鳗草(Zostera marina)和红纤维虾形草(Phyllospadix iwatensis) 2种。鳗草的分布面积约为434.46 hm2,占总面积的98.3%,主要分布在双岛湾中部东侧及海参池,其平均植株密度和生物量分别为(174.2±9.2) shoots/m2和(337.7±17.5) g DW/m2。红纤维虾形草的分布面积约为7.73 hm2,占总面积的1.7%,主要分布在双岛湾湾口东侧及向东约3 km的近岸礁石浅水区,呈明显的带状分布,其平均植株密度和生物量分别为(889.1±17.1)shoots/m2和(605.9±18.1) g DW/m2。双岛湾海草床平均水深约为1.6 m,鳗草草床底质坚硬,平均底质粒径约为(4.3±0.2)mm。本调查表明,双岛湾海草床受到陆源污染物排放、围海养殖和捕捞作业等人类活动的严重威胁,提出了保护双岛湾海草床的建议和对策,为我国海草床现有资源提供数据补充。 相似文献
11.
Abstract. A preliminary study was conducted to assess the performance of the tilapia, Oreochromis spilurus (Günther), cultured in seawater cages at different stocking densities during the nursing and rearing phases. The stocking densities tested were 200, 400 and 600 fish/m3 during the nursing phase and 100, 200, and 300 fish/m3 during the rearing phase.
In both growth phases, no significant differences (P>0.05) were observed among the different stocking densities on the mean individual final weight, daily growth rate, feed conversion ratio and survival rate. Yields in cages stocked with 400 and 600 fish/m3 during the nursing phase, however, were significantly (P<0.05) higher compared with cages stocked with 200 fish/m3 . No significant differences (P>0.05) were observed between 400 and 600 fish/m3 . A density of 600/m3 is therefore considered to be optimum for the nursing phase.
Yields of cages during the rearing phase increased significantly (P<0.01) with the increase in stocking density. After grading the fish, however, no significant differences (P>0.05) were observed when only fish bigger than 150g were considered. The occurrence of exophthalmia (cataract) was observed in two of the four replicates at the highest stocking density (300 fish/m3 ) during the rearing stage. Therefore, a stocking density of 200 fish/m3 is considered optimum for the rearing phase. 相似文献
In both growth phases, no significant differences (P>0.05) were observed among the different stocking densities on the mean individual final weight, daily growth rate, feed conversion ratio and survival rate. Yields in cages stocked with 400 and 600 fish/m
Yields of cages during the rearing phase increased significantly (P<0.01) with the increase in stocking density. After grading the fish, however, no significant differences (P>0.05) were observed when only fish bigger than 150g were considered. The occurrence of exophthalmia (cataract) was observed in two of the four replicates at the highest stocking density (300 fish/m
12.
Abstract – This study investigated the habitat use of 0+ pike (9–17 cm) in relation to two different water transparency regimes (clear water/chlorophyll water), two different light regimes (day/night) and the presence/absence of prey using 16 m2 experimental ponds. Pike could freely choose between two structured habitats (a simple structured and a complex structured), an interface habitat (between the structured habitats and open water) and an open water habitat. Foraging success of the pike in relation to water transparency was investigated by comparing mean condition (Fultons K ) of the pike as well as the number of surviving prey fish. Habitat use was influenced by the presence/absence of prey and varied between waters with different transparency. The presence of prey intensified the use of structural habitats of 0+ pike in both clear and chlorophyll waters. A preference for complex habitats was found in clear water and was presumably related to foraging. The pike in chlorophyll water, in contrast, appeared more evenly distributed among all habitats, as illustrated by a more intensive use of open water in chlorophyll water compared to the clear water. No detectable impact of water transparency on the foraging success of 0+ pike was found. 相似文献
13.
Abstract.
The study was conducted to develop guidelines for high-density overwintering of tilapia in tanks using warm underground sea water. Seawater-acclimated fish of 20 g were stocked in 36 tanks at 250, 500 and 750/m3 . Water flow was regulated at 0.1 and 0.2 l/kg fish/min. Fish were fed at the rates of 0.75% and 1.0% of biomass per day.
After 135 culture days, the mean individual weight gain and specific growth rate decreased, whereas feed conversion increased significantly ( P <0.0001) with the increase in stocking density. The condition factor at 500 and 750 fish/m3 was significantly lower ( P <0.0005) than at 250 fish/m3 . However, stocking density had no significant effect on the survival rate. Significantly better specific growth rate, condition factor and feed conversion were observed at a water flow rate of 0.2 l/kg fish/min than at 01 l/kg fish/min. Significantly higher mean individual weight gain, specific growth rate, and survival rate were observed at 1.0%/day than at the 0.75%/day feeding rate. The findings indicate that the optimum stocking density for overwintering tilapia in tanks using warm underground sea water is 750 fish/m3 with a water flow rate of 0.1 l/kg fish/min and a feeding rate of 0.75%/day. 相似文献
The study was conducted to develop guidelines for high-density overwintering of tilapia in tanks using warm underground sea water. Seawater-acclimated fish of 20 g were stocked in 36 tanks at 250, 500 and 750/m
After 135 culture days, the mean individual weight gain and specific growth rate decreased, whereas feed conversion increased significantly ( P <0.0001) with the increase in stocking density. The condition factor at 500 and 750 fish/m
14.
Fishery resources and economic gain in three mangrove areas on the south-east coast of India 总被引：2，自引：0，他引：2
Abstract The fishery resources and fishing income in three different mangrove areas were evaluated. The mangrove-rich area provided high catches of shellfish and finfish and yielded high fishery income, compared with the mangrove-poor areas. Luxuriant mangrove areas supported a catch of 11 kg shellfish ha−1 day−1 and 4.5 kg finfish ha−1 day−1 , corresponding with an economic gain of US$ 14 (Rs 603.7) day−1 for shellfish and US$ 3 (Rs 130.5) day−1 for finfish. The value of maintaining mangroves to ensure better fishery resources and to support coastal economies was identified. Management practices for conserving and enhancing mangroves and associated fishery resources are suggested. 相似文献
15.
ABSTRACT: An apparatus to measure the locomotor activity of aquatic benthic organisms at variable low light levels was developed and the diurnal behavioral pattern of the abalone Haliotis discus discus was measured at various low light intensities. During the experiment, abalone were exposed to 12 h light–dark cycles of complete darkness, 0 µmol/m2 /s throughout the 12 h dark cycle and, during periods I (days 1–8) and III (days 19–26), the 12 h light cycles were set at 10 µmol/m2 /s. During period II (days 10–17), abalone were exposed to a light level during the 12 h light cycles of 1 × 10−5 , 1 × 10−6 , 1 × 10−7 or 1 × 10−8 µmol/m2 /s and the changes in locomotor activity assessed. At daytime levels of 1 × 10−5 µmol/m2 /s, typical behavioral patterns were observed of high locomotory activity during the night-time cycle. However, at lower light intensities, the distinction between day and night activity patterns became less clear and, at intensities lower than 1 × 10−7 µmol/m2 /s, the difference between activity during the light and dark cycles became negligible. Based on this, we conclude that the threshold of light level perception in relation to locomotor activity is approximately 1 × 10−7 µmol/m2 /s. The significance of these results in relation to the entrainment of behavior in abalone is discussed. 相似文献
16.
Effects of Diffused Aeration and Stocking Density on Growth, Feed Conversion, and Production of Florida Red Tilapia in Cages 总被引：1，自引：0，他引：1
John A. Hargreaves James E. Kakocy Donald S. Bailey 《Journal of the World Aquaculture Society》1991,22(1):24-29
The effects of four levels of diffused aeration (0, 6, 12, and 24 hours/day) and two stocking densities (400 and 600 fish/m3 ) on the culture performance of caged Florida red tilapia were evaluated in 1 m3 cages in a 2 ha watershed pond on St. Croix, U.S. Virgin Islands. Fish obtained a nutritionally-complete (36% protein), floating feed from demand feeders for 143 to 146 days. Diffused aeration had no significant ( P > 0.05) effect on fish growth, survival, feed conversion, and production in cages. Combined across all levels of diffused aeration, fish stocked at 400/cage had a greater growth rate (2.21 vs. 1.97 g/day), larger final body weight (370 vs. 335 g), and a lower feed conversion ratio (1.69 vs. 1.80) than fish stocked at 600/cage ( P < 0.05). The final biomass of fish stocked at the higher density (181 kg/m3 ) was greater than at the lower density (140 kg/m3 ). The enhancement of water exchange rates by diffused aeration did not increase tilapia growth rate or production in cages. 相似文献
17.
Abstract.— Densities of 9 tilapia (hybrid Oreochromis mossambicus × O. urolepis hornorum)/m3 gave the highest production among five densities (1, 3, 6, 9, and 12 fish/m3 ) tested in a pulsed-flow culture system. Culture of fish in irrigation ditches may have great potential for integrating fish farming with irrigated agriculture. Each 1,000 meters of ditch could potentially produce up to 1,400 kg of tilapia during a 112-d growing season. 相似文献
18.
M.S. KHAN 《Aquaculture Research》1994,25(7):753-760
Abstract. Six groups of tropical freshwater catfish, Mystus nemurus (Cuvier & Valenciennes)(mean weight. 20·45 ± l·5g), were reared in 0·34m3 fibreglass tanks at different stocking densities (105, 195, 285, 375, 465 and 555 specimens/m3 water) for 84 days. The objective of the study was to determine the effect of various stocking densities on the growth, nutrition, biochemical composition and survival of M. nemurus. The lowest growth rate appeared in fish at the highest density and the highest was observed in fish stocked in moderate density of 285 and 375 fish/m3 water. Fish production was also lower at relatively low stocking densities of 105 and 195 fish/m3 . Food conversion ratio (FCR), protein efficiency ratio (PER) and biochemical composition of M. nemurus indicate that there exists an optimum stocking density which lies between 285 and 375 fish/m3 . 相似文献
19.
Abdul Qayyum Siddiqui Yousef S. Al-Hafedh Ahmed H. Al-Harbi Seikh A. Ali 《Journal of the World Aquaculture Society》1997,28(1):106-112
Abstract This study was conducted to evaluate the effects of stocking density and monosex culture on growth, survival, yield and feed conversion ratio of freshwater prawn Macrobrachium rosenbergii in concrete tanks. Juvenile prawns with an average weight of 1.8 g were stocked into triplicate tanks at densities of 5, 10, 15 and 20 prawns/m2 , grown for 168 d and fed a 34% tilapia diet. Stocking density had significant effect on prawns. Final mean body weight decreased with the increasing density, being highest at 5 prawns/m2 (29.6 9). and lowest at 20 prawns/m2 (17.4 g). Total yield increased from 135 g/m2 (1,350 kg/ha) at a density of 5 prawns/m2 to 261 g/m2 (2,610 kg/ha) at density 15/mz to 245 g/m2 (2,450 kg/ha) at 20/mz . Feed conversion ratios were high and ranged from 3.7 (5 prawns/m2 ) to 5.6 (20 prawns/m2 ).
In monosex culture of freshwater prawns stocked in triplicate tanks at a density of 5 prawns/m2 for 112 d, the all-male population had the best growth performance and feed conversion ratio, followed by the mixed-sex and all-female populations. The all-male population had 99% marketable prawns (>20 g) with an average yield of 159 g/m2 (1,590 kg/ha); the mixed-sex population had 90% marketable prawns and the yield was 135 g/mz (1,350 kg/ha); and the all-female population had 75% marketable prawns with an average yield of 108 g/m2 (1,080 kgha). 相似文献
In monosex culture of freshwater prawns stocked in triplicate tanks at a density of 5 prawns/m
20.
The influence of different levels of dietary vitamin E on sea bass Dicentrarchus labrax flesh quality 总被引：3，自引：0，他引：3
Sea bass Dicentrarchus labrax fillet quality was investigated after feeding with four diets (A, B, C or D) containing different levels of dietary vitamin E (139 mg kg–1 , 254 mg kg–1 , 493 mg kg–1 and 942 mg kg–1 , respectively). Six-hundred and eighty fish (mean initial weight 208 g) were equally divided into four 20 m3 tanks and fed for 87 days. Filtered seawater with a temperature ranging from 18.2 to 26.3 °C was supplied continuously. At the end of the experiment, fish were stored at 1 °C for 12 days. At one, three, six, nine and 12 days, 20 fish per group were processed for proximate composition, vitamin E and induced thiobarbituric acid reactive substances (TBARs) analyses. No significant differences in proximate composition were registered between groups. The flesh lipid content ranged from 88.0 g kg–1 (group B) to 96.8 g kg–1 (group A). Vitamin E fillet content was significantly different between groups, reaching levels of 98.0, 150.7, 225.2 and 302.0 μg g–1 lipids for group A, B, C and D, respectively. Induced TBARs values were statistically different only for group A compared with the other groups. No significant variations were registered in relation to preservation time. Because of the positive influence of vitamin E on seafood quality and the correlation between its dietary level and flesh deposition, the α-tocopherol content of the diet should be well above fish minimum requirements. 相似文献