Response to selection for growth in an interspecific hybrid between Oreochromis mossambicus and O. niloticus in two distinct environments

The development of a saline tolerant tilapia strain able to grow fast is of importance in the Philippines, where 240 000 ha of brackish water ponds are available. To this end, founder hybridization between Oreochromis niloticus (with favorable growth traits) and O. mossambicus (with favorable salinity tolerance traits) was performed and followed by backcrossing with O. mossambicus to develop a strain highly tolerant to saline environments. Genetic selection for growth performance was subsequently conducted.

Preliminary analysis of demersal fish assemblages in Malaysian waters

Spatial and temporal variations of the demersal fisheries resources of Malaysia were studied using multivariate analysis of their abundance (biomass) from research trawl surveys in relation to geographical and environmental parameters. TWINSPAN results indicate that the demersal resources of Malaysia can be geographically divided into five major species assemblages. Two assemblages are in Peninsular Malaysia and three assemblages are in Sabah and Sarawak waters.

Preliminary observation on culture of Penaeus monodon in low-saline waters.

The feasibility of semi-intensive culture of Penaeus monodon in low saline environment was investigated by comparing the growth and production in low (0.16-6.52 ppt) and high (4.60-19.42 ppt) saline areas at two stocking densities (10.5 and 16 individuals/m super(2)). After 135 days of culture, yield of shrimp in low and high stocking densities was 1563.37 kg/ha and 2274 kg/ha, respectively, in low saline ponds, and 1173.00 and 1974.00 kg/ha, respectively in high saline ponds.

Evolution of shrimp aquaculture systems in the coastal zones of Bangladesh and Vietnam: a comparison

Based on on-farm surveys implemented in the Ganges Delta in Bangladesh and the Mekong Delta in Vietnam, the dynamics of shrimp aquaculture in salinity-influenced coastal areas were analysed. Qualitative data were collected through interviewing both individual and group farmers in 2005 and 2006, as well as key informants and value chain stakeholders, to obtain an overview of the dynamics of salinity-influenced aquaculture in these two deltas.

Effect of different salinity levels on the fertilization and hatching of Heterobranchus bidorsalis.

The success of induced spawning for the production of fish seed depends on many factors which affect hatchery conditions. This paper discusses the results of an investigation on the effects of six different levels of salinity on the fertilization and hatching of Heterobranchus bidorsalis eggs. The results indicate that spermatozoa of H. bidorsalis can survive under a wide range of saline concentrations, with survival increasing with an increase in salinity from 0 to 0.4% and then decreasing as the level of salinity increases. Survival was optimum of 0.4% saline concentration.

Breeding and rearing of the sea cucumber Holothuria scabra in Viet Nam

The aims of this project were to develop large scale breeding and rearing methods for sandfish (Holothuria scabra) for commercial culture and/or restocking. Wild collected sea cucumbers were initially difficult to spawn, but after a period in earthen ponds or seabed pens could be induced year-round, using temperature changes, emersion, treatment of water with UV light, and addition of dry phytoplankton. Numerous batches of larvae were reared to settlement and to larger sizes using simple hatchery methods.

Aquaculture [in Vietnam]

This report provides a synthesis of key findings of sector studies undertaken in Vietnam in the context of the Economics of Adaptation to Climate Change (EACC) study. Sectors studied include agriculture, forestry, coastal port and aquaculture. Aquaculture, especially in the Mekong River Delta, is an important source of employment and rural income. The main impacts of climate change on aquaculture seem likely to be a consequence of increased flooding and salinity.

Spawning and hatching performance of the silvery black porgy Sparidentex hasta under hypersaline conditions

Abu Al Abyad island is characterized by harsh environmental conditions. A preliminary trial conducted at the island to investigate the spawning and hatching performance of the blue finned sea bream Sparidentex hasta indicated that the fish can be successfully bred at high salinity levels exceeding 50 ppt.

Experimental rearing of Nile tilapia fry (Oreochromis niloticus) for saltwater culture.

Represents a preliminary evaluation of the utility of various approaches of early salinity exposure for saltwater culture of tilapias. Studies the reproductive performance of Nile tilapia under laboratory conditions at various salinities; salinity tolerance of progeny; survivorship of fertilized eggs, spawned in freshwater but removed from the mouth of the parent female and artificially incubated at various salinities.

Effect of transportation stress on hepatic glycogen of Oreochromis niloticus (L.) .

Oreochromis niloticus was subjected to transportation stress to investigate hepatic glycogen levels and mortality as indices of stress. Mortalities lasted up to three days after transportation, except in highly aerated samples. Heptic glycogen levels in transported fish were significantly lower in the controls. Stress appeared to be more intense when fish were transported at a high density and in a high salinity medium.

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