Temporal variation of sex ratio, growth pattern and physiological status of Eutropiichthys vacha (Schilbeidae) in the Ganges River, NW Bangladesh

ABSTRACT

The present study illustrates the first complete temporal variations of sex ratio (SR), length-frequency distributions (LFDs), growth pattern based on length-weight relation (LWR), length-length relationships (LLRs) and physiological status of Eutropiichthys vacha in the Ganges River, Bangladesh. A total of 1386 specimens (male = 652, female = 734) were collected from the fishers catch during January to December, 2016. For each individual, total length (TL), fork length (FL), standard length (SL) and body weight (BW) were measured using digital slide calipers and electronic balance with 0.01 cm and 0.01 g precision. The overall SR differed statistically from the expected 1:1 ratio, although females were greater in percentage throughout the year, except in April. The TL of males and females ranged from 6.2–19.9 cm and 6.5–20.6 cm, respectively. The overall growth pattern was negative allometric for both sexes, though ANCOVA reveals significant difference in LWRs. All LLRs were highly significant with r² > 0.962. The highest percentage of fatty fish was found in April and March whereas the lowest was in August for both sexes. Finally, these findings will be useful for further studies and to suggest sound policy for the sustainable management of E. vacha in the Ganges River ecosystem.

KEYWORDS:

• Sex ratio
• growth pattern
• physiological status
• Eutropiichthys vacha
• Ganges River

Acknowledgments

The authors would like to extend their sincere gratitude to the (i) TWAS for Research Grants (Ref: RGA No. 14-028 RG/BIO/AS_1; UNESCO FR: 324028574) for technical support and (ii) Ministry of Education, Bangladesh (No. 37.200000.004.003.005.2014-1309/1 (42); date: 10.08.2014) for funding this research. Reviewers are thanked for their suggestions in improving the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.