One of our bigger pieces of equipment used in the MCA project is the Baited Remote Underwater Camera (BRUV) or "Baited Cam". The Baited Cam is composed of a metal frame used to house and protect the camera, lasers, lights and battery while stationed on the seafloor. This piece of equipment typically gets deployed at the last station of the day, and is left over night. It is attached to an anchor and an AIS identification beacon so that we are always able to locate its exact location. While stationed on the seafloor the camera will continuously record 10 minute videos over a 10 hour time period. We attach bait, typically squid, to the arm of the frame in an attempt to attract species that may be present in the area. In the video below, an abundance of cod is captured on camera at our last sampling station! This is great to see as the main objective of this Marine Conservation Area, Hawke Channel, is to conserve a vital habitat for Atlantic cod!

July 17th, 2023

Another research objective of the MCA project is the collection and analysis of fisheries acoustics data. We collect this data through the use of both the EK80 scientific echo sounders and a Wide Band Autonomous Transceiver (WBAT). The EK80 system is connected to four transducers attached to the side of the boat via a pivoting “arm” that reaches down into the water. Each transducer emits a pulse of sound through the water column that echoes off anything it encounters, returning the signal back to the transducers. This information is displayed in real-time on monitors in our dry lab and allows us to detect marine life present throughout the water column. As mentioned, we use four transducers; each emits a different frequency of acoustic signals. The difference shown between each of the frequencies on our monitor gives us some indication of what marine life is being detected. Lower frequencies are typically used to detect fish species present in the water, especially species with swim bladders as the density difference between the water and the air within the swim bladder resonates strongly with a 38khz frequency. Higher frequencies do not reach as deep depths as lower frequencies do, and are not as great at detecting fish, these higher frequencies are often used to detect smaller species such as zooplankton.

The WBAT has two higher level frequencies and, we use this equipment to get a closer look at what marine life may be present on the ocean floor. We accomplish this by the way we use the equipment, the EK80 echo sounders are attached to the vessel and emit signals from just below the bottom of the vessel which can weaken the signal in deep waters. But the WBAT is deployed on a cable to approximately 30 meters above the ocean floor allowing even the high frequency signals to be strong enough to detect species at depth.

We compare our acoustic data to the underwater footage captured by our baited camera and drop camera. Using this footage we can physically see what the acoustic data is detecting, allowing us to narrow down which species are being displayed by the four different frequencies. You can see from the photo below that the frequencies are shown from lowest (left) to highest (right), the black circle indicates a signal most likely detecting fish in the water column, while the area within the brown circle potentially indicates zooplankton. You can also see from this image that the signal for the highest frequency is not as strong as the others as it reaches depths of almost 400 meters.

July 21st, 2023