Culture-based fisheries in small reservoirs in northern Vietnam: effect of stocking densities and species combinations

This study was conducted in 20 reservoirs, ranging in size from 4 to 30 ha, in the mountainous, northern region of Vietnam, in ThaiNguyen and YenBai provinces, over two growth cycles in 2002/03 and 2003/04. The reservoirs are leased by farmers for fishery activities from the provincial administration, and the trials were managed by the lessee farmers. Three species combinations in ratios (by fingerling weight) of grass carp: silver carp: bighead carp: common carp: mrigal 1:2:1:1:3 (A), 1:3:1:1:2 (B) and 1:2:1:1:2 (C) were used as seed stock. The overall mean yield of stocked fish in 2002/03 and 2003/04 growth cycles in reservoirs in ThaiNguyen and YenBai provinces was 165 (±21) and 190 (39), and 287 (±22) and 325 (±24) kg ha⁻¹ respectively. The yield in reservoirs in both provinces, in both growth cycles and irrespective of the species combinations, increased in relation to stocking density. In reservoirs in ThaiNguyen Province, the species combination B gave the lowest yield (both growth cycles and overall), and differed significantly (P<0.05) from combinations A and C. The stocking efficiency (ratio of the yield of stocked fish in kg ha⁻¹ to the weight of the stocked fish in kg ha⁻¹) in reservoirs in ThaiNguyen Province ranged from 2.9 to 5.1 over the two growth cycles and that in YenBai from 2.8 to 3.9. There was no discernible trend between growth cycles and/or between species combinations. The major cost incurred was for fingerling procurement. In all instances, a net profit was accrued. The mean (±standard error (SE)) net profit ha⁻¹ (in 103VN dong; approximately 15 500 VND=1 US$) was 885 (±270) and 864 (±214), and 1322 (±176) and 1600 (±150) for the growth cycles 2002/03 and 2003/04 for reservoirs in ThaiNguyen and YenBai provinces respectively. Between the two growth cycles, the net profit increased in eight and three reservoirs from YenBai and ThaiNguyen, respectively, the maximum increase being recorded in Khuan Gio (165%) and Dong Man (39%) reservoirs.

Culture-based fisheries in non-perennial reservoirs of Sri Lanka: influence of reservoir morphometry and stocking density on yield

Culture-based fish yield in non-perennial reservoirs of Sri Lanka was related to reservoir morphometry and stocking density. The reservoirs were stocked mainly with fingerlings of one Chinese and three Indian major carp species, common carp, Cyprinus carpio L., and the genetically improved farmed tilapia strain of Nile tilapia, Oreochromis niloticus (L.), at four pre-determined species combinations and a range of stocking densities [SD (fingerlings ha⁻¹)]. Twenty-three reservoirs were harvested successfully at the end of the culture period of 2002–2003. Basic limnological and morphometric parameters, including shoreline development (D_L) and shoreline area ratio (R_LA), were estimated for each of the 23 reservoirs. Bray–Curtis similarity and non-metric multidimensional scaling using mean values of limnological data revealed that reservoirs could be ordinated into two major clusters, one with intact sample distribution due to similar trophic characteristics and the other with scattered sample distribution. Reservoirs in the cluster with similar trophic characteristics showed significant correlation (P < 0.05) between R_LA and total fish yield (Y). A multiple regression equation, Y = −693 + 4810 R_LA + 0.484 SD, was generated to estimate fish harvest in relation to SD.

Consequences of intraspecific seed-size variation in Sparganium emersum for dispersal by fish

1. The potential for seed dispersal by fish (ichthyochory) is likely to vary within aquatic plant species, depending on intraspecific variation in phenotypic seed traits.

2. We studied the effect of seed size variation within the unbranched burreed (Sparganium emersum) on the potential for internal dispersal by the common carp (Cyprinus carpio), by feeding them light (< 10 mg), medium (10–20 mg) and heavy ( > 20 mg) seeds, seed mass being positively related to seed size.

3. We hypothesized: (i) that ingestion, retention time, survival during gut passage and viability after gut passage of S. emersum seeds would be affected by seed size; and (ii) that this would translate into intraspecific variation in dispersal probability and dispersal distance among seed size categories.

4. Ingestion was negatively related to seed size, while survival during gut passage was positively related to seed size. Seed viability after gut passage was not affected by seed size. Since the negative effect of ingestion was counterbalanced by an equally strong but positive effect on seed survival, the probability of dispersal did not differ between the tested seed-size categories.

5. The time that seeds remained in the digestive tract of carp did not differ between seed sizes, suggesting equal potential dispersal distances for all seeds. Based on optimum swimming speeds of carp, ranging from 0·9 to 1·8 km h−1, maximum dispersal distances will most likely range from 13·5 to 27 km.

6. This study highlights the importance of studying all stages of the endozoochorous dispersal process in order to estimate the effect of a phenotypic seed trait on plant dispersal.

Determinação da toxicidade aguda e caracterização de risco ambiental do herbicida Roundup (glifosato) sobre três espécies de peixes

Considering their commercial importance, as these are the species of freshwater fish more commercialized in Brazil, their occurence in different kinds of aquatic environments (lakes, rivers and dams) and for being tolerant to a wide range of variation of various physical parameters and chemical water, the fish species Oreochromis niloticus, Cyprinus carpio and Colossoma macropomum were chosen for this study, furthermore, to test the toxicity we used the herbicide Roundup. The fingerlings of tilapia (Oreochromis niloticus), commun carp (Cyprinus carpio) and tambaqui (Colossoma macropomum) were submitted to the herbicide roundup in the following concentrations: 0.0 (control); 18,06; 19,10; 20,14; 21,18 and 22,22 mg.L-1, 0.0 (control); 13,89; 14,86; 15,83; 16,81 and 17,78 mg.L-1, and 0.0 (control); 18,06; 19,10; 20,14; 21,18 and 22,22 mg.L-1, respectively, three for 96 hours. The LC50 - 96h for O. niloticus, C. carpio and C. macropomum was 21,63, 15,33 and 20,06 mg.L-1 of the herbicide roundup, respectively. The results show that this herbicide is classified as slightly toxic to the three species. The values of dissolved oxygen, pH and temperature recorded in the aquarium control and aquarium experimental of the three fish species have remained without significant variations during the tests, which reduces the possibility of death caused by sudden variations of these parameters during the 96 hours the experiment. The values of LC50 between different species of fish were observed, noting that the species O.niloticus, C. carpio and C. macropomum showed no expressive differences. The values of environmental risk of Roundup were calculated to obtain more stringent parameters in assessing the dangerousness of those on nontargets. The risk of environmental contamination by Roundup for the Nile tilapia, common carp, and tambaqui are low for the lowest application rate (1 L.ha-1) and depths (1.5 and 2.0 m). The dilution of 100%, the highest recommended dose (5 L.ha-1) and depths (1.5 and 2.0 m) the risk is moderate for the three species. The values of the Risk Ratio (QR) were greater than 0,1, indicating that the values of the CAE and LC50 are above acceptable levels and there is a need, this study, a refinement in ecotoxicological tests

Consórcio suíno-peixe: aspectos ambientais e qualidade do pescado

Amostras de músculo de carpa comum (Cyprinus carpio) e de água de três viveiros fertilizados com dejetos de suínos e de um viveiro em que os peixes foram alimentados com ração comercial para peixes foram analisadas durante seis meses. O objetivo foi observar a presença de bactérias patogênicas, como Salmonella, Staphylococcus aureus e coliformes totais e fecais, em peixes comercializados in natura no município de Chapecó, Santa Catarina. Foram aferidos quinzenalmente, na água dos quatro viveiros, oxigênio dissolvido, pH, turbidez, alcalinidade total, dureza total, amônia, nitrato e ortofosfato, bem como a quantidade de coliformes totais e fecais. A análise microbiológica músculo dos peixes demonstrou ausência de Salmonella em todas as amostras. A contagem dos demais microrganismos manteve-se inferior ao limite máximo permitido pela legislação vigente, em todas as amostras. Portanto, os peixes analisados estavam aptos ao consumo humano, pois atenderam aos padrões recomendados pela Divisão Nacional de Vigilância Sanitária de Alimentos (DINAL). A comparação entre os viveiros fertilizados com dejetos de suínos e o viveiro fertilizado com ração comercial para peixes não apresentou diferença significativa, porém apresentou efeito significativo sobre oxigênio dissolvido, turbidez, alcalinidade total e amônia. A matéria orgânica foi responsável pelos maiores valores, com exceção da turbidez, que foi menor no viveiro fertilizado com ração comercial para peixes. Entretanto, após análise de todos os parâmetros físico-químicos e microbiológicos da água dos viveiros, pode-se constatar que todos os viveiros se enquadraram nas classes II ou III da classificação de águas interiores estabelecida pelo CONAMA.

Fauna parasitária de peixes oriundos de pesque-pague do município de Guariba, São Paulo, Brasil

This study describes the occurrence and the seasonality of parasites of cultivated fish from a fee fishing farm located in Guariba, São Paulo State, Brazil (21°15'22'' S, 48°18'58'' W and 595 m of altitude), from August, 2001 to July, 2002. The presence of parasites was researched in pacu Piaractus mesopotamicus (Characidae), common carp Cyprinus carpio (Cyprinidae), nile-tilapia Oreochromis niloticus (Cichlidae), tambacu hybrid (male of P. mesopotamicus x female of tambaqui-Colossoma macropomum) and piraputanga Brycon hillari (Characidae). Results demonstrate that out of 100 fish examined, 15% were sponged for at least one of the following parasites: Trichodina sp.; monogenean helminths; copepodits of Lemaea cyprinacea; adults of L. cyprinacea; or Dolops carvalhoi. In decreasing order, the susceptibility degree of the hosts was C. carpio, P. mesopotamicus, B. hillari, tambacu hybrid and O. niloticus. In decreasing order the reported parasites were monogenean helminths, Dolops carvalhoi, Trichodina sp., adults of Lernaea cyprinacea and their young shapes.

Frequência de arraçoamento para alevinos de carpa comum

The best frequency of feeding for development of common carp fingerlings Cyprinus carpio was determined. Four hundred fish (4.88 ± 1.41 g and 6.72 ± 0.70 cm) were used, distributed in 20 tanks of 250 L each in completely randomized design with four treatments and five replicates. The four feeding strategies adopted were: providing feed once (T1), twice (T2), three (T3) and four times daily (T4) at the same amount being fractionated as described. At the end of 45 days of experiment were carried out measurements of the final weight (FW), final length (FL), weight gain (WG), feed conversion (FC), specific growth rate (SGR) and survivor (SR). It was evaluated the chemical composition of fish carcass: moisture (MT), crude protein (CP), lipids (LP) and ash (AS) and hematological analyzes performed such as erythrocyte (ER), hemoglobin (HG) and hematocrit (HT). There were significant statistical differences (P<0.01) for FW, FL, WG and SGR. For FC and SR there were no statistical differences (P>0.01). For the chemical composition the moisture, lipids and ash showed significant statistical differences (P>0.01), except only for protein (P>0.01) The hematological composition was not influenced by the feed frequency, it was not observed significant statistical difference (P>0.01) of erythrocytes, hemoglobin and hematocrit among dietary treatments. For common carp fingerlings, the provision of ration four times daily provided better final weight, final length, weight gain and specific growth rate without causing changes in the composition and hematological parameters of the fish.

Influência da biomassa inicial sobre o crescimento e a produtividade de peixes em sistema de policultivo

Analisou–se o crescimento dos peixes, a composição das espécies e a produtividade de quatro policultivos (P75, P78, P87 e P207), visando melhorar o manejo e a produtividade pesqueira dos pequenos açudes (0,1–5,0ha) do Semi–Árido brasileiro. Simulou–se as condições desses açudes em viveiros com 120 e 5.000 m² de área, sem renovação de água, utilizando moderada quantidade de adubo e fertilizante. A biomassa inicial variou de 75 a 207kg há^–1, sendo formada por: tilápia do Nilo (Oreochromis niloticus), curimatã pacu (Prochilodus argenteus), carpa comum (Cyprinus carpio), tambaqui (Colossoma macropomum) e tucunaré (Cichla ocellaris). Os peixes apresentaram baixo crescimento (< 0,01g g^–1d^–1) após 75 dias de criação (P78 e 87). O crescimento do tambaqui, da tilápia e da curimatã foi reduzido após 53 dias (P75). Em moderada biomassa, o crescimento do tambaqui foi inferior ao da carpa e da curimatã (P207). A produtividade da tilápia atingiu 720 kg ha^–1ano^–1 (P78), sendo reduzida para 220 kg ha^–1ano^–1 devido ao processo reprodutivo (P75 e P207). A produtividade da carpa de 1.600 kg ha^–1ano^–1 foi superior a dos outros peixes (P87). A biomassa inicial de 75 kg ha^–1 (60:30:4:3:3% de tilápia, tambaqui, carpa, curimatã e tucunaré, respectivamente) otimizou o crescimento e a produtividade dos peixes. A utilização de tilápias monossexadas e o fornecimento da alimentação suplementar ao tambaqui tornam–se imprescindíveis ao policultivo.

Nicho espermatogonial em Cyprinus carpio e papel do Amh na espermaogênese

Pós-graduação em Aquicultura - FCAV

List of phytoplankton, zooplankton and zoobenthos species abundances

We studied the effects of changed quality of inflow water of aquaculture ponds on three aquatic communities, phytoplankton, zooplankton and zoobenthos, during two seasons of rearing common carp (Cyprinus carpio). The new water source coming from a deep tube well was markedly different in water chemistry from the surface water sources previously used to maintain the investigated fish ponds. Ponds supplied by the tube well water were characterized by lower oxygen and water hardness, and higher total ammonia and conductivity reaching subsaline conditions. Multivariate analysis (co-inertia) revealed that all investigated groups, except Mollusca (zoobenthos), decreased in species richness, abundance and biomass due to changed water chemistry, but differed in the level of susceptibility to stressors. Assemblages of Rotifera and Cladocera were the most affected showing a sharp decline in density and number of species since 29 out of 44 species disappeared from the ponds. The abundance of Copepoda (Cyclopoida) was relatively high although significantly lower in new environmental conditions (P<0.05), with adults being more tolerant to changed inflow water than larvae. Phytoplankton, except Bacillariophyta, had a highest potential to replace previous species with newcomers more adapted to changed inflow water, providing 36 immigrant species while 49 became extinct. Although mainly influenced by fish predation, Chironomidae (zoobenthos) were undoubtedly affected by changed water chemistry, decreasing from 11 to only 3 species. These results suggest that this pattern was a result of the shift from freshwater to subsaline conditions.

The effects of density on the growth and survival of different families of juvenile Penaeus japonicus Bate

Variations in the growth and survival of six families of juvenile (initial mean weight = 4.16 g) Penaeus japonicus were examined at two densities (48 and 144 individuals m(-2)) in a controlled laboratory experiment. Survival was very high throughout the experiment (95.4%), but differed significantly between densities and rearing tanks. Family, sex and family x density interaction did not significantly affect survival. Mean specific growth rate (SGR) of the shrimp was 18% faster at the low density (1.93 +/- 0.05% day(-1)) than at high density (1.64 +/- 0.03% day(-1)). However, there was a small but significant interaction between family and density indicating that growth of the families was not consistent at both densities. The inconsistent growth of the families across the two densities resulted in a change in the relative performance (ranking) of families at each density. Sex, rearing tank and rearing cage also affected growth of the shrimp. Mean SGR of the females (1.79 +/- 0.03% day(-1)) was 5% faster than males (1.70 +/- 0.03% day(-1)) when averaged across both densities. Shrimp grew significantly faster in rearing tank 3 than rearing tank 1 or 2 at both densities. Results of the present study suggest that family x density interaction could affect the efficiency of selection for growth if shrimp stocks produced from shrimp breeding programs are to be grown across a wide range of densities. Crown Copyright (C) 2004 Published by Elsevier B.V. All rights reserved.

Endocrine-disrupting compounds: A review of their challenge to sustainable and safe water supply and water reuse

The relevance of endocrine-disrupting compounds as potential contaminants of drinking water is reviewed, particularly in the reuse of wastewater. Growing populations and increasing intensification of land and water use for industry and agriculture have increased the need to reclaim wastewater for reuse, including to supplement the drinking water supply. The variety of anthropogenic chemicals that have been identified as potential endocrine disruptors in the environment and the problems arising from their use as human and livestock pharmaceuticals, as agricultural chemicals and in industry are discussed. The potentially adverse impact of these chemicals on human health and the ecology of the natural environment are reviewed. Data for the removal of estrogenic compounds from wastewater treatment are presented, together with the comparative potencies of estrogenic compounds. The relative exposure to estrogens of women on oral contraceptives, hormone replacement therapy, and through food consumption is estimated. A brief overview of some methods available or under development for the assessment of estrogenic activity in environmental samples is provided. The review concludes with a discussion of the directions for further investigation, which include human epidemiology, methodology development, and wastewater monitoring. (C) 2006 Wiley Periodicals, Inc.

Óleo de carpa (cyprinus carpio): obtenção, refino e produção de concentração de ácidos graxos poliinsaturados

O objetivo do presente trabalho foi analisar as características e os perfis lipídicos dos óleos brutos e refinados de rejeitos de carpa comum (Cyprinus carpio), obtidos através dos processos de ensilagem ácida e termomecânico de farinha de pescado. Também foram realizados o estudo da reação de alcoólise química do óleo de carpa e obtenção de concentrados de concentrados de ácidos graxos poliinsaturados (PUFAs), através da reação de complexação com uréia. O rendimento obtido em óleo bruto para ambos os processos foi em torno de 85% em relação ao óleo presente nas vísceras de carpa. Os óleos brutos obtidos através do processo de ensilagem e do processo termomecânico apresentaram diferenças significantivas (P < 0,05) para ácidos graxos livres, índice de peróxido, valor do ácido tiobarbitúrico e cor Lovibond. Entretanto, os óleos refinados obtidos por ambos os processos não apresentaram diferença significativa para a cor Lovibond, ácidos graxos livres e valores do ácido tiobarbitúrico. Os principais ácidos graxos identificados nos óleos bruto, branqueado e refinado de vísceras de carpa foram oléico, palmítico, palmitoléico, linoléico e linolênico constituindo aproximadamente 69,6% dos ácidos graxo totais do óleo refinado. A relação ω3/ω6 foi de aproximadamente 1,05 para o óleo refinado. Assim, o óleo refinado das vísceras de carpa pode ser considerado uma rica fonte de ácidos graxos essenciais do grupo ω3 e ω6. No estudo da reação de alcoólise química e obtenção dos concentrados de ácidos graxos poliinsaturados, foi realizada a comparação de três tratamentos para reação de alcoólise variando-se a concentração molar óleo:álcool (1:21, 1:27 e 1:39). Os tratamentos apresentaram diferenças significativas para as respostas rendimento em massa de ácidos graxos livres e índice de acidez. O maior rendimento para a reação de alcoólise foi utilizando a concentração molar de 1:39 (óleo:álcool). Na fração não complexada com uréia obteve-se aumento percentual de ácidos graxos insaturados e poliinsaturados de 31,9%, redução de saturados de 75%, e aumento do conteúdo dos ácidos graxos eicosapentaenóico e docosahexaenóico (EPA+DHA) de 85,3%. A fração não complexada com uréia pode ser considerada uma rica fonte de ácidos graxos poliinsaturados e insaturados com um total de 88,9% desses ácidos graxos.

Determinação da toxicidade aguda e caracterização de risco ambiental do herbicida Roundup (glifosato) sobre três espécies de peixes

Considering their commercial importance, as these are the species of freshwater fish more commercialized in Brazil, their occurence in different kinds of aquatic environments (lakes, rivers and dams) and for being tolerant to a wide range of variation of various physical parameters and chemical water, the fish species Oreochromis niloticus, Cyprinus carpio and Colossoma macropomum were chosen for this study, furthermore, to test the toxicity we used the herbicide Roundup. The fingerlings of tilapia (Oreochromis niloticus), commun carp (Cyprinus carpio) and tambaqui (Colossoma macropomum) were submitted to the herbicide roundup in the following concentrations: 0.0 (control); 18,06; 19,10; 20,14; 21,18 and 22,22 mg.L-1, 0.0 (control); 13,89; 14,86; 15,83; 16,81 and 17,78 mg.L-1, and 0.0 (control); 18,06; 19,10; 20,14; 21,18 and 22,22 mg.L-1, respectively, three for 96 hours. The LC50 - 96h for O. niloticus, C. carpio and C. macropomum was 21,63, 15,33 and 20,06 mg.L-1 of the herbicide roundup, respectively. The results show that this herbicide is classified as slightly toxic to the three species. The values of dissolved oxygen, pH and temperature recorded in the aquarium control and aquarium experimental of the three fish species have remained without significant variations during the tests, which reduces the possibility of death caused by sudden variations of these parameters during the 96 hours the experiment. The values of LC50 between different species of fish were observed, noting that the species O.niloticus, C. carpio and C. macropomum showed no expressive differences. The values of environmental risk of Roundup were calculated to obtain more stringent parameters in assessing the dangerousness of those on nontargets. The risk of environmental contamination by Roundup for the Nile tilapia, common carp, and tambaqui are low for the lowest application rate (1 L.ha-1) and depths (1.5 and 2.0 m). The dilution of 100%, the highest recommended dose (5 L.ha-1) and depths (1.5 and 2.0 m) the risk is moderate for the three species. The values of the Risk Ratio (QR) were greater than 0,1, indicating that the values of the CAE and LC50 are above acceptable levels and there is a need, this study, a refinement in ecotoxicological tests

Survey of food network in Ovan Lake

Lake Ovan with about 9 hectares is regarded a semi-shallow lake with an average depth 5.2 meter. It is situated in Ghazvin Province, with a 1910 m high in mountainous regime. A monthly sampling was done at 3 stations studying the physicochemical and biological parameters in water and sediment at the Lake for a year. The temperature annual was measured 12.3°C and other parameters are pH as 8.8, oxygen 10, with total mean phosphate and nitrate as 0.14 & 0.8 mg/lit respectively. The chl.a mean was also measured 1.94 mg/lit. The ratio of N to P was calculated as 1:59, indicating a limiting factor for growth. Considering the trophic statues of the lake taking into account as above parameters, it is a mesotrophic lake with medium trophy. Altogether, 53 phytoplankton species were identified mostly diatoms, green algae and cyanobacteria. Although, 14 zooplankton species were identified with daphnia dominating the group. Macrobenthoses were also surveyed and 11 families were identified comprising mainly by Annelids, Gastropod, Bivalves and Insect Larvae. Other organisms were 2 dominate water plant including Phragmites australis covering at the edge of the lake and potamogeton sp in the inner parts, and also 2 fish species, common carp and Pike Perch. The diversity Shannon—Wiener index was calculated for main taxa groups with all figures lower than 3. Regarding the fish potential production of the lake based on Bramic & Lemke and morphoedophic index, it was calculated to be 20.4 kg/ha fish and a total of about 150 kg for the entire lake.