Measuring technical,allocative and cost efficiency of pangas (Pangasius hypophthalmus: Sauvage 1878) fish farmers of Bangladesh

The present study is conducted to measure the technical (TE), allocative (AE) and cost efficiency (CE) of pangas fish‐producing farmers of Bangladesh. Data envelopment analysis is used to measure the efficiency while Tobit regression is applied to identify the factors affecting efficiencies. The estimated mean TE, AE and CEs are 86%, 62% and 54% respectively. Pangas production is characterized by considerable technical inefficiencies and substantial allocative and cost inefficiencies. Pond size, fingerling size, culture length and use of pelleted feed are important determinants of efficiencies. It is nevertheless profitable in terms of benefit–cost ratio, break‐even yield and price criteria. Production of pangas can be made further profitable by eliminating inefficiencies. Proper mixing of inputs given their prices could make pangas producers profit maximizers. Efficiency improvement is expected to help to increase production and provide scopes for exporting the surplus production. More fisheries extension is suggested to expand pangas culture and improve efficiency.     

Biochemical impacts of salinity on the catfish,Heteropneustes fossilis (Bloch, 1794), and possibility of their farming at low saline water

Although a stenohaline freshwater fish, the stinging catfish Heteropneustes fossilis, is also available in the freshwater fringes of the coastal areas of Bangladesh, the tolerance of this species to variable environmental salinity has not been thoroughly investigated. Based on median lethal salinity (MLS‐50 96 h), three sublethal salinity levels (3 ppt, 6 ppt and 9 ppt) and a control (0 ppt), each with three replications were selected to observe the effects of mildly brackish conditions on the fish for a period of 90‐day exposure. Better growth and survival were found up to 6 ppt compared with control. Salinity more than 6 ppt appeared unsuitable for H. fossilis fingerling due to increased mortality and reduced growth. To determine biochemical alterations, a few important physiological parameters were observed after 90 days of exposure. Glycogen level of liver and muscle in the fish reared at 9 ppt salinity decreased significantly (P < 0.05) as compared to the control. Glucose level in blood and liver was also found to be increased in fish with increase in salinity. ALP and ATPase activities were reduced significantly in both muscle and liver tissues at higher salinity, indicating the stress mitigation effect. However, all the biochemical parameters were found in normal condition up to 6 ppt compared with control. This evidence suggests that H. fossilis can sustain and grow well below 6 ppt and can be a potential candidate for culture in coastal areas after heavy downpour when the salinities level falls to 6 ppt or lower.     

Agglomeration externalities and technical efficiency: An empirical application to the pond aquaculture of Pangas and Tilapia in Bangladesh

This article analyzes the effects of agglomeration externalities on productivity and efficiency by applying a stochastic production frontier model with a technical inefficiency model to the aquaculture industry. Agglomeration externalities refer to the costs and benefits to firms from clustering. Agglomeration studies within aquaculture have focused on the intensive salmon industry, whereas this study focuses on low-technology, extensive pond aquaculture, representing most farmers in the developing world and using Bangladesh as an empirical case. The results show that there is a positive externality effect of regional industry size on the production possibility frontier and a negative effect on technical efficiency. Farm density enhances efficiency and the farm proximity to output markets decreases efficiency. Thus, policies aimed at increasing aquaculture pond production in developing countries should consider farm locations and their access to input and output markets, all of which affect farm productivity and efficiency.     

孟加拉国杂交水稻发展现状及探讨

介绍了孟加拉国杂交水稻的发展现状,分析了当地杂交水稻本土化制种和市场发展中存在的主要问题,提出了相应发展对策,为下一步市场开拓提供参考。     

Slow,small and shared voluntary relocations: Learning from the experience of migrants living on the urban fringes of Khulna,Bangladesh

The paper conceptualises the process of voluntary relocation undertaken by rural farmers to informal settlements in coastal cities. These are journeys that occur without formal institutional support, utilising migrants' own agency. Learning from these community‐driven relocations has merit in rethinking climate change adaptation at the regional level. In this paper we present stories of 17 families who have progressively relocated to the fringes of Khulna city in southwestern Bangladesh. We observe three key attributes: first, relocations are slow, neither singular nor immediately completed, but rather take months of careful back and forth journeys of family members between their places of origin and destination. Second, relocations rely on small networks of relatives and acquaintances at the destination. Third, relocations are built on shared responsibilities distributed among a range of actors in places of origin and destination. We conclude that these slow, small and shared relocations are likely to be realised as forms of ongoing adaptation by rural farmers if their aspirational mobilities, social relations and supports are maintained at a regional scale. This kind of migration as adaptation may bring about just outcomes for those displaced without necessarily promoting rigid planning interventions that tend to fix resettlement solutions in place and time.     

Impacts of hydraulic engineering on the dynamics and production potential of floodplain fish populations in Bangladesh

Abstract The present paper examines the impact of hydraulic engineering on fish production potential in Bangladesh by comparing the population dynamics of six species sampled from floodplains inside and outside the Pabna Irrigation and Rural Development Project (PIRDP) during 1995 and 1996. All the sampled populations were dominated by a single cohort for most of the year. Recruitment occurred both inside and outside the flood control scheme, coinciding with floodplain inundation. The growth of all the six species was rapid and strongly seasonal, and all species reached sexual maturity by the end of their first year. With only one exception, growth rates, condition and fecundity were either significantly higher inside the scheme, or not significantly different between the two sampling locations. Differences in growth performance were explained by fish density. No significant differences between sampling locations were detected in the length at maturity (Lm₅₀), spawning period or instantaneous total mortality rate (Z). Estimates of Z were very high for all six species ranging from Z = 3.2 year^?1 to Z = 4.7 year^?1, equivalent to only 4% and 1% survival year^?1, respectively. It was concluded that the production potential of individual fish is at least as high inside as outside the PIRDP and that the 38–51% lower yields per unit area recorded inside the scheme reflect its partial inaccessibility to migrant species.     

Local expert experiences and perceptions of environmentally induced migration from Bangladesh to India

This study investigates local expert perceptions of the role of environmental factors, especially in terms of contemporary climate change, in population movements from Bangladesh to India. The aim is to delve into locally held understandings of the phenomenon and to gain a better understanding of these migration processes, which are actively intertwined with local experiences. Both Indian and Bangladeshi experts were interviewed using semi‐structured, in‐depth interviews in order to explore insights from locally held perceptions and understandings of contextual factors. In total, 10 Bangladeshi and 15 Indian experts were interviewed, covering different disciplines, sectors, regions and job types, together providing a more complete and grounded picture of views of environmentally induced migration in Bangladesh and India. The results show that climate change is perceived by local experts as one of the key factors influencing migration in Bangladesh, both internally and externally. The interviewees, however, placed environmentally induced migration in a broader context of labour and economic migration. In particular, migration for environmental reasons in Bangladesh was evident long before the emergence of climate change as an issue. According to the interviewed experts, this does not preclude increased environmentally induced migration within and from Bangladesh in the future, but its analyses ought to be placed in historical and economical contexts.     

Evaluation of freshwater prawn‐small fish culture concurrently with rice in Bangladesh

An integrated aquaculture of freshwater prawn (Macrobrachium rosenbergii) and self‐recruiting small fish mola (Amblypharyngodon mola) was conducted in farmers' rice fields at Mymensingh, Bangladesh. There were four treatments with three replications. Four stocking densities, 10 000, 15 000, 20 000 and 25 000 ha^?1, of freshwater prawn were applied. The stocking density of mola was the same (20 000 ha^?1) in all treatments. During land preparation, triple super phosphate (TSP) and murate of potash (MP) were applied at the rate of 150 and 75 kg ha^?1 respectively. Urea was applied at the rate of 200 kg ha^?1 in equally distributed three installments after 16, 45 and 65 days of rice plantation. Prawns were fed with commercial pelleted feed at 3–8% body weight. All water quality parameters were found to be within the suitable range for freshwater prawn culture. There was a homogenous abundance of plankton communities in all treatments. The results of a 4‐month culture period showed that the average production of prawn ranged from 222 to 388 kg ha^?1, mola 51 to 68 kg ha^?1 and rice 2 880 to 3 710 kg ha^?1. Significantly higher production of both prawn and mola was recorded in the plots where the freshwater prawn stocking density was 15 000 ha^?1. This treatment resulted in a net profit of USD 1100 ha^?1.     

Frost Susceptibility of Five Almond [Prunus dulcis (mill.) D.A. Webb] Cultivars Grown in North-Eastern Morocco as Revealed by Chlorophyll Fluorescence

Almond [Prunus dulcis (Mill.) D.A. Webb] is one of the most important nut crops worldwide. It requires chilling during winter to break dormancy and develop fruiting buds. However, late winter chilling and early spring frosts may damage the reproductive tissues leading to productivity reduction. In the present work, we evaluated the frost susceptibility by means of chlorophyll fluorescence in flower buds of almonds cultivated in two different sites in Morocco: Aknoul in the north and Sidi Bouhria in the east. Five widely grown almond cultivars, namely Marcona, Fournat de Brézenaud, Ferragnès, Ferraduel, and Tuono, were involved in this study. Flower buds were incubated in temperatures of –3, –2, –1, 0, and 25 °C during 24 h and thereafter the Fv/Fm ratio was measured at the ovary zone. Combined analysis of variance showed that cultivar was the major source of variability, while site and cultivar by site interaction effects were of lesser extent and explained together less than 20%. At 25 °C, all cultivars displayed higher scores of Fv/Fm ratio. By decreasing temperature of incubation, this ratio decreased proportionally. Kinetics of chlorophyll fluorescence in response to the frost treatment followed two patterns: A linear decrease translated by frost susceptibility for late-flowering cultivars Ferragnès and Ferraduel, and quadratic curve with an inflection point at –1 °C indicating a chilling tolerance for Tuono and the early-flowering cultivars Marcona and Fournat de Brézenaud. However, Ferragnès and Ferraduel (with later flowering date) are not likely to be affected by low temperatures at the end of spring when there is no risk of frost.     

东北三省生态占用动态变化分析

运用生态足迹方法中的不变产量法和可变产量法,考察了东北三省自1978年以来生态占用的动态变化。研究结果表明:东北三省生态占用呈上升趋势,生态环境压力持续增大,但土地单产的提高对于降低生态占用、减轻环境压力具有重要意义,可以有效地减缓生态占用快速上升的势头,但是林地的生产能力提高较慢。