Acoustic Telemetry – “Researchers use acoustic telemetry to collect information about fish movements (e.g., migration patterns, habitat use, survival). An acoustic telemetry system consists of two main components: transmitters and receivers. Transmitters are electronic tags that broadcast a series of “pings” (sound pulses) into the surrounding water. Tags are either surgically implanted or attached externally to a fish of interest so that once released into the wild, a tagged fish can be “heard” by any receiver within range. The range can vary from a few meters to more than a kilometer. The signal typically transmits once every minute or two. Receivers are small, data-logging computers anchored near the bottom of a lake or stream or the ocean that “listen” for tagged fish. When a signal is identified, the tag’s unique ID code is saved with the date and time. The data from any single receiver provide a record of each visit to that location by a tagged fish. Researchers often deploy many receivers over large regions to understand the movement patterns of tagged fish.”
Much of my research on sharks has centered around understanding where they occur in time and space. This info is vital to determine how they view and interact with the world around them. My goto method has traditionally been acoustic telemetry, that solves many of the problems associated with tracking animals that occur underwater (radio transmissions that are typically used for terrestrial tracking fade quickly when passing through water).
For the purpose of tracking sharks, we use two approaches to acoustic telemetry, the first, and definitely the most enjoyable, is the active tracking of sharks, in which your received is located on your vessel and you, in essence, follow around behind the subject for as many hours as you can. Over the past decade, our team at Oceans Research have notched up some of the longest continuous track of sharks ever completed, including three efforts of over 100 hours! In fact, it was during one of these marathon tracking sessions that I discovery that the white sharks at Mossel Bay can hunt and attack seals in all light conditions including night – as featured on National Geographic’s – Sharkville documentary.
The second method uses an array of receivers that a located onto the seabed. These permanent receivers listen out for the transmitters been carried by sharks, then record and archive there presence. Over a period of a few years you are able to determine when sharks occur in certain areas, and how long they stay. Also, as this technology grows and more scientists utilise the acoustic receivers, we know if our sharks go on big travels and are picked up on other receiver arrays run by our colleagues from around the world.
To read more about my research using acoustic telemetry check out my scientific writing: Scientific publications