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Papers by John Hambrey
Marine Pollution Bulletin, 1999
This paper focuses on relationships between mangroves and coastal ®sh resources. A review of the ... more This paper focuses on relationships between mangroves and coastal ®sh resources. A review of the literature highlights the lack of quanti®ed relationships. We show that mangroves can be considered as a particular case of an estuarine environment, and then address the broader issue of the relationships between tropical estuaries and ®shery resources. An estuarine ®sh community is composed of three main assemblages, respectively from continental, strictly estuarine or marine origin. The major characteristics of these assemblages are de®ned. On this basis we detail the dierent and sometimes opposite impacts of major rehabilitation actions on each assemblage. The biological approach is then widened by a critical overview of current approaches in economic valuation of mangrove-related ®sh resources. This provides a rational and scienti®c foundation for economic analysis of resources and for coastal management decisions, and allows us to de®ne priorities for further scienti®c and policy research in these areas. Ó
The rapid unplanned expansion of coastal aquaculture in Bangladesh poses risks in degrading envir... more The rapid unplanned expansion of coastal aquaculture in Bangladesh poses risks in degrading environment. The unsustainable aquaculture practices are suspected to impart significant nutrient load to the ecosystem. Nevertheless, shrimp production is very less and susceptible to sever mortality. For this, the study aimed to understand the management practices and nutrient flux from some represented shrimp ponds in southwest coastal region of Bangladesh. A comprehensive study from 2002 to 2004 was done in an aquatic system comprising a river (Semi diurnal tidal system), a canal and 10 shrimp ponds along with wider area survey to verify the issues under a DFID-funded research project involving Nautilus Consultants Ltd. (UK). In the study area (Dumuria under the district Khulna) shrimp culture practices were mostly improved extensive. Shrimp were being produced without proper pond preparation, fry nursing, stocking or feed management due to lack of technical somehow and the risks involved with higher levels of investment. Consequently production rates were very low, averaging only 191 Kg/ha. Very high mortality of shrimp was reported in some of the farms using shallow ponds immediately after heavy rainfall. This may due to the sudden fluctuation of water pH and/or water temperature and salinity. The water quality in shrimp ponds during grow out period was in acceptable range except lower trend of DO and ammonia nitrogen. Year round water quality observations indicated that there were no major differences among the river, canal and pond water that might be due to the high water flushing rate (468%). The nutrient dynamics estimation indicates that 48.7 kg/ha/cycle of nitrogen and 28.96 kg/ha/cycle of phosphorus were added to the pond as an input mostly from fertilizer and feed. Among the inputs, only 33.4% of nitrogen and 6% of phosphorus were removed as harvested form. A large portion, 39.1% N and 92% P were remained in the sediments and unaccounted for. Average intake of nutrients through supply water was slightly higher than nutrient discharged through water outlet, which indicates a net retention of nutrients in the pond ecosystems. A large portion of this sediment nutrient eventually finds its routes into the wider aquatic system every year during pond preparation. Though the aquatic environment is able to accommodate the load from the present level of aquaculture practice, the assimilative power of aquatic environment is in danger of being degraded with the unplanned intensification of shrimp culture areas. In planning aquaculture and future development all the issues and impacts must be considered.
The price of this fish remained stable in 2000. Cultured fish of 0.5-0.8 kg could be sold at abou... more The price of this fish remained stable in 2000. Cultured fish of 0.5-0.8 kg could be sold at about HK$ 95-100/catty. At least one hatchery in Taiwan and two hatcheries in Bali, Indonesia, produced high-finned grouper (Cromileptes altivelis) fry. Taiwan culture fishermen are not interested in this species because it grows very slowly and cannot be reared in ponds there.
Marine Pollution Bulletin, 1999
This paper focuses on relationships between mangroves and coastal ®sh resources. A review of the ... more This paper focuses on relationships between mangroves and coastal ®sh resources. A review of the literature highlights the lack of quanti®ed relationships. We show that mangroves can be considered as a particular case of an estuarine environment, and then address the broader issue of the relationships between tropical estuaries and ®shery resources. An estuarine ®sh community is composed of three main assemblages, respectively from continental, strictly estuarine or marine origin. The major characteristics of these assemblages are de®ned. On this basis we detail the dierent and sometimes opposite impacts of major rehabilitation actions on each assemblage. The biological approach is then widened by a critical overview of current approaches in economic valuation of mangrove-related ®sh resources. This provides a rational and scienti®c foundation for economic analysis of resources and for coastal management decisions, and allows us to de®ne priorities for further scienti®c and policy research in these areas. Ó
The rapid unplanned expansion of coastal aquaculture in Bangladesh poses risks in degrading envir... more The rapid unplanned expansion of coastal aquaculture in Bangladesh poses risks in degrading environment. The unsustainable aquaculture practices are suspected to impart significant nutrient load to the ecosystem. Nevertheless, shrimp production is very less and susceptible to sever mortality. For this, the study aimed to understand the management practices and nutrient flux from some represented shrimp ponds in southwest coastal region of Bangladesh. A comprehensive study from 2002 to 2004 was done in an aquatic system comprising a river (Semi diurnal tidal system), a canal and 10 shrimp ponds along with wider area survey to verify the issues under a DFID-funded research project involving Nautilus Consultants Ltd. (UK). In the study area (Dumuria under the district Khulna) shrimp culture practices were mostly improved extensive. Shrimp were being produced without proper pond preparation, fry nursing, stocking or feed management due to lack of technical somehow and the risks involved with higher levels of investment. Consequently production rates were very low, averaging only 191 Kg/ha. Very high mortality of shrimp was reported in some of the farms using shallow ponds immediately after heavy rainfall. This may due to the sudden fluctuation of water pH and/or water temperature and salinity. The water quality in shrimp ponds during grow out period was in acceptable range except lower trend of DO and ammonia nitrogen. Year round water quality observations indicated that there were no major differences among the river, canal and pond water that might be due to the high water flushing rate (468%). The nutrient dynamics estimation indicates that 48.7 kg/ha/cycle of nitrogen and 28.96 kg/ha/cycle of phosphorus were added to the pond as an input mostly from fertilizer and feed. Among the inputs, only 33.4% of nitrogen and 6% of phosphorus were removed as harvested form. A large portion, 39.1% N and 92% P were remained in the sediments and unaccounted for. Average intake of nutrients through supply water was slightly higher than nutrient discharged through water outlet, which indicates a net retention of nutrients in the pond ecosystems. A large portion of this sediment nutrient eventually finds its routes into the wider aquatic system every year during pond preparation. Though the aquatic environment is able to accommodate the load from the present level of aquaculture practice, the assimilative power of aquatic environment is in danger of being degraded with the unplanned intensification of shrimp culture areas. In planning aquaculture and future development all the issues and impacts must be considered.
The price of this fish remained stable in 2000. Cultured fish of 0.5-0.8 kg could be sold at abou... more The price of this fish remained stable in 2000. Cultured fish of 0.5-0.8 kg could be sold at about HK$ 95-100/catty. At least one hatchery in Taiwan and two hatcheries in Bali, Indonesia, produced high-finned grouper (Cromileptes altivelis) fry. Taiwan culture fishermen are not interested in this species because it grows very slowly and cannot be reared in ponds there.