Why do scientists eavesdrop on whales and dolphins? What can recordings of whale and dolphin sounds tell us? How do you even record the sound that these creatures make? And what’s it like to go to Antarctica?
Join us on Saturday, May 25 at Te Papa for a FREE talk by NIWA scientists Dr Giacomo Giorli and Olivia Price to hear the answers!
As part of the build-up to Eavesdropping Underwater, we interviewed Dr Giacomo Giorli about his role as a marine mammal acoustician. Dr Giorli’s work has taken him around the world, from studying dolphins in the Ligurian Sea to investigating predator-prey relationships in the waters of Hawaii. He has continued this work at NIWA, including involvement in a pioneering underwater sound project that recently gained national headlines.
What first drew you to oceanography?
Curiosity. I grew up close to the sea, and I was just curious about it.
What makes you most excited in your current job at NIWA?
The possibility to study many species in the Southern Ocean that we know almost nothing about, and the incredible amount of technology that we have at NIWA to conduct research.
You recently discovered clicks from unknown beaked whales in the Cook Strait. What would you like to do next to follow up this research?
That work was the result of a study conducted by all the researchers that authored the paper, and not just my “discovery”. It was a collaborative work. One important thing to note is that we did not discover unknown or new species of beaked whales (as many people always think). We recorded echolocation signals from beaked whales in Cook Strait that were not previously described in literature. We know the signals are from beaked whales, but we do not know what species of beaked whales are producing them. I guess a natural follow up to this research would be to identify the species that are using these sounds.
You’ve also studied the foraging behaviours of sperm whales and other toothed whales in Hawaii. What was it like completing this research, and what were the results?
That research is far from completed. In reality what I was studying in Hawaii was just the tip of the iceberg of deep sea predator-prey studies involving deep diving toothed whales. The toothed whale species studied in that research are species that dive very deep to search for food. They can dive deeper than 1 km. Because of this, it is essentially impossible to observe their behaviour directly. One can go in the African savanna and observe predator behaviour directly. Think about cheetahs hunting. We all are familiar with videos of cheetahs chasing impalas. What I want to point out is that when you have to deal with working in the deep ocean in general, making observations is incredibly challenging. We face the problem of observing how deep sea prey drives the distribution and behaviour of their predators.
In Hawaii, I tested new acoustic technology that would allow researchers to understand how prey availability and type could influence the behaviour of the deep diving predators (toothed whales). Data indicated that sperm whales, for example, foraged more where they had chances of finding larger prey, rather than where they had chances to find more prey. It seems counter-intuitive that they would rather go in a place where there is less potential prey. It suggests that these predators are somehow picky in choosing their prey.
As well as whales, your work also involves recording sounds from creatures as tiny as marine algae. What are the similarities and differences in working at these different scales?
The research I did on algae with my colleagues in the U.S. was a laboratory experiment. We did not go to sea. Algae do not have a sound generator like vocal cords. The sound is produced by oxygen bubbles that are expelled from the algal tissue during photosynthesis. However, the signal processing techniques we used to analyse the acoustic data are pretty much the same used for cetacean bio-acoustics research.
If money wasn’t a problem, what would be your ideal research project?
I guess the ideal research project in Marine Sciences is the one that ends well without failures of instrumentations and other things that can go wrong at sea.
For more insights into Dr Giorli’s work, join us at Eavesdropping Underwater: the Sounds of Whales and Dolphins on Saturday, May 25 at Te Papa!