Sasha Whitmarsh and TFUI Founder Melissa met at a conference in Tasmania. They bonded over a mutual love of BRUVs -- Sasha worked with BRUVs and Melissa was fascinated by them.
Currently a PhD student at Flinders University in Australia, she took some time out of her busy schedule to answer some questions!
The Fins United Initiative: What is your project about?
Sasha Whitmarsh: We use BRUVS and similar video techniques for multiple projects within our lab. My PhD uses BRUVS to assess temporal changes in fish assemblages (e.g. between seasons and times of day), assess the potential influence of anthropogenic stressors and investigate ways to improve BRUVS itself as a method. We have another Honours project using BRUVS to assess the differences between pelagic and benthic fish assemblages, as well as a project using unbaited stereo video to measure the size of white sharks and other fishes at the Neptune Islands in South Australia.
TFUI: What are BRUVs?
SW: BRUVS itself is an acronym that stands for Baited Remote Underwater Video Stations, but there currently exists a few different names for similar methods. Basically BRUVS are just cameras mounted within some kind of frame with bait attached. They are usually deployed on the ocean floor (but can be pelagic) and left to record for specific amounts of time (commonly 60 min). They are usually tethered to surface floats to enable retrieval and are not tethered or linked to a boat (there’s no live stream to view). There are two main types of BRUVS, stereo and single set-ups, where stereo-BRUVS have two cameras spaced in such a way as to enable accurate length measurements to be taken of targeted organisms (or measure the distance away from the camera). Single BRUVS have just one camera facing out to the bait and it is more difficult to record length measurements, but they are smaller and cheaper to build and thus logistically easier to use.
TFUI: What does BRUV data help show?
SW: BRUVS can be used to record multiple useful metrics including relative species abundance and diversity, habitat type, behavioural interactions of individuals and species, time of arrival and feeding data, and length/biomass estimates if using stereo-BRUVS.
TFUI: What data do you hope to get from them?
SW: I’m hoping with the data I gather from my BRUVS I am able to improve our understanding of temperate fish assemblages, especially in understudied areas such as at night and in under-sampled habitats such as seagrass and soft sediment areas. I’m hopeful to be able to untangle potential influences on fish assemblages of multiple anthropogenic stressors and investigate ways to improve BRUVS as a method and the data which can be extracted from it.
TFUI: How have you found working with BRUVS to be like? What are the challenges?
SW: There are a lot of things I like about working with BRUVS. It can be quite a gear intensive fieldwork operation, with the need for the frames, cameras, batteries, SD cards, bait arms and bait bags, actual bait, ropes, floats, safety gear etc. but once it’s been done a few times it is easy to get the hang of it. Like any fieldwork, when the weather is good, it is much easier to deploy and retrieve the BRUVS and I enjoy the fieldwork immensely. Right up until about 2 am I even enjoyed the night-time BRUVving, the magic of seeing the stars and if we were lucky the bioluminescent organisms in the water along with the quiet of the night was something special.
The biggest time drain using BRUVS is the video analysis back in the lab. It can take anywhere from about 40 min to 2 hrs to view a single 60 min replicate (you can watch them in 2x speed) and I deployed more than 500 replicates for my PhD! I found watching the videos to be both exciting and terribly monotonous. The thrill of seeing a new species or interesting behaviour vs. watching fish swim around for 8+ hr a day. One of the ways I found to stay motivated was by having a wish list of species to observe and hoping that maybe the next video would have one on it, but alas this list got increasingly more outlandish over time and currently I’m still waiting to see that mola mola or pod of 20 orcas (not to mention the oarfish).
TFUI: What’s been the most interesting BRUV video data you’ve had?
SW: I’ve seen many interesting things on the videos. Since many of my colleagues come from a shark lab, they are always excited by the big chondrichthyans such as the white sharks, bronze whalers and hammerheads. I’m always excited by seeing cephalopods, squid being the most common I observed, but there were also a few giant cuttlefish and an octopus or two. One of my favourite things (and there weren’t many) about watching the night videos was all the adorable bobtail squid that came out and checked on my BRUVS. Generally, I was often amazed by the number of fish around a BRUVS or by the diversity of species I observed and anytime the visibility was good, I was happy to be watching that replicate. The most surprising video would have been when I got a great shot of a weedy seadragon that came right up close to the camera.
If anyone wants to know more about the ways in which BRUVs are used, Sasha and her team have recently published a literature review on the topic:
Whitmarsh SK, Fairweather PG, Huveneers C (2017), What is Big BRUVver up to? Methods and uses of baited underwater video, Reviews in fish biology and fisheries, 27:53–73
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TFUI Founder Melissa C. Marquez is author of all animal bios and "Behind the Fins" segments.
SEE MELISSA'S TEDx TALK HERE:
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