Orca uprising - Why are killer whales attacking boats? | DW Documentary

Key Concepts

• Iberian Orcas: A specific population of orcas found in the Strait of Gibraltar and surrounding waters.
• Boat Interactions: Orcas, particularly a group known as the "Barbate group," have been observed ramming and damaging boats, especially yachts, in the Strait of Gibraltar.
• Rudder Damage: A common outcome of these interactions, leading to loss of steering and, in some cases, boat sinkings.
• Cersei: A marine conservation organization researching Iberian orcas.
• FILM (Foundation for Information and Research for the Marine Mammals): An organization founded by Katarina Haya, dedicated to marine mammal research and conservation in the Strait of Gibraltar.
• Orca Database: A collection of identified orcas, cataloged through photo identification, used to track individuals and pods.
• Barbate Group: A specific pod of orcas, primarily composed of juvenile males, known for their interactions with boats.
• Bluefin Tuna: The primary food source for Iberian orcas, whose migration patterns influence orca presence and behavior.
• Amadraba: A traditional fishing method for bluefin tuna.
• Hydrophone: An underwater microphone used to detect orca vocalizations.
• Satellite Transmitter: A device attached to orcas to track their movements and provide data on their behavior.
• Orca Forecast: Predictive models based on satellite data to anticipate orca locations and minimize human-boat interactions.

Orca Interactions in the Strait of Gibraltar

Introduction to the Phenomenon

Since 2020, the Strait of Gibraltar has witnessed an unusual and concerning behavior among its resident orca population: attacks on boats, predominantly yachts. These interactions, numbering in the hundreds, often involve repeated ramming. Skippers like Mark Wendy House have described terrifying encounters, with the sound of splashes triggering anxiety. Ymer Fonbake's crew, participating in an ocean race, experienced a similar event, describing the impacts as feeling like a deliberate attack. These incidents have resulted in significant damage, with many boats losing steering. As of October 2025, eight boats have sunk due to these interactions, though all individuals have been successfully rescued.

Research and Conservation Efforts

Reno de Stefan, president of the marine conservation organization Cersei, has dedicated over 25 years to researching Iberian orcas. His work involves both desk research and at-sea observation. He is actively involved in understanding the reasons behind these boat interactions. His organization, Cersei, aims to explain or at least mitigate the problem.

Scientific Methodology and Data Collection

A key methodology employed by de Stefan's team is fitting orcas with satellite transmitters. This is done using an anesthetic rifle with a specialized arrow containing the tag. The tag is designed to remain in the whale for two to three months, providing daily location data (10-12 positions per day). This information is crucial for understanding where, when, and potentially why these orcas are interacting with boats. The transmitter is precisely aimed at the dorsal fin for optimal attachment. De Stefan also views orcas as "ambassadors of what is happening in the sea," providing insights into climate change.

The Role of FILM and Katarina Haya

Katarina Haya, a Swiss national, founded the marine mammal research and whale watching company FILM (Foundation for Information and Research for the Marine Mammals) in Tarifa in 1998. FILM operates whale watching tours twice daily from Tarifa, heading into the Strait of Gibraltar. Haya is a prominent figure in publicizing the threats to marine animals from increased shipping traffic.

Threats to Marine Life

The Strait of Gibraltar is a vital shipping route, with approximately 120,000 ships passing through annually. This heavy traffic poses significant dangers to marine life. High-speed ferries between Tarifa and Tangier are a particular concern. FILM has documented instances of whales, including fin whales, being fatally injured by ship propellers. Haya has been instrumental in identifying and publicizing the presence of seven different cetacean species in these waters.

Cetacean Diversity in the Strait

The waters of the Strait of Gibraltar are home to a diverse range of whales and dolphins. Katarina Haya notes the most frequently sighted species are pilot whales, followed by bottlenose dolphins, common dolphins, and striped dolphins. Sperm whales are also present, migrating from the Mediterranean to feed in the Strait during spring and summer. Orcas are observed less regularly, typically appearing in July and August, coinciding with tuna fishing seasons. They are considered semi-resident, returning to the area but not year-round.

Orca Identification and Pod Structure

FILM, along with biologist Jose Manuel Escobar Casado, has been actively identifying individual orcas through photo-identification since 1998. This has led to the creation of a valuable orca database. Currently, 35 individuals are identified, divided into six communities. Pods A and B are consistently observed throughout the summer.

The Barbate Group

A particular group, named the "Barbate group" after a nearby port, is singled out for its interactions with sailboats. This group is predominantly composed of boisterous juvenile males. They have been observed examining rudders and propellers of whale watching boats, though they tend to maintain a distance from motorboats, likely perceiving them as more dangerous.

Theories Behind Orca Interactions

Several theories attempt to explain the orcas' behavior towards boats:

• Hunting Instinct and Training: Jose Manuel Escobar Casado suggests that the interactions might be linked to their hunting instinct, with the movement of rudders resembling that of tuna. He has observed orcas playing with sunfish, which are thin and move similarly to tuna.
• Revenge Theory (Gladis Blanca): A circulating theory posits that a female orca named Gladis Blanca (identified as the grandmother of the Barbate group) may have had negative experiences with boats and is now teaching her offspring and grandchildren to attack them. However, Reno de Stefan dismisses this, stating, "The orcas don't revenge. The orcas just eat, play, and make reproduction. They don't have any revenge things."
• Game and Play: Reno de Stefan's research suggests that the interactions could be a form of play, particularly among younger orcas. He observed a significant shift in the orca population structure: in 1999, 70% were juveniles or calves; by 2010, this dropped to 35%; and it has been growing again since 2015. This increase in juveniles is linked to the recovery of tuna stocks after a decline due to overfishing. These new calves, born without siblings, may have had to "invent new games," which include interacting with boats by pushing and breaking rudders. This theory is supported by video evidence showing how easily rudders can be broken.
• Rudder Resemblance: Another theory suggests that the rudder's shape might resemble the dorsal fin of a whale, provoking an interaction.

The Role of Tuna Fishing

The presence and behavior of Iberian orcas are closely tied to the bluefin tuna population. Bluefin tuna migrate from the North Atlantic to the Mediterranean for spawning from May onwards and return from July. This migration coincides with both human fishing activities and orca presence in the Strait.

Orca-Fisherman Interactions

Fishermen, like Captain Pepe Castro Cerudo and mechanic Javi Gabbancho Khano, report that orcas actively steal their catch. The orcas have developed a strategy of waiting for tuna to be hooked and brought near the surface (within 20 meters) before snatching them from the lines. This competition for tuna leads to frustration for fishermen, who lose income. However, fishermen generally do not view the orcas as aggressive or hostile, recognizing that the orcas are also seeking food in their habitat. Videos of orcas stealing tuna are common and often go viral.

Mitigating Interactions and Future Outlook

Reno de Stefan's research, particularly the satellite tracking data, has provided crucial insights for mitigating these interactions.

Safe Passage Routes

Analysis of interaction data reveals that most incidents occur within the Barbate group's preferred hunting grounds. De Stefan's team has identified safe passage routes. By maintaining a depth of approximately 30 meters, boats can avoid these critical areas. This strategy has led to a significant decrease in interactions.

Orca Forecasts and Reduced Incidents

The development of "orca forecasts" based on satellite data has been highly effective. These forecasts allow for the prediction of orca locations, enabling boats to avoid them. This has resulted in a reported decrease of 70-80% in interactions from the previous year. De Stefan emphasizes that all interactions could have been avoided by adhering to these identified safe routes. The hope is that by sticking to these routes, humans and animals can coexist safely, minimizing further conflict.