The small population of Iberian orcas (Iberian killer whales) which lives off the coast of Spain is listed as critically endangered by the International Union for Conservation of Nature (IUCN).
Only 37 individuals were counted in 2023.
The orca is an intelligent and sociable marine mammal which inhabits waters between the Strait of Gibraltar and the Bay of Biscay, notes the ministry for the ecological transition.
Orcas ‘organise themselves in stable social groups’ and follow populations of bluefin tuna, which are essential for their survival.
This large migratory fish is the mainstay of their diet.
Where are they?
Members of the dolphin family, orcas are mainly found in waters between 30 metres and 200m in depth, with occasional observations in deeper waters, apparently linked to the presence of tuna fishing vessels (often associated with depredation).
They are seen mostly between February and July in the waters off Barbate (west of Strait of Gibraltar) and nearby areas, dispersing from July to various other locations, including Belle Île in France, Brest, waters off Cap Breton, Galicia, the entire Portuguese coast and the Strait of Gibraltar.
The orcas previously employed a resistance-exhaustion foraging technique, chasing tuna at high speed to induce exhaustion to facilitate capture, according to scientists who have studied the Iberian orcas.
More recently, observations indicate these pursuits only last for two to three minutes.
“In discussion, it was noted that the change in foraging strategy may be the result of bluefin tuna recovery; the increased presence of tuna could allow the whales to expend less effort than during the period 2005–2011, when there were fewer tuna,” say the scientists.
“In addition, climate change could be playing a role, leading to these tuna being in the Gulf of Cádiz continuously rather than seasonally.
“This year-round abundance means that there appears to no longer be a need for the whales to pursue every fish encountered.”
Boat interactions
The Iberian population gained notoriety at the beginning of this decade when they started ‘interacting’ with vessels off the Atlantic south coast of Spain.
During these incidents, they rammed the rudder ‘often damaging and even breaking it, rendering the boat unnavigable, and requiring a rescue by local coast guards’.
Since 2021, interactions have resulted in the sinking of six vessels, which were four sailing boats and two fishing boats, according to the ministry.
Due to the incidents, the Spanish and Portuguese governments organised an international workshop in Madrid last year, involving scientists and management authorities,
Following the discussions the scientists produced a report about the Iberian orca, along with recommendations.
They noted that the population was stable from 2011 to 2023.
However, they agreed that the ‘low absolute abundance and the decrease in adult female survival rates were of serious concern, given the variety of direct and indirect threats facing them and their habitat’.
“Aggressive responses by some mariners to interactions with Iberian killer whales are a new, important threat that emphasises the need to find practical solutions to the issue as soon as possible,” they added.
The scientists said long-term monitoring of the Iberian orcas is necessary and highlighted that, although food shortages are no longer an issue after the recovery of bluefin tuna in the region, fishing still poses a threat through entanglements and fisher reactions to depredating whales.
“The future of the population depends on survival and recruitment of juveniles and the survival of reproductive females,” they added.
The scientists made a number of recommendations, including the importance of fully understanding the causes of death of orcas from this critically endangered population.
They advised improving stranding responses throughout the population’s range to maximise the number of complete, rigorous necropsies of any individuals found.
They strongly recommended that all existing datasets, such as photo-identification, sightings and genetics, be consolidated and that all researchers in the region work in close cooperation and communicate frequently regarding their movements and behaviour.
Sailors take note
Their listing on the IUCN Red List means that deterrence measures that might cause immediate harm to the orcas or affect long-term survival or reproduction are illegal under European Union and national laws.
According to the scientists, several of these harmful measures have been in use at some level since interactions were first reported in the summer of 2020; and include use of firecrackers and electrocution.
Despite the use of these illegal measures, the orcas continued the interactions.
“Thus, they are not only ineffective but may be reinforcing the behaviour and increasing the severity of damage to vessels,” say the scientists.
The scientists recommended that mariners only use methods with no impact on the whales or the environment (e.g. moving away), until research and testing determine the effectiveness and safety of other potential measures.
They say the interactions are not attacks on boats.
“The singular agreement amongst the experts at this workshop is that the interactions between Iberian killer whales and vessels are not aggressive,” they noted.
“The interactions have more elements consistent with fad behaviour or play/socialising than aggression.
“The use of such terms as ‘attack’ to describe these interactions is thus inappropriate, misleading and should cease.”
Despite this, the workshop recognised that this behaviour is often frightening for mariners and results in actual damage to rudders and even the sinking of vessels on occasion.
Whatever the motivation, ‘it is therefore imperative to provide timely advice to mariners on actions that they might take to avoid interactions or minimise their impact should they occur’ whilst ensuring the welfare of the orcas.
“These are intelligent, socially complex, innovative wild animals and science cannot predict their behaviour with certainty,” they added.
Advice for mariners
The Spanish government has advised that vessels travel around rather than through orca hotspots (see map).
Scientists recommend, in the event of an encounter, that mariners move away from the orcas as quickly as possible, at least 2 to 3km from the area in which the whales were encountered.
Moving away is not guaranteed to end the interaction or prevent damage, but may reduce the latter’s likelihood, they note.
Mariners should alert authorities as soon as an encounter begins, which should help with response time for a rescue if needed.
The scientists strongly recommended that mariners do not use any measures that would harm the whales.
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