1000 resultados para T. tambroides and
Resumo:
The Mahseers (<i>Tor spp.</i>) are highly valued freshwater fishes across the Himalayan and South-east Asian regions. Over exploitation of natural stocks because of high demand and the deteriorating environmental conditions have resulted in marked decline of mahseers in the wild. Malaysian mahseers, <i>T. tambroides</i> (Bleeker) and <i>T. douronensis</i> (Valenciennes), locally known as empurau, kelah or belian and semah, respectively, have significant cultural and economic importance but both species are now threatened in the wild because of environmental degradation and over fishing. A captive breeding programme was instigated to attempt to propagate these two species artificially for conservation and aquaculture purposes. Both pond-reared and tank-held <i>T. tambroides</i> and <i>T</i>. <i>douronensis</i> reached sexual maturity in captivity and were successfully induced to spawn using hormone treatments. Ovaprim (0.5 mL kg<sup>−1</sup>) was the most successful hormone treatment for both species. Pre-treatment of fish with Ovaplant (28–68 μg kg<sup>−1</sup>, 2–7 weeks before spawning induction) greatly improved the success rate of spawning induction. Repeat spawning (within 4 months of initial spawning) was induced in some captive fish. Use of formalin baths improved hatching by preventing fungal infections. Embryonic development and hatching are described. Juveniles were reared in static greenwater ponds. <i>Tor tambroides</i> reached 142–179 g (max 270 g) in 60 weeks. These results represent the first successful captive spawning and rearing of both species. Options for future research to improve production are discussed.<br />
Resumo:
<i>Tor tambroides</i> and <i>T. douronensis</i>, locally referred to as empurau and semah, respectively, are high valued mahseer species, indigenous to Sarawak, East Malaysia, with an aquaculture potential and of conservational value. Direct sequencing of mitochondrial DNA (mtDNA) 16S rRNA gene region (542 bp) was used to investigate genetic variation of <i>T. tambroides</i> and <i>T. douronensis</i> broodstock collected from different geographic locations in Sarawak and maintained at the Indigenous Fish Research and Production Center (IFRPC), Tarat, Sarawak, Malaysia. A total of 11 unique haplotypes were identified, of which six were detected in <i>T. tambroides</i>, and five in <i>T.</i> <i>douronensis</i>. Overall, nucleotide diversity (<i>π</i>) was low, ranging from 0.000 to 0.006, and haplotype diversity (<i>h</i>) ranged from 0.000 to 0.599. Although the analysis failed to detect genetic variation amongst populations of <i>T.</i> <i>tambroides</i> (significant pairwise FST was found for only one test, but pairwise haplotype frequencies were not statistically significant), substantial inter-population divergence among <i>T. douronensis</i> was recognised, especially those originating from different river systems (pairwise F<sub>ST</sub> = 0.754 to 1.000, <i>P</i> < 0.05). Fixed haplotype differences were found in one population of T. douronensis. Average nucleotide divergence between <i>T. </i><i>tambroides</i> and <i>T. douronensis</i> was 0.018, similar to the amount recognised between <i>T. tambroides</i> and the outgroup <i>T. khudree</i> (0.017). In addition, phylogenetic analysis revealed that the <i>T. douronensis</i> mtDNA consisted of two highly divergent clusters (0.020), one of which is more closely related to <i>T. tambroides</i> rather than with the other group of haplotypes of the conspecifics. The findings from the present study have important implications for aquaculture, management and conservation of these two species. The data also raise some concerns regarding the taxonomic status of <i>T. douronensis</i>, which needs to be addressed.<br />
Resumo:
The study focuses on the natural spawning ecology, induced spawning of captive broodstock and larval and fry nursing techniques of Tor tambroides and Tor douronensis, two mahseer fish of aquaculture and conservational importance. Both species were induced bred, and the development will help develop commercial aquaculture.
Resumo:
This study reports the isolation and characterization of microsatellite DNA markers in a mahseer species, Tor tambroides (Pisces, Cyprinidae). Of a total of 14 loci evaluated, 10 were polymorphic in T. tambroides samples, with an average of 2.86 alleles per locus. Deviations from Hardy–Weinberg equilibrium were observed at one locus and there was no indication of linkage disequilibrium among loci. A high level of cross-amplification among four congeners was achieved, with 12 loci successfully amplifying and 11 loci showing polymorphism in at least one other species. These markers will be a useful resource for population genetic studies and broodstock management of closely related mahseer species.<div id="refHTML"></div>
