It was a Tuesday morning when I received that email. I must have misunderstood… It just can’t be right.


Since I started to work in underwater acoustics, I have had the privilege to work with many smart and friendly people. People that influenced not only my career but also my personal life. Callum is one of them. I have met him at the Canadian Healthy Oceans Network conference in Ottawa back in 2017. He was presenting some of the work he was doing for his M.Sc. at Memorial University in Newfoundland. His project was quite interesting. He put together a high definition cinema-grade camera system towed on the seabed to map benthic communities off New Brunswick. He was specifically interested in how the distribution of sea potatoes (Boltenia ovifera) was related to the physical properties of the ocean. If sea potatoes are not your thing, believe me, talk to Callum and he will make them be your new favorite animal! His enthusiasm and passion were contagious. We connected right away. When I explained to him the camera system I was trying to put together I could see sparkles in his eyes. Since that day we started to work together. He brought to me his technical expertise and a wealth of experience on camera systems, and I helped him out with some programming he needed to process his images. He is the one who pointed me towards the 110-degrees camera lens I am using now. He is also the one who introduced me to the Trident ROV. In May 2018, we met again in Montreal for the World Conference on Marine Biodiversity. We even shared a room to keep the travel costs down. He was about to finish his M.Sc., just found a dream job in Newfoundland and was moving soon with his girlfriend.

When I received the email that Tuesday morning with the subject line “Callum Mireault”, I immediately thought that Callum wanted to chat about a script I had just sent him. Then, I read more carefully and realized that the message was not from Callum but from Paul Snelgrove, a professor at Memorial University working with him. I kept reading and re-reading the email trying to find the part that I misunderstood. But no, unfortunately, I understood correctly... Paul was announcing that Callum had a heart attack and passed away. He was not even 30.

Still to this day, I have a very hard time wrapping my head around the loss of Callum. This project would not be where it is now without him. He would certainly have been excited to be part of this expedition.

Building an autonomous video camera system that can record continuously for several days has been challenging. But things are coming together. We finally tested our first prototype in the field. Tristan took the system out to Madrona Point, close to Nanaimo. He and Courtney, his diving partner, dove and placed the camera prototype and an acoustic recorder at a site covered in Yelloweye and Quillback rockfish.

The test was very successful ! The camera worked well and we gathered data that will allow us to improve the system. Very encouraging! Also very excited to report that we recorded our first rockfish sounds!

Photos by Tristan Blaine.

For our expedition, one of the great tools that we plan to use is the Trident Remotely Operated Vehicule (ROV) from OpenROV. This is basically the underwater version of a drone. It "flies" through the water and thanks to its integrated camera, let you see and explore the ocean just like if you were diving. Unlike many ROVs, it is small, very portable and can be controlled from shore or from any type of boats (motor boats, kayaks, etc.). This amazing little instrument will be key for many aspects of our expedition.

Searching for good deployment sites. Once we have selected the general location of our study sites, we need to find the perfect spot to deploy our hydrophone and camera array. It needs to be relatively flat for the structure to be stable and close to fish aggregations, so we can capture their sounds. The Trident will be used before the deployment to identify good locations for the array.

Retrieving the hydrophone array. Deploying the hydrophone array on the ocean floor is easy. We just lower it down from the boat with a line. Once the array is on the bottom, we let go one end of the line and pull on the other end to get it back. To retrieve the array, this is more tricky. We need to find a way to attach the line back to the array. We can't leave a surface float on the array like crab or lobster traps because it would make too much noise that would contaminate our acoustic recordings. So, instead we will use the Trident to hook the line back to the array. Just like the video below. Then, we can pull the array back at the surface from the boat using that line. This retrieval technique is efficient, requires only 2 persons and will allow us to deploy in many places around the BC coast.

Cataloging fish sounds. Many fishes like to hide and hang out in rocks and boulders. Unfortunately, due to its size and shape, our hydrophone and camera array can only be deployed in areas where the bottom is relatively flat. So, we will design a small array of 2 or 3 hydrophones that we will attach to the Trident. These hydrophones combined with the camera from the Trident will allow us to catalog fish sounds in much more complex habitats than with the fixed array. This idea is actually not new. Rodney and Francis have already tried to add hydrophones to ROVs almost 10 years ago (see their paper here). But what they found at the time is that regular ROVs are very noisy and make the recording of fish sounds very challenging. With its much smaller and streamlined design, we are very confident that the Trident won't have that problem.

I am so excited to start playing with this really neat ROV!

​To catalog fish sounds in their environment, we need hydrophones to record sounds and cameras to visually identify the species making them. But what if a fish is making sounds outside the field of view of the camera ? Well, this could be a problem... When we see a fish on the camera, we need to make sure that it is the one making the sounds. This is where the passive acoustic localization comes in.

Imagine yourself in a busy street of a city. Now close you eyes and listen.... The jack hammer across the street from the construction workers, the siren of the ambulance passing by, the bird chirping away above your head, a baby crying in a stroller behind you. Even though you can't see them, you know precisely where all these sounds come from. And all of this is because your ears are few centimeters apart and don't receive the sounds exactly at the same time. Only few microseconds...but this tiny difference is enough for your brain to find out where the sound comes from. For our fish sounds we can use the same principle, except that we use hydrophones instead of our ears and that we are not limited to 2! The more hydrophones you use, the more accurate the localization.

Earlier this year, we published a proof-of-concept paper just showing that. We used data that Rodney had collected several years ago in Cape Cod with 6 hydrophones and a 2 cameras, and were able to localize sounds in 3D and associate them to a fish called the tautog. For our expedition in British Columbia, we will use the same approach. However we can't use the same instruments. The system used in Cape Cod was cabled to a dock and could only record for 2 or 3 hours. For our expedition we need to record for several days at a time and in places that are too far from shore to use cabled instruments. This looks like a detail, but it is actually a fairly big challenge that has kept me busy for some time. Especially for the video camera. There are no video camera systems on the market that can record autonomously for several days (at least at a reasonable price). So, I have been working away on designing a low-cost camera unit based on raspberry Pi computers. First field test to come soon...

Rodney has been studying fish sounds for decades! It is truly a privilege to be able to collaborate with him on this project. Listen to his short introduction to the topic. You can also check out his website.

​This expedition could not happen without the support from our sponsors.

From the engineering of the instruments, selection of the study sites, to the analysis and interpretation of the data, this expedition touches on many research fields. Each member of the team brings a unique set of skills that is essential for putting all the pieces of the puzzle together.

Xavier Mouy, MSc
Xavier is a PhD student in acoustics at the University of Victoria, Canada, and a project scientist in the environmental consulting company JASCO Applied Sciences. He is leading this expedition as part of his PhD thesis supervised by Dr. Francis Juanes and Dr. Stan Dosso. Xavier comes with 10 years of experience in the industry developing tools for automatically detecting, classifying and localizing marine mammals sounds. He is keen to help making passive acoustics a viable tool for monitoring fish in British Columbia.

Francis Juanes, PhD
Francis is the Liber Ero Chair for Fisheries Research and a Professor at the University of Victoria. He is a specialist on the behaviour, ecology and evolution of fishes and marine invertebrates. His research also includes the use of marine soundscapes as a tool for conservation. He is at the head of many research projects in British Columbia dealing with the impact of noise on endangered southern resident killer whales and their prey. His wealth of knowledge and experience on fish ecology and biology are key for all the phases of this project.

Stan Dosso, PhD
Stan is a Professor in geophysics and ocean acoustics at the University of Victoria and the director of the School of Earth and Oceans Sciences. He is a worldwide expert in Bayesian inverse methods and has developed state-of-the-art algorithms for geoacoustic inversion. He has worked on many different topics ranging from estimating geoacoustic properties of the ocean bottom in the high Arctic, analysing earthquakes off British Columbia, to tracking bowhead whales and walruses using passive acoustics. Stan’s expertise is fundamental for the analysis of the acoustic data collected by our hydrophones.

Rodney Rountree, PhD
Rodney is an independent fish ecologist based in Cape Cod, Massachusetts and visiting scientist in the biology department at the University of Victoria. He is an expert on fish habitat use, behavior and trophic ecology, but you might also know him as the Fish Listener. He is one of the pioneers in the field of fish bioacoustics and has over 20 years experience in the identification and analysis of fish sounds around the world, from piranhas in the Amazon River to haddock in the Gulf of Maine. Rodney brings his expertise with fish sounds and the application of passive acoustics to fisheries science to the team.

Tristan Blaine, BSc
Tristan is a biologist, commercial diver and field lead with the Central Coast Indigenous Resource Alliance (CCIRA). He has extensive field experience and spends most of his time underwater surveying rockfish, herring and crab habitat. He knows more than anyone else where to find the different species of fish in British Columbia. His knowledge of the coastal waters of British Columbia and his field experience are essential for selecting our study sites and facilitating the logistics of the expedition.

​“Prrrrr… thump… thump… brrrrr…”, these are the sounds you can hear in the coastal waters of British Columbia. Sounds the fish can make to scare away predators or attract mates. Yes, you read correctly, fish make sounds! And it has been known for a very long time. Aristotle was already describing these intriguing sounds in the 4th Century BC. Despite this, we still don’t know very much about the different types of sounds fish make and what they use them for. Currently, we know that about 800 species of fishes worldwide produce sounds. Among the approximately 400 known marine fish species frequenting the waters of British Columbia, only 22 have been reported to produce sounds so far. It is believed that many more of these species produce sounds, but their acoustic repertoires have not been identified yet and this is exactly what this project is about: Exploring the coastal waters of British Columbia to record and identify the sounds produced by the various fish species frequenting these waters.

Why do we care? The fish sound catalog we are building will allow us to monitor fishes over long time periods and large geographic areas in a completely non-intrusive manner, just by listening to the ocean. This will constitute an important tool for marine conservation and fisheries management.

How will we proceed? Fish don’t behave the same in a fish tank as in the wild. This is why we will record fish sounds directly in their natural environment. To identify fish sounds to specific species and behavior, we need to have our eyes and ears underwater. We need to know exactly where the sounds come from to pin-point which fish is producing them. Acoustic recorders equipped with hydrophones can be used as our ears and underwater video cameras as ours eye. Using several hydrophones, we can precisely localize the origin of the sounds in three dimensions.

Due to the complexity and the diversity of fish habitats, two different instrument systems will be used. For areas with a relatively flat seafloor, we will use a compact autonomous array composed of 6 hydrophones and 2 underwater cameras. This fixed system will be deployed on the seafloor for up to 1 week at each location. For steep seafloor slopes and complex habitats such as boulders, we will use a Trident ROV equipped with 2 hydrophones. This mobile platform will be employed for short-term missions (few hours).

There are several technical challenges associated with this project. For the fixed observing platform, one of the biggest challenges is that there are no off-the-shelf autonomous camera systems that can record for several days in a row. Consequently, we will design our own using a low-cost Raspberry Pi single board computer. For the mobile platform, the challenges reside in integrating the hydrophones to the Trident ROV.

Currently, we are building a prototype of underwater camera (pressure housing and electronics) and will be testing it in the next few days.