Thousands of marine species could be at risk if a new United Nations high-seas biodiversity treaty, now being negotiated in New York, does not include measures to address the management of all fish species in international waters, not just the commercial species, warns an analysis by American, Dutch, Swiss and French researchers.

“Of the 4,018 known species of fish in the deep ocean, more than 95% are non-targeted species whose populations are not assessed by regional fisheries management organizations and are currently not being considered as part of the high-seas biodiversity to be monitored and protected under the new treaty,” said Guillermo Ortuño Crespo, a doctoral candidate at Duke University’s Nicholas School of the Environment and lead author of the new analysis.

“We found that only 4.8% of high-seas fish species have stock assessments or analogous forms of population models,” he said. “For more than 85%, we have no information at all on their population trends. We simply don’t know enough to know if or how they are being affected.”

“These findings make a compelling case for covering the full scope of high-seas fish biodiversity in the new agreement,” Ortuño Crespo said.

“We are not arguing that the emerging treaty should infringe on the current management mandate of regional fisheries management organizations, but we are calling for negotiators to address biodiversity concerns for the species that are not currently being managed and are slipping through the governance net,” emphasized Patrick N. Halpin, professor and director of the Marine Geospatial Ecology Lab at Duke’s Nicholas School.

“Fisheries management and the management of overall fish biodiversity are uniquely different processes and activities,” Halpin noted.

Ortuño Crespo, Halpin and their colleagues published their analysis in the journal Nature Ecology & Evolution.

The UN General Assembly has been meeting at its New York headquarters for two weeks to hammer out the final text of the new treaty on marine biodiversity — first proposed almost 20 years ago — under the UN Law of the Sea.

“This is an opportunity of a lifetime to increase the sustainability of human activities in the high seas, which cover 46% of our planet, so we must get it right,” Ortuño Crespo said.

Early in the discussion process, parties to the negotiations agreed that any new treaty should not undermine existing agreements or management organizations. Some nations have used this pretext as a way to exclude already managed commercial fisheries and other human activities from the treaty, Ortuño Crespo said. But by excluding such species, the majority of non-commercial fish species in the high seas might not be effectively managed under the treaty.

Fears that expanding the scope of the treaty to include all fish biodiversity would undermine existing agreements and management organizations are unfounded, he added.

“We believe that the new treaty, with the expanded scope we propose, could help regional fisheries management organizations fulfil their conservation and management mandates, and encourage research, monitoring and management of all forms of biodiversity that are currently not being monitored by existing bodies or treaties,” he said.