New Mesopelagic Zone Conservation Challenge Calls for Better Stewardship of the Ocean’s Food Warehouse and Carbon Pumpce
At the Our Ocean Conference today, Fiji and Panama launched a new global commitment to protect one of the ocean’s most critical ecosystems.
Spanning the area 200-1,000 meters (220-1,100 yards) beneath the ocean surface, the “twilight zone” is home to an abundance of marine life that serves a central role in the ocean’s food web and helps to regulate the world’s climate.
The newly announced Mesopelagic Zone Conservation Challenge calls on countries to take concrete steps to protect the zone from emerging threats like fishing and deep-sea mining and fill knowledge gaps about this still-mysterious ocean layer.
‘The twilight zone serves as a gateway between the ocean’s surface and the deep sea,” said Ocean Conservancy’s Vice President of Conservation Chris Dorsett.
“Under threat from climate change, growing commercial interests for the production of fish meal and health supplements, and other activities, this ocean layer urgently deserves a spotlight. By pledging to protect and study the mesopelagic zone, Fiji and Panama are setting a model for the world to follow.”
Ocean Conservancy is leading the initiative with the Marine Conservation Institute and Environmental Defence Fund. Whales, dolphins, seabirds, sharks and fishes feast on species from the twilight zone.
Commercially valuable species like tuna and swordfish are particularly dependent on marine animals like lanternfish, squid and shrimp populating this ocean layer. With improving technology and increasing demand for fish protein, industries are exploring ways to exploit these deep-sea animals for uses like fish oil and pet food.
“Without a healthy, functioning twilight zone, the health of the entire ocean is at risk,” said Eduardo Carrasquilla, administrator general of the aquatic resource’s authority of Panama.
“Panama is fully committed to safeguarding all ocean layers — from the surface to the deepest trenches. Protecting the mesopelagic zone doesn’t just protect biodiversity and an important food source. It also helps the ocean to lock away carbon, making it an action we all must stand behind”.
“As a Pacific island state deeply dependent on healthy marine ecosystems, Fiji strongly believes in the critical importance of protecting the ocean twilight zone for the long-term health of our ocean and the well-being of Pacific communities,” said Sivendra Michael, Fiji’s permanent secretary for environment and climate change.
Ocean Conservancy analysis found that the mesopelagic zone is the primary food source for Kenya’s tuna and swordfish fisheries. In particular, species from the twilight zone make up as much as 81 percent of swordfish diets and 46 percent of yellowfin tuna diets. With the Kenyan industry reporting US$3.3 million in earnings in 2023 and supporting hundreds of local fishermen, the depletion of these species would have serious impacts on local incomes.
The twilight zone comprises just 20 percent of the ocean’s volume, but by some estimates is home to upwards of 90% of the ocean’s fish biomass. This means that if you were to measure all of the marine life in this layer together on one scale, they would weigh far more than all the animals in the rest of the ocean put together.
‘Marine life in the twilight zone does more than provide food,” said Lance Morgan, president of the Marine Conservation Institute. “Everyday, billions of mesopelagic animals migrate to the surface to feed, transporting carbon back down, creating the ocean’s biological carbon pump. They transfer an estimated two to six gigatons of carbon per year from the surface to the deep sea, on the low end, an amount equivalent to double the emissions produced annually by all cars worldwide. Most of this carbon stays in the twilight zone or sinks even deeper, reducing atmospheric CO₂.”
Populations of commercially important small fish such as anchovies are expected to decline in a changing climate, driving the fishing industry to look at other alternatives such as those species found in the mesopelagic zone. Lanternfish, smaller than a pencil but rich in omega-3 fatty acids, have emerged as an attractive substitute for use in aquaculture, pet food, and human health supplements. They currently account for 60 percent of all deep-sea fish, with a total biomass of approximately 600 million tons across the ocean. Beyond fishing pressure, the zone faces additional threats from climate change, including warming waters and deoxygenation, and from the prospect of deep-sea mining.
Kristin Kleisner, associate vice president of ocean science at Environmental Defence Fund, said, “What’s so alarming about the increased commercial interest in the twilight zone is that we still have so much to learn about this part of the ocean and the unique ecosystems it contains. We have only cataloged a fraction of the species living in this layer, and we don’t fully understand their role in ocean food webs and the ocean’s carbon cycling, but we know enough to know that protecting this zone is essential for a healthy ocean and a thriving planet.”
Portugal and Vanuatu Express Support for the Challenge
In addition to Panama and Fiji officially joining the challenge, Portugal and Vanuatu recognised the importance of the mesopelagic zone and expressed their support for the overarching goals of the challenge.
“Portugal is a maritime nation, by geography, by history, and by heart,” said Salvador Malheiro, Portugal’s secretary of state for fisheries and maritime affairs.
“Leading by example is the only effective way to advance international ocean governance. We look forward to working closely with partner nations to turn the goals of the Mesopelagic Zone Conservation Challenge into regular ocean management.”
“The mesopelagic zone is not only a reservoir of biodiversity — it is also central to the ocean’s role in regulating the global climate, transferring significant amounts of carbon to deep waters each year,” said Samson Vilvil Fare, director general of Vanuatu’s ministry of fisheries, oceans and maritime affairs. “Protecting this function is critical for the future of our planet.”
The Mesopelagic Zone Conservation Challenge
The Mesopelagic Zone Conservation Challenge is a voluntary initiative of willing governments, with support from conservation organisations, research institutions and other groups engaged in protecting the twilight zone. Participating governments commit to:
*Applying a precautionary approach to the expansion of fishing and other potentially harmful activities targeting or impacting twilight zone species.
*Advancing scientific understanding of the little-understood mesopelagic zone.
*Establishing robust management frameworks to ensure any future activities are sustainable, transparent and consistent with international obligations.
*Advocating for the inclusion of language recognizing the importance of the mesopelagic zone and the need for a precautionary management approach in relevant decision documents, including the United Nations General Assembly Sustainable Fisheries Resolution.
