Nansen research vessel gathers data for sustainable use and conservation of marine biodiversity

"We went the furthest I have ever been from land. We only saw one ship a week crossing the horizon. There were birds and whales, and apart from that, just ocean, a deep ultramarine-coloured ocean, as far as the eye could see."

Scientist Marco Milardi has taken part in a trip of a lifetime to the international waters of the Southwest Indian Ocean, going where very few people have ever been. He was one of over 20 scientists from 11 countries on the R/V Dr. Fridtjof Nansen, a vessel operated as part of the EAF-Nansen Programme, a partnership between the Food and Agriculture Organization of the United Nations (FAO), the Government of Norway, 33 countries and several regional organizations across Africa and the Bay of Bengal.

Since 1975, when the first Nansen vessel set sail, the Programme's scientific discoveries have been foundational for fisheries and marine research, and the knowledge generated has informed the sustainable use of marine resources in many regions of the world.

It's hard to believe in this day and age, but relatively little is known about international waters and their deep-sea inhabitants. Information about fish stocks, biodiversity and vulnerable marine ecosystems in the high seas is limited. FAO's Review of the state of world marine fishery resources found that for over one third of deep-sea stocks, there is still insufficient information to know their status: whether they are abundant, stable or declining.  

This latest Nansen research voyage was organized by FAO, through its Global Environmental Facility (GEF)- funded Common Oceans Deep-Sea Fisheries project and its EAF-Nansen Programme, together with its partners, the Southern Indian Ocean Fisheries Agreement (SIOFA) and the Institute of Marine Research (IMR) of Norway.

This voyage specifically sought to investigate fisheries resources, map vulnerable ecosystems, identify little-known deep-sea shark species, monitor seabirds and whales and survey a series of underwater mountains known as seamounts, in a wide area of the Southwest Indian Ocean. The mission is part of increasing efforts to gather data that reinforce science-based management in these areas, reconciling the interests of the fishing industry, food security and biodiversity. 

"During this voyage, we studied 3 400 nautical miles across remote seamounts south of Madagascar, using active acoustics to collect new insights into both habitats and key species," says Bjørn Erik Axelsen, IMR scientist and leader of the scientific survey. 

Milardi headed the 'acoustics' research team on the Nansen: "The purpose of the acoustic work was to survey aggregations or schools of certain fish species through an echo-sounder," he explains, noting that this tool detects the fish by measuring the strength of the echoes returning to the ship.

"We'd spend the whole night [acoustically] sweeping a seamount in a search pattern, trying to find the dense concentrations of fish species," he describes.

This painstaking work was aimed at assessing the status of these fish stocks so that SIOFA, the regional fisheries management organization (RFMO) he works for, can decide if fishing that stock is sustainable or not.

Another area of concern is deep-sea sharks, which are often documented only as discarded bycatch from fishing. This reflects the limited knowledge of these species as well as the importance of solid data to better understand marine ecosystems and the potential impact of fishing operations.

"There's a gap in assessing impacts right now. For example, we don't know where many of the deep-sea sharks are in the ocean...This knowledge is key to making sound management decisions," says Anthony Thompson, FAO Deep-sea Fisheries Expert and co-leader for the research voyage.

"If we know where people are fishing and that overlaps with where the sharks live, then we know the sharks are potentially at risk. If there are no overlaps, then there are no impacts," he adds.

In fact, during the voyage, scientists gathered the most complete set of data ever to help assess deep-sea shark populations in the Southwest Indian Ocean high seas. In the process, they captured the first-ever video of a live Dark Mouth Chimaera, a very rare fish found only in these waters, and filmed for the first time, lantern sharks living one kilometre deep in these seas.

They also videoed vulnerable marine ecosystems 50 meters to 1 000 meters in depth, focusing on communities of deep-sea corals and sponges. "These habitats are actually quite rare, patchy and localized, so we need to know where they are to be able to safeguard them," states Thompson.

"This information all strengthens the science available to help RFMOs manage species, for example the shark catches as bycatch, and also bottom fishing," he summarizes.

For his part, Milardi states that the high-quality data generated in voyages such as these helps build acceptance of the measures designed to safeguard marine ecosystems while allowing responsible fisheries. This increases "support of fisheries management decisions from the public, the fishing industry, pretty much everyone involved," he adds.

Over the past decade, FAO has made significant progress in strengthening the scientific data in Areas Beyond National Jurisdiction (ABNJ), those areas of the ocean that do not fall under the sovereignty of any single nation. These surveys support the sustainable use and conservation of marine biodiversity in international waters in line with the Biodiversity Beyond National Jurisdiction (BBNJ) Agreement.

The samples collected and information gathered during the cruise will be analysed over the coming years by SIOFA's scientific committee. "Projects like these contribute to strengthening cooperation and regular exchange with RFMOs to address shared issues," adds Vera Agostini, FAO Deputy Director of the Fisheries and Aquaculture Division. "Over time the knowledge they generate will build a solid scientific basis for more effective fisheries management, supporting the long-term conservation of biodiversity in this and other regions."

The story and photos can be found here: https://www.fao.org/newsroom/story/a-voyage-to-know-the-unknown-in-international-waters/en