Abstract
BackgroundWild fish populations stock is continuously diminishing in the Indo-Ganges river basin, and the population status of most fishes is unidentified. The identification of the population status and the conservation of commercially important and endemic wild fish populations in this region are crucial for the management. The aim of this paper was to identify the population status of Cirrhinus reba, a promising aquaculture but vulnerable species in the Indo-Ganges river basin in Bangladesh.MethodsC. reba samples were collected from four isolated populations of the Brahmaputra (n = 30), the Padma (33), the Karatoya (31), and the Jamuna Rivers (30) in Bangladesh, and the population status was evaluated using morphometric and landmark comparisons. Data were analyzed with the Kruskal-Wallis test, univariate analysis, discriminant function analysis, and the formation of a dendrogram.ResultsThree meristic characters (Pectoral fin rays, caudal fin rays, scale in lateral lines), four morphometric characters (head length, pre-orbital length, post-orbital length, maximum body depth), and truss measurement (4–7) were significantly different among the stocks. The step-wise discriminant function analysis retained 15 variables from morphometric and landmark measurements that significantly differentiated the populations based on the constructed DFI and DFII. Discriminate function analysis also showed that 91.2% of the original groups were classified into their correct samples. The cluster analysis of Euclidean distances placed the Jamuna population in one cluster and the Brahmaputra, the Padma, and the Karatoya populations in the second one.Conclusion Morphological differences among the stock were probably due to different ancestral origin. This is the first report about population status of C. reba in their natural habitat of the Indian subcontinent. Further genetic studies and the evaluation of environmental impact on C. reba populations in Bangladesh are suggested to support our findings.
Highlights
Wild fish populations stock is continuously diminishing in the Indo-Ganges river basin, and the population status of most fishes is unidentified
Pooled within groups correlation between discriminant variables and DFs revealed that among the morphometric measurements, the post-orbital length (post-OL) and the head length (HL) dominantly contributed to the first DF while, the pre-OL and the pre-dorsal length (Pre-DL) contributed to the second DF and the rest contributed to the third DF (Additional file 6: Table S4)
The discriminant function analysis showed that the overall allotment of individuals into their original populations was high (91.2%)
Summary
Wild fish populations stock is continuously diminishing in the Indo-Ganges river basin, and the population status of most fishes is unidentified. The identification of the population status and the conservation of commercially important and endemic wild fish populations in this region are crucial for the management. The aim of this paper was to identify the population status of Cirrhinus reba, a promising aquaculture but vulnerable species in the Indo-Ganges river basin in Bangladesh. The management and conservation strategy for different species, subspecies, stocks, and races depends on the information of biology and population structure of that particular group (Turan et al 2006). Intraspecific variability in life history attributes in terms of growth, maturation, and development induce morphometric differences between species (Cadrin 2000). In a small country like Bangladesh, where there are probably very small environmental changes from place to place, the resulting morphological differences in fish may be so small that they might be impossible to discern with gross morphometric characters
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