Introducing tilapia (GIFT) with shrimp (Penaues monodon) in brackishwater rice-shrimp system: impact on water quality and production

Mixed rearing of tilapia (Genetically Improved Farmed Tilapia, GIFT) with shrimp (Penaeus monodon) in brackishwater rice-shrimp system was assessed for its impact on dry season's shrimp production. The experiment was conducted in pre-selected farmer's field located at Paikgacha Upazila of Khulna district and designed with three different densities (treatment) of GIFT, viz, 0.3, 0.4 and 0.5/m² with a constant stocking density of shrimp at 3/m². Each treatment had three replications. There had a set of control treatment where GIFT was not stocked. Results of the experiment revealed that tilapia did not exert any significant effect (p>0.05) on the water quality variables, even on survival rate of shrimp (p>0.05) under farm level condition in rice-shrimp rotational system, but a density dependent negative effect (P<0.05) on the growth of shrimp led apparently lower production rate of shrimp. Though tilapia provided the major augment of total production (p<0.05) in the respective treatments than in monoculture of shrimp, but not that of the economic return. However, economic loss due to sudden shrimp crop failure might be partially minimized by the tilapia crop.

Effects of fish and prawn culture on physico-chemical parameters of water and rice yield in rice fields

An experiment was conducted with five treatments i.e. rice combined with fish having regular urea fertilization (T1), rice combined with prawn having regular urea fertilization (T2), rice combined with fish with supplementary feeding (T3), rice combined with prawn with supplementary feeding (T4) and without fish and prawn (T5) was kept as control. The dissolved oxygen values obtained in treatments with fish both in morning and afternoon were lower than the values of prawn containing treatments and control. The values of nitrate-N, ammonia-N, phosphate-P and chlorophyll-a were higher in fish containing treatments than the prawn containing treatments and control. Between the two fish containing treatments the higher gross (539.44 kg/ha) and net (440.14 kg/ha) yield were obtained in T3 with supplementary feeding and the lower gross (424.88 kg/ha) and net (314.32 kg/ha) yield were recorded in T1 without supplementary feeding. Again, between two prawn containing treatments the higher gross (108.69 kg/ha) and net (81.92 kg/ha) yield were obtained in T4 with supplementary feeding and lower gross (64.32 kg/ha) and net (30.98 kg/ha) yield were recorded in T2 without supplementary feeding. The highest yield of rice grain (3.45 mt/ha) and straw (6.37 mt/ha) were obtained in T1 with fish having urea fertilization without feeding.

The comparison of inhibitory effects of barley and rice straws to control of algae and aquatic weeds in fish ponds

Bioassays were carried out to consider the relative effect of barley and rice straw extracts on the growth of 12 problematic freshwater algae. The laboratory results demonstrated that growth of Microcystis aeruginosa; Aphanizomenon flos–aquae, Anabaena flos–aquae, Synura petersenii, and Dinobryon sertularia were all inhibited, whereas Oscillatoria tenuis, Asterionella formosa, Spirogyra sp., and Hydrodictyon reticulatum grown were stimulated by the barley straw extract. No significant effect was also found on the growth of Chlorella kessleri, Scenedesmus subspicatus, and Navicula pelliculosa.

Generation, flow and utilisation of information on the regional fish trade

The purpose of the study was to provide an in-depth understanding of information generation, flow and utilization within Uganda’s regional fish trade. The study was carried out at district headquarters, border points, landing sites and border markets, involving DFOs, Customs Officials, BMU executives and market managers.

Perspectives of impacts of international fish trade in Kenya

There has been tremendous growth in international trade on fish and fisheries products in the last four decades. In 1970 the value of internationally traded fish was estimated at 3 billion; this increased to US$ 15 billion in 1980, US$ 36 billion in 1990 and US$ 55 billion in 2000 (Ahmed, 2003). Recent statistics show that fish trade has surpassed other agricultural commodities that have traditionally been traded internationally such as coffee, tea, cocoa, sugar, cereals, meat, oils and milk. In 2000, fish contributed 22% of the value of all agricultural exports, making it the highest internationally traded food product (Ahmed, 2003). In another perspective, nearly 40% of the world's fish is now sold in the international market. The flow of fish in the international market is highly lopsided. About 50% of fish exportscomefromthedevelopingworld ,ofwhich 20%arefrom low-incomefood deficient countries. Most of this fish, however, is consumed by the developed countries, which account for nearly 80% of all imported fish. The EU, USA and Japan are the major importers, accounting for over 77% of global fish imports. Thus, while developing countries playa big role in fish production , they consume very little of it, instead preferring to sell for the hard currency. In some fish exporting countries, especially those in Asia, there is some link between fish exports and imports of substitute and complementary foods. Much of the increased earning from fish exports in those countries is explained by a corresponding rise in expenditure on imported foods. This is not the case in many of the fish exporter nations in Africa. In their case, fish exports generate foreign exchange that they use to meet other socio-political objectives; hardly is it aimed at solving the wider food needs. Therefore, one of the most immediate concerns of international fish trade is its impact on food security in the poor exporter nations.

The potential of community fish refuges (CFRs) in rice field agro-ecosystems for improving food and nutrition security in the Tonle Sap region

The fisheries sector in Cambodia contributes 8%–12% to national GDP and 25% - 30% to agricultural GDP, with an estimated 4.5 million people involved in fishing and associated trades. Fish and other aquatic animals are important food sources, contributing an estimated national average of 60% - 70% of total animal protein intake. Of the 2013 total fish production, 550,000 metric tons were harvested from freshwater habitats, of which rice field fisheries and small-scale family fisheries contributed approximately 20%. The productivity and value of rice field fisheries to households in rural Cambodia has been highlighted in a number of previous studies. The Fisheries Administration of the Ministry of Agriculture, Forestry and Fisheries plans to increase productivity from rice field fisheries and aquaculture at an annual rate of 15% to maintain supply for a growing population. This report draws mainly on the baseline and monitoring data from the Rice Field Fisheries Enhancement Project (RFFEP) during its implementation between 2012 and 2014. Reference is also made to the Fish on Farms project to highlight the relative contribution of fish from small-scale aquaculture compared to wild-caught fish.

Product life trade-offs: what if products fail early?

Increasing product life allows the embodied emissions in products to be spread across a longer period but can mean that opportunities to improve use-phase efficiency are foregone. In this paper, a model that evaluates this trade-off is presented and used to estimate the optimal product life for a range of metal-intensive products. Two strategies that have potential to save emissions are explored: (1) adding extra embodied emissions to make products more sturdy, increasing product life, and (2) increasing frequency of use, causing early product failure to take advantage of improvements in use-phase efficiency. These strategies are evaluated for two specific case studies (long-life washing machines and more frequent use of vehicles through car clubs) and for a range of embodied and use-phase intensive products under different use-phase improvement rate assumptions. Particular emphasis is placed on the fact that products often fail neither at their design life nor at their optimal life. Policy recommendations are then made regarding the targeting of these strategies according to product characteristics and the timing of typical product failure relative to optimal product life.

Design trade-offs for energy regeneration and control in vehicle suspensions

This paper investigates the fundamental trade-offs involved in designing energy-regenerative suspensions, in particular, focusing on efficiency of power extraction and its effect on vehicle dynamics and control. It is shown that typical regenerative devices making use of linear-to-rotational elements can be modelled as a parallel arrangement of an inerter and a dissipative admittance. Taking account of typical adjustable parameters of the generator, it is shown, for a given suspension damping coefficient, that the power efficiency ratio scales with inertance. For a typical passenger vehicle, it is shown that there is a feasible compromise, namely that good efficiency is achievable with an inertance value that is not detrimental to vehicle performance. A prototype is designed and tested with a resistive termination and experimental results show good agreement between ideal and experimental admittances. The possibility to use dynamic (rather than purely resistive) loads to improve vehicle control without limiting the energy recovery is discussed. © 2013 Copyright Taylor and Francis Group, LLC.

Isolation and characterization of polymorphic microsatellites in a sex-reversal fish, rice field eel (Monopterus albus)

The rice field eel (Monopterus albus) is a fish of economic importance in China and some Asian countries. From a (GT)(n)-enriched genomic library, 30 microsatellites were developed by employing the fast isolation by AFLP of sequences containing repeats (FIASCO) protocol. Thirteen loci exhibited polymorphism with two to 13 alleles (mean 7.9 alleles/locus) in a test population and observed heterozygosity ranged from 0.3125 to 0.9688 (mean 0.7140). These loci should provide sufficient level of genetic variation to study the fine-scale population structure and reproductive ecology of the species.