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Landmark-based Morphometric and Meristic Variations of the Critically Endangered Catfish, Eutropiichthys Vacha from Three Different Populations in Bangladesh

M. Rashed Parvej
Department of Fisheries & Marine Science, Noakhali Science & Technology University, Sonapur, Noakhali-3814, Bangladesh

M.R. Islam
Department of Fisheries & Marine Science, Noakhali Science & Technology University, Sonapur, Noakhali-3814, Bangladesh

Maruf Hossain Minar
Extension Officer, National Agricultural and Technology Project, Senior Upazilla Fisheries Office, ChandpurSadar, Chandpur

M. Belal Hossain
Environmental and Life Sciences, Faculty of Science, Universiti Brunei Darussalam, Brunei BE1410

M.R. Tushar
Department of Fisheries & Marine Science, Noakhali Science & Technology University, Sonapur, Noakhali-3814, Bangladesh

Abstract/ Executive Summary:

Variation in shape, morphometric & meristic characters of critically endangered catfish Bacha, Eutropiichthys Vacha, populations from Kaptai Lake, Meghna River &TanguarHaor (wetland ecosystem) were investigated. A total of twenty-six fish (eight from the Meghna river, eight from KaptaiLake & ten from Tanguarhaor) samples (as this species is rarely found) were collected from March to November 2012. Eighteen morphometric & four meristic characters were analyzed along with twenty-two truss network measurements. Non-parametric Kruskal-Wallis test was used to compare meristic counts and no significant differences were observed among populations. ANOVA showed significant morphometric differences (p<0.001) in three (Pectoral fin Length, Snout length, & Eye Diameter) of seventeen morphometric measurements among the populations. None of the twenty-two truss network measurements among the populations was significantly different (p>0.001). For morphometric & landmark measurements, the first discriminant function (DF) accounted for 97.7% & 99.7% & the second DF accounted for 2.3% & 0.3%, respectively, among-group variability and together they explained 100% of the total among group variability. For the morphometric & truss network measurements, plotting discriminant functions revealed high isolation of the populations. The dendrogram based on morphometric &landmarks distances placed Tanguarhaor&Kaptai Lake in one cluster & the Meghna River in another cluster. Due to similar environmental conditions & less geographical differences, all the landmark of truss measurements did not contribute to significant body shape differences among the populations. These all analyses will be an effective tool to describe the body shape variation of a fish species.

Keywords: Landmark, Critically Endangered, Population, Eutropiichthys vacha

Location: Kaptai Lake in Rangamati District, the Meghna River in Laxmipur District, & Tanguar Haor in Sunamganj District, Bangladesh

Start Date: 00-03-2012

End Date: 00-11-2012

Program Area: Variety and Species

Commodity: Cat fish

Objectives:

To identify the genetically diversified Bacha populations so that recommendations can be given to minimize the level of threat on this endangered species.

Methodology:

Collection of Samples: During March to November, 2012, 26 bacha (E. vacha) were collected from three different sources Kaptai Lake in Rangamati District, the Meghna River in Laxmipur District, & Tanguar Haor in Sunamganj District. The fish were 18.6-28.4 cm in total length(TL) & 36-152 g in weight. The specimens were transported in icebox to the laboratory, where measurements started immediately to avoid shrinkage. Eighteen morphometric measurements were made on each specimen. The body parts were measured following standard anatomical reference points. Four Meristic Characters Were Studied: Dorsal fin rays (DFR); pectoral-fin rays (PcFR); pelvic fin rays (PvFR); anal fin rays (AFR) were estimated for this study. A magnifying glass was used to count the fin rays & only the principal rays were counted as a separate ray. For measurement of Landmarks distances of the species the truss network system described for fish body morphometric [9, 10] was used to construct a network on fish body. Eleven landmarks determining twenty-two distances were produced and measured as illustrated. Data points were arranged in “trusses” around the fish a layout which maximizes the number of measurements & increases the sensitivity of the analysis. Each landmark was obtained from the distances on the graph paper which were measured using Vernier calipers. Statistical Analysis: One-way analysis of variance (ANOVA) was performed for the comparison of the morphometric data. A multivariate discriminant analysis was used for morphometric data to identify the combination of variables that best separate E. vacha species. But before analysis size effects as because most of other variabilities will occur and that’s why it was necessary to remove size-dependent variation for all the characters. Using Elliott et al. [16] allometric formula variations resulting from allometric growth were eliminated and data were standardized. The formula is given below: M = M (L / L )b. where M: Original measurement, Madj: Size adjusted measurement, Lo: Total length of fish, & Ls: Overall mean of total length for all fish from all samples. Parameter b was estimated for each character from the observed data as the slope of the regression of log M on log Lo, using all fish in all groups. The degree of similarity among samples in the overall analysis & relative importance of each measurement for group separation were assessed by discriminant function analysis (DFA) with cross-validation. Population centroids with 95% confidence ellipses derived from the DFA were used to visualize relationships among the individuals of groups. Comparison of meristic characters was done using the non-parametric Kruskal-Wallis test. All statistical analyses were done using SPSS v 11.5 (SPSS, Chicago, IL, USA).

Source of Information: World Journal of Fish and Marine Sciences 6 (4): 378-385, 2014; ISSN 2078-4589

Article Link (Online Journal): DOI: 10.5829/idosi.wjfms.2014.06.04.85117

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

The result of this study may be used as storage of information about bacha & can be used for further studies. It should be emphasized that the application of genetic techniques would be very beneficial to confirm the detected phenotypic differentiation. More research is needed, especially on the basis of genetic studies and research into the causes of the environmental factor for the conservation of a species as critically endangered, bacha in Bangladesh.

Knowledge Management: Journal