FEATURE: ORCAS IN THE STRAIT OF GIBRALTAR
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ORCAS IN THE STRAIT OF GIBRALTAR One of my favourite stories of the seas is the one on the Orcas that visit the Strait of Gibraltar. I have encountered Orcas when sailing in the middle of the Atlantic Ocean, in the Galapagos islands or in Norway … but the most impressive interaction of these extraordinary marine mammals in the wild with humans, happens between the columns of Hercules. During 11 years of my life I have been collaborating, on and off, with firmm® (Foundation for Information and Research on Marine Mammals), founded in 1998 by Katharina Heyer in the little fishermen village of Tarifa. This was the beginning of research on marine mammals in the Strait of Gibraltar, as not data was available on the subject at the time. In those days we were a little group of Oceans Lovers passionate and curious about the story behind the presence of dolphins and whales in the Strait and wanted to know more. Nowadays, firmm became a whale-watch operator and before every whale watch trip, volunteers give the passengers talks about the marine mammals and environmental concerns in several languages. Between 2001 and 2011, we organised educational campaigns with the collaboration of government and corporate funds, which allowed us to reach out to over 20.000 scholars in the region. The little village of Tarifa is the most Southern point of continental Europe and is situated in
the heart of the Strait of Gibraltar, just 14 km away from the African continent. Therefore, the closest point to Africa is the little military island of Tarifa and not “Europa point” in Gibraltar. The little village of Tarifa has a worldwide reputation to be one of the best windsurf destinations, more than for its marine mammals… but they are there! The Strait of Gibraltar is known for drugs and immigrants’ transit, but is also one of the areas with the most maritime traffic in the world with nearly 350 ships transiting in- or -out it every day. The Strait of Gibraltar also emblematic because it is where the Mediterranean Sea and the Atlantic Ocean meet. Every 6 hours, through the tides, the Atlantic pushes into the Mediterranean who does not really have anywhere to go apart from the Suez Canal. Because the evaporation of the water during the summer months, the Mediterranean is warmer and also has a higher salinity then the Atlantic Ocean. For this reason, the Atlantic goes down to the bottom of the seabed and revolves the dead sediments of the Mediterranean bringing them up to the surface … which is called “upwellings”. Through photosynthesis, plankton will bloom again and start-up the food chain; from phytoplankton, zooplankton, krill, small fish, to all the way up ... marine mammals. In the Strait of Gibraltar, we can encounter 4
species of resident marine mammals, being the common dolphins, the striped dolphins, the bottlenose dolphins and about 600 pilot whales. Because of the small distance between the two continents it is also a good spot to observe larger whales, like sperm whales or fin whales during their migration in- and out- of the Mediterranean. The Orcinus Orca or “Killer Whale” got this nickname because they are known to eat other marine mammals such as seals, dolphins, or young whales. No humans have ever been killed by Orcas in freedom, and the only known cases of humans being killed by killer whales were by animals in captivity. I invite you to read an article I wrote called “marine mammals in captivity” to be found on my LinkedIn, Facebook, or look it up in “The Islander” magazines’ digital format (May 2020). Before entering in detail about the Orcas and their interaction with humans we first need to understand the fishing of the largest tuna in the world, which is as main reason behind the reason of the Orcas visiting the Strait of Gibraltar. The Atlantic Blue-fin Tuna (Thunnus thynnus), or in Spanish “Atun Rojo”, is the largest tuna in the world. This fish can weight up to 680 kg and generally swims between 500 and 1000 meters deep. This apex predator lives generally till the age of 15 to 30 years. This pelagic specie does not use their gills for