If the water at Xlendi bay felt colder over the weekend than in recent weeks, it was not a figment of your imagination, according to a senior oceanographer.
Aldo Drago, from the University of Malta’s Department of Geosciences, told the Times of Malta that the strong northwesterly wind, the majjistral in the vernacular, which hit Malta over the weekend resulted in a natural phenomenon which cools the sea temperature down significantly.
“When a strong wind hits the coast, it pushes surface water away and forces fresh, cooler and nutrient rich water from the depths upwards,” Prof. Drago said.
Known as an “upwelling”, the phenomenon is not uncommon in the Mediterranean. It is the result of a wind that blows from southern France and Spain to the north-western Mediterranean, with sustained winds often exceeding 40 kilometres an hour.
Prof. Drago said the variation in sea temperature was significant, with waters around Gozo’s Xlendi bay and other northwestern bays recorded at 20°C on Saturday, while the sea at north-facing areas such as Marsascala, for instance, were at a much warmer 25°C.
When a strong wind hits the southern coast, it forces fresh and nutrient rich water up from the depths
“The longer the southern coastline, the more of an impact this wind has. This is why we see a much greater effect along the southern coast of Sicily, for instance, where a long stretch of cooler sea can be found following this wind,” he said.
Prof. Drago said the cooler water only lasted for a day or two because, once the wind died down, cold water stopped being pulled to the surface.
This phenomenon, however, had another effect. Prof. Drago said the wind would have also seen parts of the coast attract more marine wildlife, ideal for fishing.
“The upwelling doesn’t only bring up cooler water but also a lot of nutrients that attract marine life,” he said.
According to a 2001 study by Oxford University, as much as a fifth of the total global marine fish catches can be linked to the effects of upwelling.
Veteran Gozitan fisherman Charles Mercieca, 62, said he always looked out for a strong majjistral, describing the day after as a “fisherman’s delight”.
“Any fisherman worth his salt will tell you that those strong westerly winds are a headache when you have to move your boat to a safe location. But it is certainly worth it the following day,” he said.
Mr Mercieca said he had landed a reasonable haul when he went fishing early on Saturday morning with his son and fishing partner.
Once the strong winds on Friday night started to die down, the sea around Mġarr ix-Xini was teeming with fish.