Beginning in 2013, DBRF researcher Paul Clerkin initiated a long-term deep-sea research program in the Southern Indian Ocean, operating from commercial fishing vessels departing from Mauritius. This project has been ongoing for over a decade and, unlike conventional research cruises, these expeditions are embedded directly within commercial fishing operations. Paul lives aboard fishing vessels for weeks to over a month at a time, documenting and studying deep-sea organisms brought up incidentally as bycatch from extreme depths. This approach provides rare access to species that are otherwise almost impossible to sample using traditional scientific platforms.

Throughout both expeditions, hundreds of deep-sea fishes and sharks were systematically photodocumented, measured, and identified—many representing new or poorly described species. When possible, animals were recorded and released alive. When survival was not possible, DBRF collected tissue samples and voucher specimens for genetic, anatomical, and taxonomic study, ensuring that unavoidable bycatch contributed directly to scientific knowledge.

These collections have proven critical for:

• Describing previously unknown deep-sea species

• Expanding reference material for global taxonomic databases

• Improving understanding of deep-water biodiversity and biogeography in the South Indian Ocean

By working directly alongside fishers, DBRF’s Southern Indian Ocean program demonstrates how collaboration with industry can transform unavoidable bycatch into high-value scientific data, while laying the groundwork for improved conservation and management of deep-sea ecosystems.