The blue shark (Prionace glauca) is classed as being in critical danger of extinction in the Mediterranean, according to the International Union for Conservation of Nature (IUCN).
It is a fish which spends most of its life in the open sea at depths of between 60 and 300 metres, reveals National Geographic, preferring temperatures of between 8ºC and 21ºC.
Despite this, in recent years there have been more sightings close to the shore of Spain’s Mediterranean coast, with different theories put forward as to why this is happening.
A couple of days ago a large blue shark was filmed in shallow water in the port of L’Ampolla in Tarragona province.
The town hall reported that ‘everything points to the fact that it became disorientated’.
At the same time they called for ‘calm’ on social media and said they were ‘in contact with the relevant services to guarantee the welfare of the animal’.
They added that the blue shark is a protected species which is important for the balance of marine ecosystems.
Valencia region
Marine biologists from the Oceanogràfic sea life centre in Valencia have been called out on a number of occasions in recent years to rescue blue sharks.
The Oceanogràfic commented that they usually approach shallow water when they are ill or injured. However, this has not always been the case in the last five years.
In August, 2021 during peak holiday season, a 2.5-metre-long blue shark appeared at Playa de Poniente in Benidorm, causing a commotion on the packed beach.
It was swimming in very shallow water along the shore.
A team from the Oceanogràfic foundation attended and evaluated the health of the 80-kilo female after immobilising her.
They found that she was in ‘optimum’ condition and were able to take her out into deep water to release her.
At the time they noted that the approach could have been caused by her ‘reproductive behaviour’.
A similar incident occurred in November, 2022 at the Real Club Náutico harbour in Valencia (see photo), where 2.5-metre-long blue shark was observed in shallow water.
Oceanogràfic biologists immobilised the fish and carried out tests, which showed it was in good health, but thinner than it should have been.
They stated that it had probably become disorientated during stormy weather. The shark was towed out to deeper water and released.
Warmer seas
National Geographic reported that scientists have found that the heating of the seas is ‘leading to migratory movements of many species’ and changes to their habits.
The fact that blue sharks have appeared along the coast is an indication of this, they stated.
According to the report, it could be caused by the displacement of fish stocks and the sharks may be searching for food closer to the shore.
Blue shark facts
It’s a slender shark with a long, pointed snout; deep blue on top and white underneath.
Generally adults are around two metres long, but can reach four metres.
They specialise in small prey – feeding primarily on small fish, small squid and occasionally sea birds.
Blue sharks have been observed scavenging the carcasses of dead whales, according to the Encyclopedia Britannica.
The ‘tintonera’ as it is known in Spanish, is often accompanied by pilot fish.
Blue sharks are under threat because they can end up as bycatch of commercial fishing fleets, amongst other reasons.
It is not an ‘aggressive’ shark, according to eltiempo.com
According to the Shark Attack File, which has recorded all attacks that have occurred since 1847, the blue shark is not linked to any fatal incidents in Spanish waters.
Blue shark numbers have plummeted in the Mediterranean Sea in recent decades.
The Blue Marine Foundation notes that there are significant data gaps for sharks in the Med, including their migration patterns, breeding grounds, and the extent of the national fishing fleets’ bycatch.
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