A joint team of researchers from Shanghai Ocean University and Jagannath University in Bangladesh recently unveiled three groundbreaking research findings on Hilsa shad (Tenualosa ilisha), a flagship species in Bangladesh and its national fish, marking a new milestone of international cooperation in the species' study, management and protection.

These breakthroughs were made by three Bangladeshi researchers, namely Md Rashedur Rahman, Kishor Kumar Sarke and Anirban Sarker, all of whom are PhD graduates from the Lab of Molecular Systematics and Ecology of Shanghai Ocean University. Their research mainly focuses on three landmark studies on Hilsa shad, including its sex reversal, whole genome sequencing, and population genomics.

Notably among them, Rahman, who completed his PhD in Shanghai and returned to his own nation in December, has for the first time proved the sex change phenomenon in Hilsa shad. Through biological and histological analyses on 203 samples from six regions including the Padma River, Meghna River and the Bay of Bengal, his research revealed that this species undergoes protandrous hermaphroditism, meaning individuals transition from male to female at a certain stage of their life cycle.

This discovery provides critical insights into the apparent scarcity of male Hilsa, which has long puzzled researchers and fisheries managers, and provides an important scientific basis for understanding the complete life cycle, reproductive strategies, and sexual transition mechanisms of shad.

"The Hilsa shad, a flagship species in Bangladesh, holds immense economic and ecological value. These findings not only deepen our understanding of the biological characteristics of the Hilsa shad but also provide a scientific foundation for the conservation and sustainable management of this critically important species," said Huang Xuxiong, executive deputy dean of the College of Fisheries and Life Science at Shanghai Ocean University, at a news briefing on Feb 27.

Li Chenhong, a professor at Shanghai Ocean University and supervisor of the lab, pointed out that the research findings are the results of nearly 10 years of hard work made by three classes of Bangladeshi students in countless days and nights.

"We hope that these results will provide a scientific basis for the conservation and sustainable utilization of Hilsa shad, and we also hope that the educational cooperation between the two universities will bear more fruitful results," he said.