JnU Correspondent

A team of researchers from the Department of Zoology at Jagannath University (JnU) and the Department of Hydrobiology at Shanghai Ocean University, China jointly conducted three significant studies on Hilsa, the national fish of Bangladesh. The research projects focus on Sex Reversal in Hilsa, Complete Genome Analysis, and Population Genomics.

The findings of these studies were presented at a seminar and press conference held on Thursday morning at the Department of Zoology, JnU.

The event was graced by Prof Dr. Md. Rezaul Karim, Vice-Chancellor of JnU, as the chief guest. Professor Dr. Abdullah Al Masud, Chairman of the Department of Zoology, presided over the seminar, while special guests included Prof Dr. Sabina Sharmin, Treasurer of JnU; Prof Dr. Mallik Akram Hossain, Dean of the Faculty of Life and Earth Sciences; Md. Zia Haider Chowdhury, Additional DG of the Department of Fisheries; and Prof Dr. Imranul Haque, Director of Research at JnU.

According to the study, 203 Hilsa specimens of different ages and sizes were collected from six locations across the Padma, Meghna, and the Bay of Bengal. Notably, seven specimens exhibited the simultaneous presence of sperm and eggs in their gonadal tissues, indicating sex reversal in Hilsa.

Researchers hypothesize that Hilsa functions as a male in its first year for reproduction and then migrates to the sea in search of food. Over time, it gradually transforms into a female and returns to the river in its second year for spawning. This research marks a significant milestone in unraveling the complete life cycle, reproductive strategies, and sex transformation of Hilsa.

For the first time, researchers have decoded the complete genome sequence of Hilsa, which is more comprehensive and accurate than previous studies conducted in India (one study) and Bangladesh (two studies).

Besides, RNA sequencing was performed using nine different tissues collected from 14 Hilsa specimens from both riverine and marine environments. This study successfully identified the scientific reasons behind Hilsa’s rich flavor and oil content. All DNA and RNA sequencing data have been stored in the NCBI (National Center for Biotechnology Information) public database for future research purposes.

The research findings indicate that Bangladesh has only a single population of Hilsa, posing a serious existential threat. Any natural disaster or pollution-induced catastrophe affecting this single population could potentially lead to the extinction of Hilsa in Bangladesh.

Dr. Kishore Kumar Sarkar, Lecturer at Shanghai Ocean University, remarked, "Understanding Hilsa’s reproductive process was a challenging endeavor, as it follows distinct reproductive strategies in marine and riverine environments."

Joining the seminar online, Prof Dr. Chinhong Li from Shanghai Ocean University said, "Our research on Hilsa is the result of long-term dedication and hard work.

Addressing the seminar, Prof Dr. Md. Rezaul Karim, Vice-Chancellor of JnU said , "Our researchers have undertaken groundbreaking studies on Hilsa, which deserve great appreciation. I hope these studies will significantly contribute to national policy-making and conservation initiatives."