Weekly Update July #3
Weekly Update July #2
Weekly Update June #5
Weekly report: June #3
Weekly report: June #1
In the past week we found dolphins in all of the dolphin watching tours. We took less than 1h to find the first dolphin group in 50% tours and in all of them we found at least a second group.
The Lisbon&Dolphins afternoon tours, had 50% chance rate of seeing dolphins.
We sighted just one dolphin species last week, the common dolphin, normally groups with adults, juveniles and babies.
On average, we had 8 guests per dolphin watching tour and no seasickness cases. Sea state was on average sea state 1 (in the picture).
This week we expect very calm mornings perfect for dolphin watching and windy afternoons that will not be suitable. From Wednesday 7th to Friday 9th we expect degradation of sea conditions and maybe some rain. We will assess if is doable to rely only on the river to find the dolphins.
Update: From Wednesday 7th to Friday 9th there will be no tours, due poor sea conditions and lack of dolphins in the river. We expect the return of dolphins to the river on the weekend (10th-11th).
Monthly Reports: May
We found dolphins in 95% of the dolphin watching tours, an underperformance to the previous months (100%). Only one tour failed to find dolphins despite covering more than 90km. It was a case of forecast underestimation, the sea state of 5 forced us to severely restrict the search area to coastal areas and none of the dolphin watching boats found dolphins that day.
The Lisbon&Dolphins afternoon tours, had 81% chance rate of seeing dolphins.
We sighted 3 different cetacean species. The common dolphin was the most sighted dolphin species, followed by the harbour porpoise (which isn’t a dolphin) and finally the very large bottlenose dolphin.
On average we had 7 guests per dolphin watching tour and no seasickness cases. Sea state was on average sea state 2.
We started testing some upgrades, some proved to enhance the experience and to provide better fan service. In June we will start the implement fase for some of them.
We also made the first recordings for acoustics studies. Check out the ‘dolphinish’ language!
Orca found dead
A female Orca was found dead in Algarve, south of Portugal. It was with great apprehension that Francisco saw the first photos, showing a missing right flipper. Corsica 018, a known female orca from the Iberian population was the only orca known to have a missing (right) flipper. After being towed to shore, on her arrival to the docs, the distinct scar on the base of her dorsal fin put all doubts to a rest, she was Corsica.
We sighted Corsica in our first dolphin watching tour in Lisbon, back in 2017. She and her daughter, Matteo, travelled with Morales’ pod and we found them 30 min from Lisbon, just off Caparica coast.
Corsica born around the year 2000-2002, making her 20-22 years old, young for an orca, as her grandmother Toni, is still alive and around 50 years old.
She left 2 offspring, Matteo with 5 years and Isa, turning now 1 year.
She does not belong to the ‘famous’ group GLADIS, she was not observed involved in the events of interactions, with any type of boat.
Iberian Orcas collaborated with Neanderthals
Orcas and Neanderthals collaborated in the Strait of Gibraltar to hunt the Atlantic bluefin tuna, according to research.
According to the fossil records found in caves used by the Neanderthals in Gibraltar, it was found that they fed on tunas, despite not having instruments or boats to capture them.
Iberian orcas are a genetically distinct community from the northern European orcas and bluefin tuna play a major role in their diet. As bluefin tuna pass through the Strait of Gibraltar for spawning during Summer, Iberian orcas concentrate efforts in this area to hunt this fish. The Iberian orcas community is composed by family groups with different hunting techniques. Some steal from the fishermen lines, some chance the tuna, tiering them or trapping them on the beach.
Is the last hunting technique that scientists believe that could had been refined with the help of Neanderthals. The orcas would corner the tuna among several members and have them beached on the beach and would receive in exchange the remains of their consumption by Neanderthals.
The orcas benefited from this as they would consume much more energy if they had to tier the fish on their own.
This is not unprecedented, as orcas and whalers collaborated in recorded history. This happened in Eden, in south-eastern Australia between 1840 and 1930. Where whale-eating orcas would shepherd whales into Twofold Bay, there the whalers could kill the whale more efficiently than the orcas and the boats were too small to withstand open ocean and could only operate inside the bay. So that is how both species were benefited.
Who are the Lisbon Dolphins?
Dolphins had been frequently sighted in the Tagus river for 50 days now. It has been incredible the day by day frequency that common dolphins are seen so close to the city centre.
During this time it is clear that all these sightings were just a visit, as the groups quickly return to the Sea after a meal in the river. These are in agreement with the data from past years, only with the higher frequency.
There are many reasons that could explain this phenomenon and most likely it will not be just one. We keep a firm position on the food source hypothesis as the heaviest factor, published on the last article. However some pertinent hypothesis had been put on publications from others, namely:
- The improvement of water quality, which could very well explain an increase over the past decade, but unlikely to explain a large increase since the past year
- The dolphins in the river are just a reflection of an increase in the numbers of the overall population of dolphins in the Portuguese coast
The last one is puzzling and on our last tour we managed to put some light on this subject. Through photo-ID we managed to positively match at least half of the 21 identifiable individuals from the last sighting. These individuals were all sighted together in July 2019, just 1 hour worth of swim from the mouth of the river. We can conclude that these dolphins are locals that had been around for few time.
It can not be implied that it is always the same group visiting the Tagus river, but data points towards that at least that a ‘core group’ of individuals is on the large majority of the sightings in the Tagus river in 2020. It is to be noticed that all of these ‘core group’ individuals were sighted together in 2019.