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Deein G.,Inland Fisheries Research and Development Bureau | Tangjitjaroen W.,Chiang Mai University | Page L.M.,University of Florida
Zootaxa | Year: 2014

Lepidocephalus has been assumed to include only two species and confined to peninsular Malaysia and Indonesia. How-ever, based on records and collections reported herein, the genus contains five species and is most common in the Chao Phraya basin of Thailand. Large rivers seem to be the preferred habitat, and difficulty in collecting these rivers may ac-count for the paucity of specimens in collections. The known range of these five species includes western and southern Borneo, Java, Sumatra, peninsular Malaysia, and central Thailand Copyright © 2014 Magnolia Press. Source

Phomikong P.,Ubon Ratchathani University | Fukushima M.,Japan National Institute of Environmental Studies | Sricharoendham B.,Inland Fisheries Research and Development Bureau | Nohara S.,Japan National Institute of Environmental Studies | Jutagate T.,Ubon Ratchathani University
River Research and Applications | Year: 2015

Diversity and community structure of fishes were studied in three neighbouring tributaries of the Mekong River in Thailand, namely the Mun, Songkhram and Gam Rivers. The rivers are located in the same ecoregion but have contrasting levels of both hydrological regulations and mitigation measures; the Mun River has a hydropower dam with a fish ladder and sluice gates that are opened during the wet season each year, the Gam River has several irrigation dams with a fish ladder at each dam site, and the Songkhram River has no dams along its river course. A total of 124 freshwater fish species were sampled in these rivers from August 2009 to June 2010. Overall species richness was highest in the Songkhram River (112), followed by the Mun (97) and Gam (54) Rivers. Average per site species richness was also significantly different among rivers but not among sampling months. Abundance-biomass comparison plots revealed considerably overlapping distributions of these two metrics from the dry to early rainy seasons in the Songkhram River and, to a lesser extent, in the Mun River. Fish assemblage data were classified into six clusters with similar community structure. Fish assemblages in the Gam River constituted a single cluster, while those in the other two rivers formed multiple clusters depending on the sampling season. The results of the cluster analysis are discussed in relation to the dominance of the three migration guilds (white, black, and grey fishes) of the Mekong River fishes. The effectiveness of the mitigation measures was determined to be limited in alleviating adverse impacts of dams in these tributaries of the Mekong River. © 2015 John Wiley & Sons, Ltd. Source

Koolboon U.,Kasetsart University | Koonawootrittriron S.,Kasetsart University | Kamolrat W.,Inland Fisheries Research and Development Bureau | Na-Nakorn U.,Kasetsart University
Aquaculture | Year: 2014

The hybrid between Clarias macrocephalus female × C. gariepinus male has been cultured in Thailand for more than 20. years, but the effects of parental strains have not been studied. In the present study, differences among three strains each of C. macrocephalus and C. gariepinus were shown by the analyses of five microsatellite loci (FST= 0.174 ± 0.037). Pairwise FST within species was significantly higher than zero (P= 0.0000) for every population pair, and ranged from 0.027 to 0.041 for C. macrocephalus and from 0.087 to 0.254 for C. gariepinus. Interspecific hybridization was performed using females from C. macrocephalus and male C. gariepinus, resulting in nine hybrid crosses. Performance traits of the hybrids were compared with the offspring of three crosses each within C. macrocephalus and C. gariepinus. The experiments were done in tanks from 28 to 84. days old, and in cages fixed in an earthen pond from 85 to 175. days old. The results showed that the effects of both parental strains and their interaction on the absolute growth rate and specific growth rate (SGR) from 28 to 84. days old were significant. Absolute growth rates during 85 to 175. days were significantly affected only by strains of C. gariepinus, while neither parental strains affected SGR from 85 to 175. days old of the hybrids. The effects of the parental strains and their interaction were not significant for other traits, including the survival rate from 28 to 84. days old and 85 to 175. days old, dress-out percentage, fillet yield, phagocytic activity and phagocytic index. It was noteworthy that the difference in traits among crosses within each genetic group (C. macrocephalus, C. gariepinus, and hybrids) was significant only for growth traits (absolute growth rates from 28 to 84. days and from 84 to 175. days among strains of C. gariepinus, and among hybrids; the SGR from 28 to 84. days old and 85 to 175. days old within C. macrocephalus, and the SGR from 28 to 84. days old within the hybrids). Mean heterosis was low and not notable (< 1%) in most cases, except for the survival rate from 28 to 84. days old and 85 to 175. days old (+ 2.43 ± 2.14 and + 10.71 ± 4.71%, respectively), absolute growth rate from 85 to 175. days (+ 10.85 ± 11.35%), and percent fillet yield (+ 1.34 ± 1.73%). Variation of heterosis among the hybrid crosses was observed. Among the nine hybrid crosses, the cross between female C. macrocephalus from Udorn Thani province (Cma-UD) × C. gariepinus from the Department of Aquaculture (Cga-AQ) showed the highest proportion of positive heterosis across ten traits (90%). © 2013 Elsevier B.V. Source

Poompoung P.,Kasetsart University | Poompuang S.,Kasetsart University | Kamonrat W.,Inland Fisheries Research and Development Bureau
Kasetsart Journal - Natural Science | Year: 2012

This study aimed to determine the possibility of using temperature manipulation to stimulate ovarian activities of Clarias macrocephalus during the post-spawning season. The ovarian development and monthly change in the gonado-somatic index (GSI) of females held under pond conditions was monitored over a 1 yr period from April 2008 to March 2009. In October, 13 mth-old female fish (weight ± SD= 108 ± 12.7 g) were randomly collected from an earthen pond and exposed to different temperatures at 25, 30 and 35 °C under hatchery conditions for 6 wk. The results indicated that the change in the GSI appeared to be correlated with the amount of rainfall, but not to the variation in seasonal temperature. A significant (P < 0.05) variation of mean GSI values was observed among months with the highest value ± SE (13.91 ± 3.63%) in July. Histological examination of ovaries revealed that in females held under 25, 30 and 35 °C, the number of vitellogenic oocytes progressively increased from 0.5-4.7% at week 2 to 4.6-19.7% at week 6, whereas in females held in the earthen pond, ovaries contained only immature oocytes. Exposure to warm temperatures resulted in significant elevations of plasma cortisol but not glucose concentrations. Although fully matured females could not be obtained, the present study suggested that temperature manipulation was probably the practical way to increase the number of maturing females during the off reproductive season for walking catfish. Source

Munpholsri N.,Kasetsart University | Poompuang S.,Kasetsart University | Senanan W.,Burapha University | Kamonrat W.,Inland Fisheries Research and Development Bureau
Kasetsart Journal - Natural Science | Year: 2013

The Indian mackerel (Rastrelliger kanagurta) fishery in Thailand has experienced declining catches during the past several years and was identified as over-exploited. The study obtained population genetic information to support the ongoing management of the fishery. Six microsatellite loci from short mackerel (Rastrelliger brachysoma) were screened to assess the genetic diversity in Indian mackerel stocks from four localities on the Andaman Sea coast. All population samples exhibited similar and moderate genetic variation with an average of 6.5 to 7.8 alleles per locus and average expected heterozygosity at all loci of 0.60 to 0.69. There was no evidence to support population substructure (overall genetic differentiation = FST = 0.012; non-significant pairwise FST values). Gene flow was detected through the presence of rare alleles at three loci across samples. The contemporary estimated effective population size was approximately 330 if a single stock unit was considered. This moderate size of the breeding population is crucial for the short-term conservation of genetic variability in Indian mackerel stocks. Genetic data from the present study provides baseline genetic information and supports the management of Indian mackerel as a single unit. Source

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