September is a time for end-of-summer traditions, whether it is a back-to-school ritual or one last camping trip to soak up the last of the summer sun. In the Arctic, the end of summer is marked by a very ordinary event: the sea ice minimum. One day this month, more Arctic sea ice will form than melts. And the annual pattern of increased Arctic sea ice will begin, culminating in ice packs that stretch from the Central Arctic Ocean to the coastal seas along the shores of Russia, Canada, Alaska, Greenland and Norway.
People have lived along the shores of the Arctic Ocean for thousands of years. Arctic residents are very familiar with this pattern of sea ice melting in the warmer season and refreezing in the cold months. In fact, Arctic ecosystems, marine wildlife and people are organized around this annual cycle.
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What’s quite extraordinary, however, is where this freezing is starting: much nearer to the North Pole than the coasts. That’s because the Central Arctic Ocean—covered in sea ice year-round for much of my lifetime—now features increasing amounts of open water at the end of the Arctic summer.
The Central Arctic Ocean, 1.1 million square miles of international waters surrounding the North Pole, lies at the heart of the Arctic. Yet until sea ice began its unprecedented retreat, it was completely covered in ice year-round. In 2007, even Arctic experts were caught by surprise when they discovered 40% of it was open water in September. The same occurred in 2012. Other years varied widely from low to high.
The precise number for lowest sea ice extent in 2024 will be determined after the fact when all the satellite measurements are in. But looking at daily numbers through today, 2024 won’t be the lowest on record—maybe “just” the sixth lowest. Yet, we can see the bigger picture when we look across multiple years of data. In the last 10 years, for example, an average of 20.5 % of the Central Arctic Ocean was open water in September. This is the highest amount in the satellite record which showed less than 1% as open water in the decades before 1994.
As interesting as they are, these numbers do not adequately describe how radical a shift this represents for the Arctic Ocean and for human interactions with it.
High seas are defined as parts of the ocean beyond 200 nautical miles of coasts. Although most high seas areas are much less studied and understood than coastal seas, the Central Arctic Ocean stands out as one of the least understood marine environments on Earth. As we learn more, we are realizing that it is also one of the most important.
Expeditions have mapped new deepwater corals and seamounts, discovered new species of plankton found nowhere else on Earth, and found much more biological activity beneath the ice in winter than scientists ever expected. Measurements have confirmed that the Central Arctic Ocean is the world’s quietest ocean. And new studies confirm that changes to Arctic sea ice contribute to alteration of the jet stream, leading to more extreme weather events thousands of miles away.
While high seas areas have slowly become subject to some codes of conduct for human behavior, the sudden (on a geological scale) melting of sea ice creates a new risk. Industries and nations interested in the Central Arctic Ocean will arrive ahead of both science and common sense rule-making.
Arctic coastal nations are asserting ownership of more than 95% of the seabed underlying the Central Arctic Ocean—meaning deep-sea mining could occur. And the Central Arctic Ocean has been proposed as a shortcut for industrial goods to connect factories to global markets along a Transpolar Shipping Route. Yet no adequate knowledge or rules are in place for either of these industries to operate safely in such an extreme and globally important place.
When faced with a similar threat to the Central Arctic Ocean from the potential start of commercial fishing, the global community negotiated an international agreement to place a binding moratorium on high-seas fishing in the Central Arctic Ocean. This agreement established a multinational cooperative research program, recognized the special relationship Arctic Indigenous peoples have to the Arctic and ensured their active participation in implementation of the agreement. Coming into force in 2021, the ten signatory countries are now planning joint research using science and Indigenous Knowledge to better understand the Central Arctic Ocean.
As the Arctic days shorten, sea ice is beginning to grow again. But if we want our children to understand this very ordinary cycle in the Arctic, we need to take extraordinary action to protect the Central Arctic Ocean. Learn more about what Ocean Conservancy is doing to protect this global treasure.
The post Protecting the Central Arctic Ocean appeared first on Ocean Conservancy.
After a slight delay of the Maria S. Merian caused by late-arriving containers our research cruise MSM142 finally got underway. By last Tuesday (24.03.2026), the full scientific team had arrived in Nuuk, the capital of Greenland, and the ship reached port on Wednesday (25.03.2026) morning. That same day, scientists and technicians moved on board and immediately began preparations, assembling and testing our instruments. Although the mornings on Wednesday and Thursday were grey and overcast, the afternoons cleared up beautifully. This gave us valuable time to organize equipment on deck and store empty boxes back into the containers before departure.
Given the forecast of harsh conditions outside the fjord, we carried out the mandatory safety drill while still in harbour. This included practicing emergency procedures and boarding the lifeboat. After completing border control, we were finally ready to leave Nuuk. We set sail on March 27th, heading into the Labrador Sea to begin our mission. Even before starting scientific operations, we tested the setup for deploying our gliders without releasing them during the transit out of the fjord. Once we reached open waters, we were met by high waves the following morning. For some on board, this was their first experience under such rough sea conditions. Seasickness quickly became a challenge for a few, while scientific work had to be temporarily postponed due to the strong winds and sea conditions. Together with the crew, we discussed how best to adapt our measurement plans to the given weather conditions. On March 29th, we were finally able to begin our scientific program with the first CTD deployment. A CTD is an instrument used to measure conductivity, temperature, and depth, which are key parameters for understanding ocean structure.
During the following night, we continued with additional CTD stations and successfully recovered two moorings: DSOW 3 and DSOW 4, located south of Greenland. These moorings carry instruments at various depths that measure velocity, temperature, and salinity. DSOW 4 was redeployed on the same day, while DSOW 3 followed the next day. In addition, the bottles attached to the CTD’s rosette can be used to collect water samples from any desired depth. These samples can be used, for example, to determine the oxygen content, nutrient levels, and organic matter.
Both are part of the OSNAP array, a network of moorings spanning the subpolar North Atlantic. On these moorings are a few instruments, for example microcats which measure temperature, pressure and salinity.
We then conducted around 25 CTD stations spaced approximately 3 nautical miles apart across an Irminger ring identified from satellite data. This high-resolution sampling was necessary to capture the structure of an Irminger Ring, which had a radius of about 12 km wide.
The days leading up to April 2nd were marked by very rough weather conditions. Life on board became both challenging and, at times, unintentionally entertaining sliding chairs were not uncommon. During the night from April 1st to April 2nd, winds reached 11 Beaufort with gusts up to 65 knots, forcing us to pause our measurements. Fortunately, conditions improved by morning, allowing us to resume our work. As well as with the help of the crew we had to adapt to the harsh weather conditions to continue our scientific work. On the 3rd of April, we were able to deploy a few gliders and one float. An ocean glider is an autonomous underwater Vehicle, which you can steer remotely and send to different locations, while it is measuring oceanographic key parameters.
This research cruise focuses on understanding small-scale processes in the ocean and their connection to the spring bloom, an essential phase in marine ecosystem in subpolar regions. Despite the challenging start, we have already gathered valuable data and look forward to the weeks ahead in the Labrador Sea.
Despite their dramatic name, false killer whales aren’t an orca species. These animals are dolphins—members of the same extended family as the iconic “killer whale” (Orcinus orca). Compared to their namesake counterparts, these marine mammals are far less well-known than our ocean’s iconic orcas.
Let’s dive in and take a closer look at false killer whales—one of the ocean’s most social, yet lesser-known dolphin species.
Appearance and anatomy
False killer whales (Pseudorca crassidens) are among the largest members of the dolphin family (Delphinidae). Adults can grow up to 20 feet long and weigh between 1,500 and 3,000 pounds, though some individuals have been recorded weighing even more. For comparison, that’s roughly double the size of a bottlenose dolphin—and slightly larger than a typical sedan.
These animals are incredibly powerful swimmers with long, torpedo-shaped bodies that help them move efficiently through the open ocean in search of prey. Their skull structure is what earned them their name, as their head shape closely resembles that of orcas. With broad, rounded heads, muscular jaws and large cone-shaped teeth, early scientists were fascinated by the similarities between these two marine mammal species.
Although their heads may look somewhat like those of orcas, there are several ways to distinguish false killer whales from their larger namesake counterparts.
One of the most noticeable differences has to do with their coloration. While orcas are known for their iconic black-and-white pattern with paler underbellies, alternatively, false killer whales are typically a uniform dark gray to black in color—almost as if a small orca decided to roll around in the dirt. If you’ve ever seen the animated Disney classic 101 Dalmatians, the difference is a bit like when the puppies roll in soot to disguise themselves as labradors instead of showing their usual black-and-white spots.
Their teeth also present a differentiator. The scientific name Pseudorca crassidens translates almost literally to “thick-toothed false orca,” a nod to their sturdy, cone-shaped teeth that help these animals capture prey. Orcas tend to have more robust, bulbous heads, while false killer whales appear slightly narrower and more streamlined.
Behavior and diet
False killer whales are both highly efficient hunters and deeply social animals. It’s not unusual to see them hunting together both in small pods and larger groups as they pursue prey like fish and squid.
Scientists have even observed false killer whales sharing food with each other, a behavior that is very unusual for marine mammals. While some dolphin and whale species work together to pursue prey, they rarely actively share food. The sharing of food among false killer whales spotlights the strong social bonds within their pods. Researchers believe these tight-knit social connections help false killer whales thrive in offshore environments where they’re always on the move.
Maintaining these close bonds and coordinating successful hunts requires constant effective communication, and this is where false killer whales excel. Like other dolphins, they produce a variety of sounds like whistles and clicks to stay connected with their pod and locate prey using echolocation. In the deep offshore waters where they live, sound often becomes more important than sight, since sound travels much farther underwater than light.
Where they live
False killer whales are highly migratory and travel long distances throughout tropical and subtropical waters around the world. They prefer deeper waters far offshore, and this pelagic lifestyle can make them more difficult for scientists to study than many coastal dolphin species.
However, there are a few places where researchers have been able to learn more about them—including the waters surrounding the Hawaiian Islands.
Scientists have identified three distinct groups of false killer whales in and around Hawaii, but one well-studied group stays close to the main Hawaiian Islands year-round. Unfortunately, researchers estimate that only about 140 individuals remained in 2022, with populations expected to decline without action to protect them. This is exactly why this group is listed as endangered under the U.S. Endangered Species Act and is considered one of the most vulnerable marine mammal populations in U.S. waters.
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Current threats to survival
False killer whales are currently listed as Near Threatened on the IUCN Red List. From climate change-induced ocean acidification and harmful algal blooms to marine debris and fishing bycatch, false killer whales face the same mounting pressures that are impacting marine ecosystems around the world. As their prey becomes scarce due to increasing threats, populations of top predators like these decline, serving as a powerful signal that the ocean’s overall health is in critical need of protection.
Here at Ocean Conservancy, we’re working daily to confront these threats head-on and protect the ecosystems and wildlife we all cherish so dearly. But we can’t do it without you. Support from ocean lovers is what powers our work to protect our ocean, and right now, our planet needs all the help it can get. Visit Ocean Conservancy’s Action Center today and join our movement to create a better future for our ocean, forever and for everyone.
The post All About False Killer Whales appeared first on Ocean Conservancy.
https://oceanconservancy.org/blog/2026/03/31/false-killer-whales/
A lot has happened in the meantime: I became an Associate Professor at the University of Southern Denmark, we all lived through the Corona period, then slowly adjusted to the post‑pandemic stability, only to find ourselves again in turbulent political times. I am now affiliated with the Marine Research Center in Kerteminde, a beautiful coastal town on the island of Fyn. My plan is to share small updates on my research and activities every now and then. So let’s start with yesterday’s sampling trip for benthic phytoplankton, carried out by my colleague, Prof. Kazumasa Oguri. The sampling will help prepare for the first‑semester bachelor students who will join his small but fascinating project. This project is all about the benthic diatoms that form dense, photosynthetic communities on tidal‑flat sediments. Their daytime oxygen production enriches the sediment surface and allows oxygen to penetrate deeper, supporting diverse organisms that rely on aerobic respiration. The project will explore how oxygen distribution and oxygen production/consumption in sediments change under different light conditions (day, night, sunrise/sunset). The team will incubate benthic diatom communities in jars and measure oxygen profiles using an oxygen imaging system under controlled light regimes.
Yesterday, we visited several potential sampling sites where students can carry out their fieldwork. I encourage all PIs in our group to define at least one small project related to Kerteminde Fjord, where our laboratories are located. Over time, I hope we can build a more integrated dataset describing the marine and coastal ecosystems of the area.
Another activity currently in preparation is a project on marine invasive species in Kerteminde, which will feed into a course I will run in July and a master’s thesis project. More will come later.
Let’s hope for a more continuous blog from here on, keeping track of our activities, with or without jellyfish!
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