Most. Farida Parvin*
Institute of Environmental science (IES), University of Rajshahi, Rajshahi-6205, Bangladesh
Akhery Nima
Department of Fisheries, Faculty of Agriculture, University of Rajshahi, Rajshahi-6205, Bangladesh
Farzana Akter Rima
Department of Fisheries, Faculty of Agriculture, University of Rajshahi, Rajshahi-6205, Bangladesh
Md. Yeamin Hossain
Department of Fisheries, Faculty of Agriculture, University of Rajshahi, Rajshahi-6205, Bangladesh
Growth Pattern; Heteropneustes fossili; Size; Sexual Maturity; Natural Mortality.
Padma River in Bangladesh; northwestern part of Bangladesh
Animal Health and Management
2.1.Sampling and Measurement The present study was carried out in the Padma River in Bangladesh (Charghat: 24°15' N, 88°44' E; and Shaheb Bazaar: 24°20' N, 88°34'), northwestern part of Bangladesh. Samples of H. fossilis were collected occasionally from the fishers’ catch during July 2018 to June 2019. The random sampling method was used for sampling of fish. This fishes typically captured by using different types of traditional fishing gears like, gill net, cast net square lift net, etc. Collected specimens were instantly chilled in ice on site and preserved with 10% buffered formalin upon arrival in the laboratory. For each individual total length (TL) and standard length (SL) were taken to the nearest 0.01 cm by using digital slide calipers, and body weight (BW) was measured to the nearest 0.01 g by using an electric balance with 0.01 g accuracy.
2.2. Population Structure The LFD for the H. fossilis was constructed using 1 cm intervals of TL. Based on Hasselblad’s maximum likelihood method (Hasselblad, 1966) the normal distribution was fitted to TL frequency distributions.
2.3. L-W Relationships In order to length weight relationships this equation was used: BW= a*(TL)b, where BW is the total body weight (g) and TL is the total length (cm). The parameters a and b were calculated by linear regression analyses based on natural logarithms: ln (BW) = ln (a) + b ln (TL). Extremes outliers were deleted from the regression analyses according to Froese (2006). Additionally, on the basis of the b values of LWR (TL vs. BW), growth pattern of H. fossilis was determined.
The allometric condition factor (KA) was calculated using the equation of Tesch (1968). The Fulton’s condition factor (KF) was calculated using the equation of Fulton (1904). The scaling factor of 100 was used to bring the KF close to unit and the relative condition factor (KR) for each individual was calculated using the equation of Le Cren (1951).
2.4. Prey-Predator Status and Form Factor (a3.0) The prey-predator status of H. fossilis was determined through the relative weight (WR). The WR was calculated by the equation given by Froese (2006). The form factor (a3.0) for H. fossilis was calculated using the expression given by Froese (2006).
2.5. Size at First Sexual Maturity (Lm) and Natural Mortality (MW) The Lm of H. fossilis in the Padma River was calculated by using the equation of Binohlan and Froese (2009). The MW was considered by the model of Peterson and Wroblewski (1984).
2.6. Statistical Analysis For statistical analysis, GraphPad Prism 6.5 software was used. The Wilcoxon signed rank test was applied to compare the mean relative weight (WR) with 100 (Anderson and Neumann 1996). Additionally, data analyses were done through Microsoft-Excel-add-in-Solver. All statistical analyses were considered significant at 5% (p<0.05).
Rajshahi University Journal of Environmental Science, 8: 51-58, 2019
Journal