Nicola King and Monty Priede, Oceanlab, University of Aberdeen, work with landers that carry cameras down to the deep seafloor to photograph deep-sea scavenging fish in their natural environment. Studying animals in their natural environment is difficult enough but when the animal you are interested in lives deep at the bottom of the sea under really high pressure AND with no light, it makes it particularly challenging! So read further to discover just how Oceanlab do it…
By Nicola King and Professor Monty Priede, Oceanlab, University of Aberdeen
Oceanlab uses things called landers; landers are metal frames onto which scientific instruments are attached, such as cameras. Weight (ballast) causes the lander to sink to the seafloor where it carries out a series of pre-programmed tasks; in this case it takes pictures once every 90 seconds for periods up to 7 hours.
The camera looks down onto the ballast, a ruler for scale and some bait (a single mackerel). Mackerel is very smelly, and attracts scavenging fish to within the field of view of the camera. Once the camera has finished taking pictures a sound signal is sent from the ship, causing the lander to drop it’s ballast, it is then returned to the surface by a series of floats attached to a mooring line above the lander frame. The lander, camera and images can then be recovered.
Once the images have been downloaded from the camera they can be analysed to provide us with information on the types of animals that visit the bait, their size and numbers. Once Nicola gets back to lab she can go through all the pictures one by one identifying the fish, measuring and counting them. Nicola never knows what she’s going to come across in the next picture, and often there are big surprises like huge sharks and really weird fish!
Photografed fish at the bait
Since the end of the cruise Nicola has analysed over 4000 photos! 21 different types of fish came to the bait and were photographed by the camera, including 4 species of sharks and rays, a species of chimaera (rabbitfish), and 16 species of deep-sea bony fish!
The most common fish at the bait below 2500 m (125 football pitches!) were deep-sea rattails – you can just imagine how ugly they are from their name! We also found that the number of different types of fish that come to the bait get fewer as you go deeper, probably because there is less food available.
Enables to understand and protect the oceans
The deep-sea environment makes up a huge part of our oceans, so it is vital that we understand and protect it. Taking pictures of deep-sea life all over the world in our seas and oceans helps us to understand the depths of our most valuable living resource, giving us an extremely important portfolio of which animals live where and why.