|Understanding the role of feed in shrimp ponds and matching natural and supplemental feeds for sustainable shrimp production
Kabir, K.A. ; Verdegem, M.C.J. ; Schrama, J.W. ; Karim, M. ; Philips, M. ; Verreth, J.A.J. - \ 2016
The central hypothesis of this research is that the dietary requirements of shrimp are influenced by culture system and culture intensity. In outdoor ponds, nutrients in formulated feed can be eaten by the shrimp directly or indirectly, the latter by eating biota present in the water column or benthic community which incorporated waste nutrients. An integration of outdoor compartmentalized ponds and indoor tanks was designed to quantify the contribution of different routes (directly eaten, water column or bentic) to shrimp production in ponds. From the feed composition point of view it was assumed that DP:DE, fat:carbohydrate and NSP:starch ratio of a diet has major influences on the above mentioned feeding routes. A preliminary experiment was executed using two diets differing in DP:DE ratio and three feeding levels: 0, 45 and 90% of recommended intensive feeding level. The feeding routes were tested outdoor (ponds; 6 replicates) and indoor (tanks; 3 replicates) over a two months period, stocking 20 juvenile shrimp m-2. Shrimp growth was higher in the ponds while survival was higher in the tanks (P < 0.05). The DP:DE ratio of the diets did not affect growth and survival, except that calcium deposition was better with the high DP:DE ratio diet. In ponds, shrimp growth and survival was similar for the 45% and 90% feeding levels, and were better than with the 0% feeding level in terms of individual growth 47%, survival 47% and biomass growth m-2 350%. Among the 45% and 90% feeding level survival, individual growth and biomass growth m-2 was better in 45% feeding in both ponds and tanks. Concentrations of chlorophyll a, phytoplankton, zooplankton, benthos and total bacterial count in both water column and sediment declined gradually between the start and end of the experiment. The unexpected low response to changes in the DP:DE ratio might have been caused by a reduction in salinity due to heavy rain from 5 ppt at the start to 1 ppt at the end of the experiment. Measurements of gut fullness showed the shrimp consumed feed and natural food. Availability of the latter through the water and benthic routes declined with increase in shrimp biomass in the system. In spite of high consumption, the energy intake might have been too low for osmoregulation at these low salinity rearing conditions, limiting feed utilization efficiency. P. monodon is known to perform best at salinities above 20 ppt. Additional information from a follow up experiment executed at a salinity > 20 ppt is needed to fully explain experimental results.
Enhancing benefits from polycultures including tilapia (Oreochromis niloticus) within integrated pond-dike systems: A participatory trial with households of varying socio-economic level in rural and peri-urban areas of Bangladesh
Karim, M. ; Little, D.C. ; Verdegem, M.C.J. ; Telfer, T. ; Wahab, M.A. - \ 2011
Aquaculture 314 (2011)1-4. - ISSN 0044-8486 - p. 225 - 235.
resource-poor farmers - farming systems - aquaculture - fertilization - diversity - thailand - issues - nile
Linkages between the fish ponds and surrounding land for horticulture are a distinctive feature of farming households in Bangladesh. It was hypothesised that integration of fish ponds in integrated farming system enhances livelihoods and reduces poverty. The effects of introducing tilapia into existing integrated farming systems on the broader pond-dike system and associated livelihoods in rural and peri-urban settlements in central north (Mymensingh District) of Bangladesh were evaluated. Farmer participatory research carried out during June 2004 to March 2005 showed that production of fish could be substantially increased by increasing nutrient inputs rather than by stocking tilapia as an additional species. However, the ‘improved’ nutrient input applied by farmers was still well below the level required for optimal tilapia performance. Rural households benefited more than peri-urban households through enhanced direct consumption of fish and vegetables. In contrast, peri-urban households benefited more through cash sales of both fish and vegetables than rural households. Households with access to ponds, identified as relatively better-off and worse-off in the researched communities benefited equally selling and consuming fish and vegetable. Similar production levels of vegetable production between groups applying different fish culture practises suggesting that increased investment in fish production is complementary rather than competitive to vegetable production in integrated pond-dike farming systems. It was concluded that considerable potential exists to further develop pond-dike systems, which would improve livelihoods of both better-off and worse-off producers. Reference is made to the potential impacts of such changes in integrated pond-dike management if promoted more widely in Bangladesh.
|Livelihood impacts of ponds in Asia-opportunities and constraints
Little, D.C. ; Karim, M. ; Turongrouang, Danai ; Morales, E.J. ; Murray, F.J. ; Barman, B.K. ; Hague, M.M. ; Kundu, N. ; Belton, B. ; Faruque, A.S.G. ; Azim, M.E. ; Islam, F.U. ; Pollock, L. ; Verdegem, M.C.J. ; Young, J.A. ; Leschen, W. ; Wahab, M.A. - \ 2007
In: Fishponds in farming systems / van der Zijpp, A.J., Verreth, J.A.J., Wageningen : Wageningen Academic Publishers - ISBN 9789086860135 - p. 177 - 202.
|Water, not nutrients : the major focus of pond-based aquaculture integration within smallholder farms in Asia
Little, D.C. ; Karim, M. ; Wahab, M.A. ; Verdegem, M.C.J. ; Dang, L.N. ; Thanh, D. Le; Danai, T. ; Chitra, A. - \ 2005
In: Book of Abstracts World Aquaculture 2005, Bali, Indonesia, 9-13 May, 2005 - p. 360 - 360.
Excavated earthen ponds in tropical rain-fed farming systems are typically characterised, and promoted, as culture systems for around which whole-farm nutrient can be more efutilised. Research sites where ponds were common features of smallholder farms in Northeast Thailand, the Mekong Delta, Vietnam and central Bangladesh were identiand participatory research undertaken at the community-level. The research focus was to understand the current role of ponds within farming, and broader livelihood, systems and opportunities for enhancing benesub-sites were located in areas with high and low access to urban areas. At the rain-fed sites, where seasonal water scarcity was an issue (Thailand, Bangladesh), the importance of the pond as an on-farm source of irrigation water was paramount, whereas this was not the case in Vietnam where ponds and associated ditches were more related to a source of landand temporary supply and drainage of water respectively. In Thailand, ponds were generally not originally constructed with a view to optimising culture but rather to support associated dry season horticulture. In recent years their value for, and importance attached to aquaculture, had increased, but still fell far below potential. The importance of using pond water for seasonal cash crops, especially chilli, had become the major strategy among farmers and increasing the focus on, and benefrom, culture were not perceived as being complementary with this. In Bangladesh, ponds were also multipurpose but our analysis also showed interesting dynamic and potential for greater benefrom both the and crop production occurring in the immediate vicinity. In both these sites linkages between nutrients within ponds and surrounding aquaculture were weak and increasing inputs through intensieven seasonal culture was identias a strategy to enhance system productivity and beneThe cost of nutrients for horticulture was identiby farmers as a major problem. Improved mechanisms of reusing nutrients trapped in more intensively managed are therefore important. The production systems in Vietnam are resource intensive compared to the sites in Bangladesh and Thailand and higher levels of water exchange leads to local pollution. Low prices for most cultured herbivorous species has led farmers to prioritise improved systems for indigenous, usually carnivorous species, as a researchable issue. The concept of physically integrating water efreuse through adjacent extensive areas of ditch-dike orchard where a forage could be produced to support higher densities of high value carnivorous was identias a potential opportunity. In common with Bangladesh a signiproportion of farmers raising in Vietnam have commercial expectations and river cat(Pangasius hypothalamus) has been intensisigniin contrast to carp polycultures but this approach is not an option for resource-poorer farmers. The three sites therefore demonstrate a range of situations under which pond-based diversihas occurred, but that overall nutrient efremains poor under both rain-fed and perennially irrigated situations. Approaches that allow complementary intensiof and crop production in both contexts have potential.
|Nutrient flow in whole farm households: a case study in a village of Muktagach Upazila under Mymensingh district, Bangladesh
Kabir, M.S. ; Wahab, M.A. ; Karim, M. ; Verdegem, M.C.J. ; Little, D.C. - \ 2005
In: Book of Abstracts World Aquaculture 2005, Bali, Indonesia, 9-13 May, 2005 - p. 292 - 292.
|Adopting factors, existing patterns and potentials of integrated agriculture-aquaculture systems in rural and peri-urban areas of Bangladesh
Karim, M. ; Little, D.C. ; Wahab, M.A. ; Kabir, M.S. ; Verdegem, M.C.J. - \ 2005
In: Book of Abstracts World Aquaculture 2005, Bali, Indonesia, 9-13 May, 2005 - p. 302 - 302.
|Comparison between existing low input and high input integrated pond-dike aquaculture systems in some villages of Muktagacha, Mymensingh
Kabir, M.S. ; Wahab, M.A. ; Karim, M. ; Verdegem, M.C.J. ; Little, D.C. - \ 2004
Bangladesh Journal of Agricultural Sciences 2 (2004)1. - ISSN 0379-4296 - p. 103 - 112.