In the dark months of November to January, the fjords around Skjervøy and neighbouring Troms waters transform into a stage for one of the world's most reliable large-whale spectacles. Overwintering Norwegian spring-spawning herring (sild) mass in these deep, sheltered inlets, attracting aggregations of killer whales (spekkhogger) and humpback whales (knølhval) that follow the shimmering shoals. For wildlife enthusiasts, this is a rare chance to observe two apex predators employing contrasting hunting strategies within the same Arctic arena.
The Herring: Winter Fuel for Giants
The Norwegian spring-spawning herring is a keystone species in the Northeast Atlantic. After summer feeding in the Barents Sea, the herring migrate south and west to overwinter in fjords along the Norwegian coast, with Skjervøy and the surrounding Troms region serving as a primary wintering ground. These dense, silvery shoals can stretch for kilometres, creating a massive, high-energy food source that draws whales from afar.
For the whales, the herring represent a concentrated lipid-rich meal that is essential for building fat reserves before the leaner months. The herring's behaviour—forming tight balls when threatened—is both a defense and a vulnerability. It is this very behaviour that the whales exploit, and it sets the stage for the dramatic feeding events observed each winter.
Killer Whales: Coordinated Hunters
Orcas in Norwegian waters are specialists in herring hunting, and they have developed a remarkable technique known as 'herding' or 'carousel feeding.' Working in coordinated groups, they use their tails to slap the water's surface, creating a wall of sound and pressure that forces the herring into a tight, dense ball near the surface.
Once the ball is compressed, the orcas take turns swimming through it, stunning the fish with powerful tail strikes before consuming them. This cooperative behaviour is passed down through matrilineal family groups, and each pod may have its own subtle variations. In Skjervøy, observers can witness these intelligent predators communicating with sharp whistles and echolocation clicks as they execute their strategy with military precision.
Humpbacks: The Bubble-Net Specialists
While orcas rely on teamwork and tail-slapping, humpbacks bring a different, equally spectacular technique to the table: bubble-net feeding. A single humpback or a small group will dive beneath the herring shoal and release a curtain of bubbles in a spiral pattern, encircling the fish and forcing them upward into a tight, confined mass.
Then, with mouths wide open, the humpbacks lunge upward through the centre of the net, engulfing thousands of litres of water and herring in a single gulp. This method is energy-intensive but highly efficient, and in the herring-rich fjords of Troms, humpbacks can be seen repeating this behaviour multiple times in a single day, often in the company of gulls that swoop in to snatch any fish that escape.
A Shared Feast: Interspecific Interactions
The presence of both orcas and humpbacks in the same fjords raises questions about competition and coexistence. While they target the same prey, they often feed at different times or in different parts of the fjord, reducing direct conflict. However, there are occasions when the two species interact, with humpbacks sometimes following orcas to take advantage of their herding efforts.
These interactions are generally peaceful, but they can be tense. Orcas are known to sometimes displace humpbacks from prime feeding spots, and humpbacks may respond with tail slaps or loud blows. For researchers, these encounters provide valuable insights into the social dynamics of two of the ocean's top predators sharing a finite resource.
Observing Respectfully: Guidelines for Wildlife Watchers
The winter whale spectacle around Skjervøy is a magnet for wildlife enthusiasts, but it is crucial to observe these animals without causing disturbance. Norwegian regulations and ethical guidelines stipulate that boats must maintain a safe distance—generally at least 200 metres from whales—and should never chase, encircle, or cut off their path.
When whales are actively feeding, it is especially important to reduce speed and noise, as underwater sound can disrupt their hunting. The use of drones is heavily restricted, and landing on islands or disturbing resting animals is prohibited. By following these guidelines, visitors can ensure that the whales continue to return to these fjords for generations to come, and that the spectacle remains a wild, unscripted encounter.
About Lars Haugen
Lars Haugen is a field ornithologist and writer from Trondheim. He has led birdwatching tours in Trøndelag for over ten years and writes about birds, equipment, and great locations in Norway.