A big shark was spotted yesterday, Wednesday 24 April, in the waters of Strait of Messina. The specimen grazed the boat of a group of fishermen a few meters from the coast of Pentimele, on the northern outskirts of Reggio Calabriaa few meters from the port entrance.
Because the Strait of Messina is an ideal habitat for sharks
Like every year, with the intensification of recreational activities, sightings or simple reports of sharks prowling the arm of the sea that separates the continent from Sicily are multiplying along the area of the Strait of Messina. And as usual there are those who question the veracity of the sightings, asserting that “sharks do not exist in the Mediterranean” or even more so “in the Strait of Messina“. In reality, since the dawn of time, the depths of the Strait of Messina have been inhabited by countless aquatic species of rare beauty that gather in these waters so rich in nutrients. Among these there are also various specimens of sharks, which we can consider as native species of the Strait, which represents the ideal habitat for searching for food, even for species accustomed to living at great depths.
Among these we find the blue shark or the flathead shark, better known by the scientific name of Hexanchus griseus Bonnaterre. In dialect also known by the term “piss cow”, as it is repeatedly identified by fishermen who live in the Strait of Messina every day, given its considerable size. The Capopiatto is the largest species of the family Hexanchidae. The main characteristic of flathead sharks is that they have a single dorsal fin.
Furthermore, their dimensions can vary between 140 and 480 cm. But some specimens can even exceed 5 meters in length, many of which have also been observed in the Strait area. Therefore it is not surprising if every now and then the feluccas that sail the waters of the Strait of Messina come across specimens of a rather large size. These types of sharks are used to living at great depths, and often, during the night hours, as often happens in the Strait of Messina, they can rise to the surface to prey on other fish or sometimes even swordfish and squid.
In the waters of the Strait of Messina, full of fish and rich in life due to the strong tidal currents which produce a truly unique water exchange in the world, the Flathead it is a very common species, usually harmless to humans. Furthermore, the abyssal habitat provided by the strait, with the seabed sinking to below 500 meters in the southern area of the Canal, is ideal for this species of animals which are often used to living at great depths.
The shark Flathead it is a fairly well-known species in much of the Mediterranean Sea and usually harmless to humans. But the Strait of Messina remains the only place in the Mediterranean where it is easier to observe it, even in the sections below the coast, at relatively shallow depths for this species. There are countless meetings and observations made by many expert divers (the Strait also boasts the best teams at national level) and underwater fishing enthusiasts between the Sicilian and Calabrian shores.
Like all other shark species, the Flathead would prefer to hunt on the Strait, during the entry of the current “Upright” which pushes enormous masses of water from the depths of the Ionian Sea to the northern mouth of the Strait. Due to its particular bathygraphy, the bottom of the Strait can be compared to an asymmetric mountain, with the opposite sides presenting decidedly different slopes. The crest of this sort of imposing underwater relief is represented by what the locals call “saddle”, i.e. the shallowest point located between the town of Ganzirri, along the Sicilian shore, and Punta Pezzo, on the opposite Calabrian shore .
Right from the “saddle”, located along the northern mouth of the sea arm, where the seabed reaches 64 metres, the two sides begin to slope towards the lower Tyrrhenian Sea and the Ionian Sea respectively. The one that dives towards the Tyrrhenian Sea (to the north) slopes much more gently, until it reaches 1000 meters of depth off the coast of the Gulf of Milazzo, while to find the bathymetric depth of 2,000 meters you have to go beyond the island of Stromboli. The southern side, however, slopes very abruptly towards the Ionian Sea, with a very steep slope, so much so that just 4-5 kilometers from the “saddle” the seabed sinks to below 400-500 metres.
In the stretch between the cities of Messina and Reggio, in the central part of the Strait, you descend below 500 metres, up to 1,200 meters just south of Punta Pellaro. Values below 2000 meters occur off the coast of Capo Taormina, where the seabed rapidly sinks into the abyss of the Ionian Sea, with a very steep slope a few kilometers from the coastline. This bathymetric profile, so harsh, favors the onset of frequent and violent tidal marine currents, among the strongest observed on our planet, which tend to ascend this step with particular energy, pushing very cold, heavy and deep waters to the surface. coming from the depths of the Ionian Sea.
In fact, within the Strait, there is a perennial difference in height, of approximately 27-28 cm, between the waters of the Ionian and those of the Tyrrhenian Sea, which decreases as one approaches the point of contact of the two basins, where it naturally disappears. When the waters of the Tyrrhenian Sea, north of Capo Peloro, are at high tide, the Ionian ones, south of Capo Ali, are at low tide. Along the Strait, thus, an intense situation is activated “tidal gradient” which tends to be filled gradually, on average every 6 hours, with the triggering of impetuous tidal currents which can reach truly remarkable speeds on certain occasions.
When high tide is in progress on the lower Tyrrhenian Sea, the Tyrrhenian waters flow towards the Ionian Sea, bridging this difference in level. The current that originates in a north-south direction (from Messina to Catania) will be called “Descending”. The flow of “Descending” reverses the situation, raising the surface of the Ionian basin which, once it reaches a certain level, tends to flow back into the Tyrrhenian Sea through the Ganzirri and Punta Pezzo lines.
In this way the process is reversed and a definite, contrary current develops “Upright”, which will go up the area of the Strait of Messina from south to north up to the northern mouth of Capo Peloro, causing the Ionian waters to overflow over the Tyrrhenian ones. As is known, both flows manifest themselves gradually, not simultaneously at every point, starting from the waters in front of Capo Peloro and subsequently extending to the other areas of the strait, up to its southernmost mouth, along the Ionian coast of Messina, in the stretch that goes up to Cape Taormina.
These currents are active throughout the water layer, from the bottom to the surface. In this context, on full moon days, when the maximum is reached “tidal gradient” between the Ionian and Tyrrhenian Seas, with a notable strengthening of the currents, the Capopiatti sharks seem to be lulled by the current “Upright” (from south to north) which from the dark depths of the Ionian Sea pushes them straight to the surface in the central part of the Strait of Messina, where they find the ideal habitat for hunting small fish and squid, always abundant in the waters of this very rich arm of the sea. As soon as the hunt is over they await the entry of the opposite current, the “Descending”very strong and violent on the surface, which takes them back to the depths of the Ionian.
Continue reading on MeteoWeb
