By Sharon Atieno Onyango
Fiji and Panama have launched a new global commitment to protect the “twilight zone”, one of the ocean’s most critical ecosystems.
The zone covers an area of 200-1,000 meters (220-1,100 yards) beneath the ocean surface and 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.
Announced at the Our Ocean Conference in Mombasa, Kenya, the 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.
According to Eduardo Carrasquilla, administrator general of the aquatic resources’ authority of Panama, without a healthy, functioning twilight zone, the health of the entire ocean is at risk.
Reiterating Panama’s commitment to safeguarding all ocean layers, Carrasquilla said, “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.”
Sivendra Michael, Fiji’s permanent secretary for environment and climate change, said, “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,”
The Mesopelagic Zone Conservation Challenge is a voluntary initiative of willing governments, with support from conservation organizations, 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 and advancing scientific understanding of the little-understood mesopelagic zone.
They also pledge to establish robust management frameworks to ensure any future activities are sustainable, transparent and consistent with international obligations.
They also commit to 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.
“The twilight zone serves as a gateway between the ocean’s surface and the deep sea,” said Chris Dorsett, Ocean Conservancy’s Vice President of Conservation. “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 Defense Fund. 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% of swordfish diets and 46% of yellowfin tuna diets. With the Kenyan industry reporting $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% 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.
Lance Morgan, president of the Marine Conservation Institute, stresses the importance of the marine life in reducing carbon footprint.
“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,” Morgan explained.
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% 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.
“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,” said Kristin Kleisner, associate vice president of ocean science at Environmental Defense Fund.
“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.”
So far, Portugal and Vanuatu have expressed their support for the overarching goals of the challenge stressing the importance of ocean governance and protecting the ocean’s critical role in regulating global climate.
