Sunday, June 30, 2019

Sperm whales and bottlenose dolphins sightings with flat sea

The weather was the first beautiful part of the morning! The sea was incredibly calm and there was barely any wind, which made this day ideal for spotting cetaceans! So our morning started off great with a sperm whale. And another, and another, they kept popping up! We had the same unit of sperm whales as the other days. We saw the sperm whale named "Orca" who has a calf. 




As the sperm whale went to dive, we then headed to the bottlenose dolphins, the second resident species of the day. 




The dolphins were diving a lot so at some point we headed back to the sperm whales who had resurfaced by this time. We observed the sperm whales resurface one after the other. Time flies when you're having fun so we headed back to ponta delgada to end the tour, with smiles on our faces :)



In the afternoon we enjoyed again the same group of sperm whales. Some of them were foraging, so we managed to see some tails too. And again, some of the well known whales appeared: Orca and Diamond were around. In the afternoon we were not lucky with the dolphins, but the sun keep on shining reminding us that the summer is finally here!



Saturday, June 29, 2019

Beautiful pilot whales in Pico, as well as sperm whales, Risso's dolphins and striped dolphins!

Today the good weather and our beautiful Ocean fulfilled our heart with happiness! Risso’s dolphins where our today’s first sighting, just a quick welcome into the Ocean. 



Unfortunately, we couldn’t stay for long as we also wanted to be with the female group of sperm whales that were getting further and harder for our lookout to ‘control’. This group was beautiful, with the two different juveniles staying near two of the adult females. 



The last individual we were with had no juvenile near it, so it got a little bit curious with our boat going underwater around us… All of these mammals are truly amazing. As we left our friends to go sight one other species our lookout was leading us up to, we still got to see two different species of beaked whales. Unfortunately, it is quite a challenge to see them in their quick surfacing’s but some of us got to see them! On the way again we sighted a small pod of striped dolphins always with their elusive behaviour, so we didn’t stayed with them for long. 






Gladly we crossed paths with a numerous pod of spotted dolphins we stayed for a while with. They are an amazing company as they get close to the boat to swim aside it. Today they were systematically jumping high and leaving us mind-blowing. To end our morning, we arrived at a pod of short-finned pilot whales. 




Big and calm these dolphins approached us and passed near us, but the big male stayed always at distance! What a beautiful morning out of the beautiful mountain island!

Spectacular day plenty of sperm whales, dolphins and a leatherback turtle!

Today early in the morning some of our boats navigated all the way to Ribeira Quente for a whale watching tour departing from this southeastern village. We enjoyed the extremely calm waters that the Atlantic Ocean was offering us and the soft lighting from an early summer day. On the way there we could even spot a leatherback turtle!


This species of turtle can arrive to measure 3 meters! During our morning whale watching trips we sighted 3 different species. Lots of sperm whales socializing, showing their tails while rolling and appearing all around our boats. We put the hydrophone in the water and indeed they were socializing as we most likely were hearing their coda's! Coda's are a type of sounds that the sperm whales produce to socialize amongst each other.





Bottlenose dolphins interacting with the sperm whales and giving us some of their always impressive jumps. 


And last but not least some common dolphins that even allowed us to swim with them.


A blue shark, a loggerhead turtle and Portuguese man-o-war completed the sensation of a vivid ecosystem.



In the afternoon we found again lots of sperm whales with similar behaviour. It seems they're socializing a lot these days, and we are for sure enjoying it to the most. We received the visit of students from the project MOVE Açores, a non-profit organization that believes in entrepreneurship as a way to fight inequality. They had a great time watching sperm whales and dolphins :)




Some common dolphins appeared at the end of the day feeding really close to our boats.
We hope summer is here to stay, beautiful lighting, pleasant temperature and rich marine wildlife.




Listening to the sound of our ocean

What it is a hydrophone and why do we use it?

Just as a microphone collects sound in the air, a hydrophone detects acoustic signals when submerged in the water. It transforms the incoming sound waves over a wide range of frequencies into electric signals. The hydrophone allows us to hear the sound as it is emitted underwater, coming from any direction (NOAA, 2019).


What sounds do whales and dolphins produce?

Sound is an important component of the survival of marine life, and it is used in many ways. Marine mammals, for example, have adapted in order to better use sound underwater. While toothed whales and dolphins use clicks to communicate, and echolocation for hunting and navigating, baleen whales generally produce a series of low frequency sounds (see figure 1 as an example) to communicate. Long distance communication is an important social component and very helpful because sound travels further in water than on land. Baleen whales, for example, can communicate up to around 180 km! (Balcazar et al., 2016). We can hear the sounds and clicks produced by cetaceans by using a hydrophone, but we cannot hear all the sounds!

Which underwater marine mammal sounds can humans hear?

As seen in figure 1, whales and dolphins emit sound at different frequencies, which means that not all hydrophones can detect and record all the species. Humans can only hear a certain range of frequencies: between 20 Hz and 20 000 Hz. This frequency range is what we called the “human auditory field”. Any sounds produced below 20 Hz, such as the ones emitted by the baleen whales, are low-frequency sounds and are called infrasounds; they are not audible to humans!

Figure 1: A graph comparing the frequencies of different emitted sounds and the hydrophone, which is a sound recorder and marine mammal sound frequencies cited from Woods Hole Oceanographic Institution (DOSITS, 2019).

On the other side, we have frequencies above 20 000 Hz, which are called ultrasounds. These sounds are high-frequency sounds that, in fact, humans cannot hear either. For example, in figure 1, the harbour porpoise clicks start at approximately 110 000 Hz (Woods Hole Oceanographic Institution (DOSITS); so humans cannot hear it.

What does Futurismo use hydrophones for?

In Futurismo we have several hydrophones that we usually use during our whale watching tours. They allow us to listen to frequencies that humans can hear (see the figure 1), so our guests onboard can hear what is happening underwater. The hydrophones used by Futurismo here in São Miguel and in Pico are mainly used to listen to the sperm whale echolocation clicks and the echolocation of dolphins. To hear these marine mammals, we can use a non-directional hydrophone, which “collects” sound from all directions (figure 2A). However, sometimes the hydrophones are also used to search for whales or dolphins. To do so, we need to use a directional hydrophone (figure 2B). It has a baffle, which is a plate-like structure that isolates the noise and vibration produced by the active element (Embleton, 2011) which could be an echolocating sperm whale. It is needed to have only one side of the hydrophone exposed to the ocean, so just one side that can collect sound. This way, the hydrophone can be turned into different directions, and sound will only be heard when an echolocating animal is found (see figure 2B). We can then go into the direction that the sound is coming from. We have been able to find sperm whales up to 10 km of distance from our boat by just using the hydrophone!

Figure 2A: Hydrophone records in all directions and can pick up all the sounds of the whales (Zetlab, 2019). 2B. Thebaffle” is attached to the hydrophone, and it blocks the sound behind it. In the figure it corresponds to the left side, i.e. the lighter part of the ocean. The hydrophone only picks up sounds in front of the baffle (brighter ocean, on the right side) (figure adapted from Zetlab, 2019).

What about the sounds (infrasound and ultrasound) that humans cannot hear?

We cannot hear the infrasounds and ultrasounds, however there are ways to measure them. Hydrophones can be set at different frequencies and record in this manner. Then, those records can be changed to a frequency that humans can hear. For example, the sound of a blue whale in this spectrogram had to be sped up by a factor of 10 to be audible by humans (DOSITS, 2017). The echolocation of a harbour porpoise, which produces one of the highest pitched ultrasounds by any animal on earth (Wahlberg et al., 2018), had also been slowed down to be audible to humans. For sperm whales, there is no need to alter their sounds, as they are naturally audible by humans.

Article by marine biologist, Fadia Al Abbar


Bibliography

DOSITS (2017). Discovery of sounds in the sea. The University of Rhode Island. Accessed online in February, 2019. https://dosits.org/galleries/audio-gallery/marine-mammals/baleen-whales/blue-whale/

Embleton, S.T. (2011). Methodology for the design of hydrophone acoustic baffles and supporting materials. Master thesis. University of Texas.

Kaur, K. (2012). What is a Hydrophone? Accessed online in February 2019.
https://www.azosensors.com/article.aspx?ArticleID=13

NOAA. (2019). What is a hydrophone? National Oceanic and Atmospheric Administration. Accessed online in February 2019. https://oceanservice.noaa.gov/facts/hydrophone.html

Wahlberg, M., Linnenschmidt, M., Madsen, P., Wisniewska, D., Miller, L., (2018). The Acoustic World of Harbor Porpoises. American Scientist. Accessed online in February 2019.https://www.americanscientist.org/article/the-acoustic-world-of-harbor-porpoises

Woods Hole Oceanographic Institution. Frequency Ranges of Marine Mammals. NOAA. Accessed online in February 2019. http://www.whoi.edu/oceanus/v2/viewArticle.do?id=174029&pid=174029

Zetlab. (2019). Underwater hydrophone. Accessed online on February 2019.https://zetlab.com/en/shop/sensors/bc-311-underwater-threaded-hydrophone/

Other interesting links:
http://cetus.ucsd.edu/voicesinthesea_org/
https://dosits.org/galleries/audio-gallery/marine-mammals/
http://www.cetaceanresearch.com/hydrophones/sq26-h1b/index.html 

Friday, June 28, 2019

Two sei whales and many sperm whales


Another amazing day out of Sao Miguel. In the morning we went to see sei whales, they were two individuals traveling west as it normally happens with this species. 




Then we went to have a look at a male sperm whale and it was our resident male Mr. Liable, it showed tail as usual, and one boat from the company could record its echolocation. 



 






In the afternoon we spotted a group of female sperm whales, some of them showed the tail to go for a feeding dive, we could recognize two individuals, one named Tonga who belongs to the blue unit and "Orca" who belongs to the red unit. It is curious that sometimes two units can be in the same place at the same time. 



Everything was going right but suddenly bottlenose dolphins appeared in the area making the sperm whales crazy, changing the way that they were swimming and the went really close to one boat, a really nice sighting. Then we went a bit further out to see the rest of the bottlenose dolphins.







Thursday, June 27, 2019

An incredible day plenty of species

In the morning we started our day with some bottlenose dolphins. Although we didn't stay very long, we managed to see them quite well. 



Afterwards, we headed to another area to see the sperm whales, and they were amazing today!!!!!! We were so lucky to see them socializing. They were turning where we could see their fluke raise out of the water from the side, and we saw them spy hopping as well. Spy hopping is when the sperm whale lifts its head, vertically, out of the water, having a look at what is happening at the surface. So, we managed to see their beautiful square heads above the surface. 


 



Then, some of the sperm whales became curious and swam towards one of the boats. Wow, we could see 4 sperm whales really close, and underwater! Then, for the grand finale, they decided to go for a deep dive and fluked (showed their tail) right next to the boat! What a lucky sight.
 





After seeing these beauties, we continued to see a third species, the risso's dolphins. These, too, had a really nice calm behaviour. The two risso's dolphins had calves which were really cute to see.  





In the afternoon we had a completely different trip! Some of our boats started off seeing the pilot whales first, which are always a nice surprise! We do not see these species every day. The pilot whales were diving a long time, but when they were at the surface, we could see them really well. Lots of the pilot whales had calves and newborns so it was a very special sight.





After enjoying the pilot whales, we headed to see the same unit of sperm whales that we saw in the morning. Miranda van der Linde identified this unit of sperm whales as the most sighted group of sperm whales around São Miguel, the red unit. Some of the flukers we recognised as Bear Paw and Left tip. Orca (name of a sperm whale) and Diamond were accompanied by calves. 


Additionally, on one of the boats, we listened to their clicks using the hydrophone, and it was quite clear. In the afternoon these sperm whales were foraging, as we heard their foraging clicks! On the catamaran we enjoyed a big pod of bottlenose dolphins, some were whistling while bow riding and some were leaping.


Related Posts Plugin for WordPress, Blogger...