LENGTH-WEIGHT RELATIONSHIP AND CONDITION FACTOR OF Salmophasia bacaila (Hamilton, 1822) OF THE RIVER DHEPA IN BANGLADESH

Abstract

The purpose of the study was to determine the length-weight relationships and condition factor of Salmophasia bacaila (Hamilton, 1822). A total of 932 Salmophasia bacaila individuals were collected as sample from the Dhepa river of Dinajpur district over a calendar year from November 2016 to October 2017 Linear regression (Y= a+bX) analyses and power curve equation BW= aSLb were used to establish the relationship between standard length (mm) and body weight (g). The generalized standard length (SL) ranged from 35 mm to 122 mm and body weight (BW) varied from 0.67g to 21.56 g. In male, the ‘a’ value ranged from 0.000007 to 0.016809 and ‘b’ value ranged from 1.376 to 3.026. The generalized relationship of all male population over the study period was BW= 0.000072 SL2.506 . The value of a' and CFBW ranged from 0.000008-0.016865 and 1.013-1.105, respectively. It showed that maximum male fish were in ideal condition on November 2016 and August 2017 and the rest were in fatty. In female, the ‘a’ value ranged from 0.000005 to 0.001540, and the ‘b’ value ranged from 1.847 to 2.992. The generalized relationship of all female population over the experiment was BW= 0.000106 SL2.425 . The value of a' and CFBW ranged from 0.000006-0.001550 and 1.006-1.090, respectively. It was showed that maximum female fish were in ideal condition on March 2017, September 2017 and October 2017 and the rest were in fatty. For combined population, the ‘a’ value ranged from 0.000007 to 0.00170, and the ‘b’ value ranged from 1.692 to 3.01. The generalized relationship of all population over the study period was BW= 0.000054 SL2.577 . The value of a' and CFBW ranged from 0.000008-0.002999 and 1.008-1.105, respectively. In this case, maximum fish were found in ideal condition on November 2016, December 2016, March 2017, August 2017 and September 2017 and the rest were in fatty condition. The correlation coefficient (r) of male, female and combined population ranged from 0.525-0.978, 0.542-0.930 and 0.683-0.944. These indicated that the length-weight relationships of this species were highly correlated and they were seen either in ideal or fatty condition. This information obtained from this study will be helpful for the fishery managers in adequate regulations for sustainable fishery management in Dhepa river of Dinajpur district or other water bodies of the other part of the country.