There is still much to learn about the fin whales which inhabit waters off the coast of Spain.
It had been thought that these migratory cetaceans only spent part of their time in the Western Mediterranean but marine biologists now believe that some of the fin whales are here all year round.
The second-largest animal on the planet after the blue whale, the fin whale grows up to 25 metres in length, weighing around 90 tonnes.
This gentle giant of the seas is being studied by organisations from different areas of Spain.
The polytechnic university of Valencia (UPV) operates the CaboRorcual project, with the ‘rorcual común’ being the Spanish name for the fin whale.
Principal scientific investigator Eduardo Belda explained they are studying the origin and presence of fin whales off Jávea’s Cabo de la Nao and in the Ibiza channel.
“Using passive acoustic monitoring techniques, we’ve detected that the fin whale might be present year round, not just during the summer months, although sightings are more frequent in June and July,” said Sr Belda.
The objective of this multidisciplinary research project, underway since 2021, ‘is to analyse the populations of fin whales that migrate past Cabo de la Nao and identify where they are headed’, he added.
Sr Belda noted that in two years of study they observed around 150 fin whales passing the coasts of Denia and Jávea between the months of April and October, swimming south.
A transmitter fitted to one of the whales recorded that it passed along the coast of Alicante in the summer and migrated to the Atlantic.
In addition to providing information on the movements and migratory routes followed by these animals, they can evaluate risks for the conservation of this species, in particular, associated with maritime traffic and underwater noise.
Measures are being studied to reduce the possibility of collisions with boats.
Further north
SUBMON, an NGO which is dedicated to conserving and raising awareness of the marine environment, has been studying fin whales from Cataluña, in the northern part of the ‘Mediterranean cetacean migration corridor’.
They explain that the corridor is a 46,385 km2 marine protected area, comprising waters of great ecological value between mainland Spain and the Balearic Islands.
It is ‘of vital importance for the survival of cetaceans in the Western Mediterranean’.
SUBMON assert that two distinct sub-populations of fin whales exist.
The ‘resident whales’ move around the central and north-western Mediterranean, they state; while the Atlantic population arrive through the Strait of Gibraltar between November and April, then return to the Ocean between May and October.
The waters off Cataluña ‘present high productivity in the spring’ and are generally full of food for the whales.
Their migrations are generally based on the availability of small invertebrates such as krill, although exceptions are being found to this ‘rule’ as knowledge of the species increases.
SUBMON states that the Mediterranean sub-population consists of at least 10,000 mature individuals.
However, they emphasise that fin whale numbers are ‘continuously declining’.
“In fact, the Mediterranean sub-population is classified as endangered on the IUCN Red List,” they note.
SUBMON admit that they still do not know where fin whales reproduce; or the exact areas occupied by the two different sub-populations, or how much they interact.
In order to work on the conservation of these species, it is also essential to know the impact level of the different threats in the area, they assert.
“It is currently known that the Mediterranean is one of the most polluted natural environments by plastic litter and that this represents one of the greatest threats to marine life, but quantitative studies of floating litter are needed to allow a correct evaluation of this problem,” says SUBMON.
Their project ‘will help to improve knowledge of the species and threats in the area’.
Denia sightings
The 2024 summer observation programme from the coast of Denia recorded 61 fin whales passing south by July 8.
Coastguard spokesman in Denia, Toni Martínez, said fin whales swim up to the south Ligurian Sea, off Italy, to feed; then, in the spring, they migrate south.
The whales can be spotted from the capes of San Antonio and de la Nao, he added.
A town hall spokesperson explained that the fin whale is the largest animal inhabiting the Mediterranean Sea and it ‘plays a fundamental role in the functioning of the ecosystem, mobilising nutrients’.
Sr Martínez said more whales have been observed in the last 15 years because ‘many more pairs of eyes are watching’.
The migration of the Atlantic fin whales sees them go through the Strait of Gibraltar and head up the west coast of the Iberian Peninsula, passing Portugal and Galicia to reach the Cantabrian Sea.
The UPV’s Eduardo Belda said: “There are many questions which need to be answered, such as how many Mediterranean fin whales migrate to the Atlantic and when exactly they come back, and if they reproduce at this time, and where they feed from the autumn to the spring.
“As it is the largest animal that we have in the small Mediterranean, it is surprising how little we know about it.”
He added that sometimes the whales come so close to the coast that they came be seen from the terraces of restaurants in Les Deveses or Las Rotas.
“People are able to experience the joy of seeing these whales,” he said.
Fin whale facts
It has an elegant, aerodynamic body with a V-shaped head.
The fin whale has a high falcate dorsal fin, located approximately on the back third of the body.
It has a distinctive colour pattern: the back and sides of the body are black or dark-brownish grey, and the belly is white.
The lower jaw has a unique asymmetrical pattern; it is dark on the left side and white on the right side.
It blows vertically, to a height of between four to six metres.
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