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1.
Lateral migration of fishes in Amazon floodplains 总被引:2,自引:2,他引:2
C. C. Fernandes 《Ecology of Freshwater Fish》1997,6(1):36-44
Abstract— Migrations of fish in the outlet channel of Lago do Rei, a floodplain lake on Careiro Island in the Amazon River, were examined using three capture methods. Of the 85 species found in the Parana do Rei (channel), 20 migrated between the lake and river. Migrations from the lake to the river occurred in two pulses. In August-September, as the river water level began to recede, some fish migrated to the river with the current. As the river water level rose in December-January, additional fish migrated towards the main river against the current. Fish returned to the lake by March or April after they had spawned. The migratory patterns of six species, family Curimatidae and Prochilodontidae: Potamorhina latior, Psectrogaster amazonica , P. rutiloides, Curimata kneri, Prochilodus nigricans and Semaprochilodus taeniurus are described in detail. Lateral migrations of fish in this ecosystem appear to be closely linked to breeding and to physical habitat changes related to river water level. 相似文献
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Abstract The present study analyses temporal trends in the characteristics of the artisanal fleet landing at ports in the city of Santarém (lower Amazon) from 1993 to 2003. A total of 2714 boats visited the city, accounting for more than 76 000 landings. Of these, 1952 were fishing boats; the others were buyer boats, specialised in the purchase of fish in rural areas for resale in Santarém. The activity involves more than 13 000 fishermen. Fishing boats are made of wood, are on average 11 m long and powered by a 20 hp outboard motor. Boats operate with an average of six to seven fishermen, spending 6 days per trip and catching between 300 and 800 kg of fish. Most variability in yield can be explained by the ice consumed (70%), the number of fishermen trip−1 (19%), fuel consumed (4%) and days spent fishing (3%). The yield changed according to the size, origin and type of boat. Fishing boats coming from more distant locations, in the state of Amazonas, performed better than those from Santarém. Total yield declined slightly during the study period. Mean age of fishing boats and fishing power is increasing. Consumption of ice and fuel by trip, number of fishermen trip−1 and mean days fishing showed positive trends. Financial subsidies from governmental agencies are criticised. Fleet performance and management options are discussed. 相似文献
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Abstract Co-management agreements, whereby community rules for the management of local floodplain lake fisheries are legalised and enforced by the government, have become common in the lower Amazon. Agreements are intended to limit exploitation, in particular by commercial boats, to raise stock abundance and fisheries productivity for the benefit of local subsistence-oriented fishers and for conservation. A spatially replicated observational study was carried out to evaluate the performance of fishing agreements in terms of perceived rule compliance and actual impacts on fishing activities, catch and catch per unit of effort (CPUE, a measure of fisheries productivity and proxy for stock abundance). Perceived rule compliance was high, and this was corroborated by observed changes in fishing practices. Catch per unit of effort was significantly higher (by 48% on average) in areas subject to fishing agreements than in control areas without. Most likely this effect was attributable to the effective exclusion of mobile commercial fishing boats. Household fishing effort and catch in local communities were not significantly affected by the agreements, although a tendency towards slightly higher catches at lower effort was noticeable. In conclusion, the co-management agreements have led to greater local control over resources and brought significant productivity and conservation benefits. 相似文献
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V. S. Batista J. C. Alonso R. J. Ladle N. N. Fabré 《Fisheries Management and Ecology》2018,25(2):116-126
Artisanal fishers of the upper reaches of the Amazon River use a variety of tactics to catch giant Brachyplatystoma catfish species: Brachyplatystoma vaillantii Valenciennes, Brachyplatystoma rouseauxii (Castelnau) and Brachyplatystoma filamentosum (Lichtenstein). These catfish are migratory, caught with different gears, by different communities, and influenced by temporal and spatial changes in river conditions. Facing these factors, it was hypothesised that the catfish fishery yields in the headwaters of the Amazon are determined by fishing tactics efficiency, riverscape features and governance basis. Data on catfish yields were collected from two contrasting riverscapes (rapids and floodplains) in the most important Amazonian affluent in Colombia—the Caquetá River. Results indicated that: (1) catfish yield was strongly associated with fishing effort in both riverscapes, (2) seasonal drivers play an essential influence in the high rapids reach, and river level in the low floodplain reach, (3) community strategies affected yield, although the effect is different depending on the gear used as the environment profile affects enforcement. Based on the results, it was concluded that efficient upstream management of these species should combine specific measures for each riverscape with an integrated approach to the river production system that considers catfishes longitudinal migrations and the growth overfishing occurring in the Amazon estuary. 相似文献
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This study characterizes the fishermen and the commercial fishing fleet of the lower Amazon, based on data collected from 5446 boats operating out of the city of Santarém in 1997. An economic analysis of the activities of these boats was based on 50 interviews with boat operators. Larger and smaller boats use essentially the same technology, but there are significant differences in fishing strategies. Smaller boats supply local markets and their catch consists of a large variety of fish species. Larger boats tend to specialize in a small number of catfish species, and supply fish processing plants. Smaller boats are less efficient in terms of catch per unit effort (CPUE) (kg fisherman–1 day–1 ), but are more efficient economically, earning more for each unit of capital invested than larger boats. Most boats operating from Santarém have a storage capacity of <4 t. Boats in this size (0<4 t) account for 87% of the total fleet direct employment, and 73% of total income. Thus despite the lack of attention from regional policy makers, these smaller boats are an important source of food, income and employment in the lower Amazon region. 相似文献
6.
Effects of different variable sets on the potential distribution of fish species in the Amazon Basin
Facundo Alvarez Pedro Gerhard Daniel Paiva Silva Bruno Spacek Godoy Luciano Fogaça de Assis Montag 《Ecology of Freshwater Fish》2020,29(4):764-778
Estimating species’ potential distribution is one of the main objectives of macroecology, especially when sampling biases can affect knowledge on how environmental variables affect species distribution. Ecological niche models estimate species’ environmental niches from different variables and their occurrences. Using the presence-only data from eight Amazonian fish species, which inhabit rivers and streams, we aimed to (a) explore the effect of different sets variables on the spatial distributions of target species and (b) evaluate the predictive responses of MaxEnt to sets of variables with different degrees of complexity. MaxEnt has high flexibility in relation to the input data and its performance is influenced by a moderate number of adjustable parameters, allowing for high precision results when balancing underestimation and overestimation errors. We used environmental predictors in MaxEnt the principal components of climatic, topographic and edaphic variables as inputs. The combination of topographic and edaphic variables produced more precise and spatially restricted distribution ranges for all species when compared to those generated with climatic variables. All models reached high AUC values, especially for stream species. Modelled range sizes were broader for the river species, suggesting different tolerance thresholds and habitat preferences when compared to stream species. The complexity of the different variables sets did not affect MaxEnt's prediction capacity. However, for stream species, MaxEnt showed a greater predictive power. This work increases the knowledge with regards to the influence of different environmental predictors on the spatial patterns of the distribution of Amazonian fish. 相似文献
7.
Characterization of the fishery in river communities in the low-Solimões/high-Amazon region 总被引:1,自引:0,他引:1
V. S. BATISTA A. J. INHAMUNS C. E. C. FREITAS D. FREIRE-BRASIL 《Fisheries Management and Ecology》1998,5(5):419-435
Questionnaires were used to collect data from the low-Solimões/high-Amazon region, Brazil, between December 1992 and February 1994. Gillnets, fishing rods and castnets were the preferred gear used. Gillnets were used throughout the year whilst other gears were used only in certain periods of the year. The fish caught tended to supply family needs but a high proportion were sold in regional markets. Curimatã (Prochilodus nigricans), pacu (various Myleinae) and ruelo (young Colossoma macropomum) were the most frequent species caught. Around 50% of the fish caught in these fisheries was consumed fresh, and the remainder was stored under ice or salted. Fish is the most important source of animal protein for this region, with an annual mean consumption rate of 550 g capita?1 day?1. The fishery has changed from a subsistence to a commercial scale, which was associated with increasing cattle ranching activities. This may have serious social and economic implications. 相似文献
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Roselien Crab Yoram Avnimelech Tom Defoirdt Peter Bossier Willy Verstraete 《Aquaculture (Amsterdam, Netherlands)》2007,270(1-4):1-14
As the aquaculture industry intensively develops, its environmental impact increases. Discharges from aquaculture deteriorate the receiving environment and the need for fishmeal and fish oil for fish feed production increases. Rotating biological contactors, trickling filters, bead filters and fluidized sand biofilters are conventionally used in intensive aquaculture systems to remove nitrogen from culture water. Besides these conventional water treatment systems, there are other possible modi operandi to recycle aquaculture water and simultaneously produce fish feed. These double-purpose techniques are the periphyton treatment technique, which is applicable to extensive systems, and the proteinaceous bio-flocs technology, which can be used in extensive as well as in intensive systems. In addition to maintenance of good water quality, both techniques provide an inexpensive feed source and a higher efficiency of nutrient conversion of feed. The bio-flocs technology has the advantage over the other techniques that it is relatively inexpensive; this makes it an economically viable approach for sustainable aquaculture. 相似文献
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A. C. B. OLIVEIRA L. A. MARTINELLI & M. Z. MOREIRA M. G. M. SOARES & J. E. P. CYRINO 《Fisheries Management and Ecology》2006,13(3):135-142
Abstract Stomach content and stable isotopes of tambaqui, Colossoma macropomum (Cuvier), were use to determine seasonality of energy sources in a floodplain lake in the central Amazon. The turnover time of carbon in young tambaqui was fast enough to detect a broad seasonal variation both in stomach content and tissue isotopic signal of carbon and nitrogen. The relative importance of food items varied with water level. C3 plants (seeds and fruits) contributed between 55% and 95% of the biomass fraction of tambaqui. Zooplankton contributed a minimum of 26% of the nitrogen fraction during periods of flooding, and a maximum of 67% in the dry season. C4 plants (macrophyte leaves and roots) contributed a maximum of 26% of the biomass fraction and 13% of the N fraction mainly during the flooding period. The feeding habits and behaviour of tambaqui are complex and linked to the flood pulse. 相似文献
11.
Leandro Castello Laura L Hess Ram Thapa David G McGrath Caroline C Arantes Vivian F Renó Victoria J Isaac 《Fish and Fisheries》2018,19(3):431-440
Inland fisheries underpin food security in many tropical countries. The most productive inland fisheries in tropical and subtropical developing countries occur in large river–floodplain systems that are often impacted by land cover changes. However, few studies to date have assessed the effects of changes in floodplain land cover on fishery yields. Here, we integrated fisheries and satellite‐mapped habitat data to evaluate the effects of floodplain deforestation on fishery yields in 68 floodplain lake systems of the lower Amazon River, representing a wide range in relative amounts of woody, herbaceous and non‐vegetated land cover. We modelled relative fish yields (fish capture per unit effort [CPUE]) in the floodplain lakes as a function of the relative amounts of forest, shrub, aquatic macrophyte and bare/herbaceous habitats surrounding them. We found that forest amount was positively related (p = .0003) to multispecies CPUE. The validity of these findings was supported by rejection of plausible alternative causative mechanisms involving habitat‐related differences in amount of piscivores, fishing effort, lake area, and habitat effects on CPUE of the nine taxa dominating multispecies yields. Our results provide support to the idea that removal of floodplain forests reduces fishery yields per unit effort. Increased protection of floodplain forests is necessary to maintain the food, income and livelihood security services provided by large river–floodplain fisheries. 相似文献
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R. G. Leite C. A. R. M. Araújo-Lima R. L. Victoria L. A. Martinelli 《Ecology of Freshwater Fish》2002,11(1):56-63
Abstract – Aquatic macrophytes form the most productive habitat of the Amazon floodplain and account for more than 60% of the net primary production of the ecosystem. Aquatic grasses are the dominant macrophytes and the main feeding ground of Amazonian larval fish. The present study used stable isotopes of nitrogen and carbon to measure the contribution of aquatic grasses to the production of eight larval fish, and describes the structure of the trophic chain. The carnivore larvae were at the third trophic level, and the detritivores were at the second and third trophic levels. The contribution of aquatic grasses to larval fish production was variable. It could reach a mean value of 25% for three species, but its contribution probably did not exceed 12% in the other five species. 相似文献
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The aim of this study was to evaluate the effects of hatchery‐tank colours (white, yellow, red, blue, green and black) on the performance of larval culture of Macrobrachium amazonicum. The larvae were fed daily with newly hatched Artemia nauplii. The hatchery‐tank colours affected the light level inside the tanks, the consumption of Artemia nauplii (AN), larval development, survival, mass gain and productivity of postlarvae (PL). The overall consumption of Artemia nauplii per larva during the larval cycle was 30% and 45% higher in the green and red tanks respectively. The significant variation of AN consumption among tank colours (P = 0.0006) indicates that M. amazonicum larvae are visual predators. Survival was higher in the black, blue and green tanks, reaching more than 75%. However, the highest productivity was obtained in the black tanks (80.1 PL L?1). Lighter coloured tanks and excess luminosity (more than 2 μmol s?1 m2 at tank bottom) appear to be important stress factors for larvae, contributing to reduce survival and productivity. The results indicate that rearing M. amazonicum in black tanks will improve larvae condition, ensure greater productivity of postlarvae and lower Artemia consumption, increasing technological and economic viability. 相似文献
16.
《渔业法》经修订后,在养殖业一章中增加了一条:“县级以上地方人民政府在核发养殖证时,应当优先安排当地的渔业生产者。”这是在我国养殖业已超过捕捞业成为我国渔业发展的主要增长点以及我国压缩海洋近海捕捞力量以后,面临渔业产业结构调整,将有大批的渔业生产者从捕捞业转移到其他产业的情况下,保障渔民的权益而引入的一项重要举措。在国家鼓励渔业发展的政策下,我国的渔业迅速发展,但是,由于自然资源变化和国际海洋新秩序形成,我国渔民不可避免地面临一场空前的产业调整。1999年开始,我国对捕捞业实施了零增长的产业政策,不… 相似文献
17.
Marcelo F. da Silva Rebeca S. de Araújo Diehgo T. da Silva Osimar Sanches Igor Hamoy Edilson Matos 《Journal of fish diseases》2019,42(6):905-912
Ninety‐seven specimens of spotfin hatchetfish, Thoracocharax stellatus, an ornamental freshwater species from the Amazon basin, were captured in the basin of the Guamá River in the municipality of Belém, in northern Brazil, and analysed for coccidiosis infection. Overall, 26 of the specimens were infected by apicomplexan parasites of the genus Goussia, with unsporulated forms being found in the gastric epithelium and sporulated forms in the intestinal lumen. The spheroid oocysts (mean diameter: 13.2 ± 1.7 μm) have four elliptical sporocysts. A partial sequence of the SSU rDNA of the new species was obtained, which contained 1,121 base pairs, with 43.8% guanine + cytosine (G + C), and the bases distributed as follows: A = 28.1%, C = 18.3%, G = 25.5% and T = 28.1%. The combined analysis of the morphometric and phylogenetic evidence confirmed that the specimens represented the genus Goussia and were allocated to a new species, Goussia guamaensis n. sp., which is described here. 相似文献
18.
Roselene Nogueira Rodrigues Marcos Sidney Brito Oliveira Marcos Tavares-Dias 《Journal Of Applied Aquaculture》2018,30(1):29-38
Fish farming has grown rapidly in Brazil over the last two decades, due in part to the availability of water and species with potential for cultivation, such as Colossoma macropomum. This farmed fish, however, can be affected by parasitic infections with high mortality rates (>35%). The main objective of the present study was to describe the first occurrence of the Trypanosoma species in Colossoma macropomum, which occurred in fish cultured in the Brazilian Amazon region, as well as to morphologically characterize the trypomastigotes and the impact of these hemoparasites on the body condition of the hosts. The trypanosomes found in the blood of Colossoma macropomum were morphologically characterized by the size of the trypomastigote form, indicating the presence of only one morphotype. Of the 39 hosts examined from one fish farming, 41.0% were infected by Trypanosoma sp., with low levels of infection (mean blood density of 3.7/μL). The condition factor of the asymptomatic hosts was not affected by hemoparasitism. There was no correlation between the abundance of Trypanosoma sp. and the condition factor and size of the hosts. Finally, our understanding of host-parasite interactions and the detection of emerging diseases are fundamental for aquaculture. 相似文献
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Danilo G. R. Castanho Cláudia P. de Deus Jansen Zuanon Sergio Santorelli Rafael P. Leitão Fabrício B. Teresa 《Ecology of Freshwater Fish》2020,29(4):533-541
The consequences of over-exploitation may seriously impair the integrity and functioning of ecosystems. When loss of species is accompanied by the loss of ecological processes, the effects are no longer just taxonomic and may affect the stability of the environments. Ornamental fishing is one of the main economic activities of the middle Negro River. Such activity is directed to a small number of species and has the Cardinal Tetra (Paracheirodon axelrodi) as the main target species. Given the potential effects this pressure and the lack of information on its consequences, the present study analysed, through simulations, the possible effects of depletion of ornamental fish populations on the functional structure of fish assemblages, represented by functional diversity (FD) and functional redundancy (FR) indexes. We sampled 13 streams exploited by the ornamental fishery, where we collected 4,286 specimens of 110 species, of which 22 were targeted as ornamental fishing. We found that the ornamental species corresponded, on average, to 27.8% of the species and 33.3% of the FD of the assemblages. In a scenario of complete exclusion of ornamental species, local communities would lose 24.6% of the FD and reduce up to 12% of the FR. With these results, it is possible to infer that the local extinction of exploited species would cause negative impacts on the multifunctionality and the resilience of the streams ecosystems. In this way, we emphasise the need for proper management of the ornamental fisheries aiming to the sustainability of the activity and to the conservation of ecosystem functionality. 相似文献