The Ocean Tracking Network (OTN), headquartered at Dalhousie University in Nova Scotia, tracks many commercially and culturally important, and endangered aquatic species globally, including sea turtles, squid, salmon, sturgeon, and several species of sharks.
Over 400 international researchers from 19 countries are currently participating in the global network that aims to generate the scientific knowledge that will best inform global ocean-resource management for sustainable use of the oceans.
How Acoustic Telemetry Works
Telemetry is derived from the Greek words tele (remote) and metron (measure).
Telemetry is the science of measuring (or tracking) something from afar.
Acoustic receivers anchored in lines at the bottom of the ocean “listen” for marine animals carrying acoustic transmitters (tags). Each tag transmits a unique signal, a “ping,” which is logged by receivers when the animal passes within range.
Data from the receivers give researchers insight into animals’ movements, migrations, behaviours, and survival over the course of the tag life. This information feeds into management and policy to ensure sustainable practices so that future generations can benefit from ocean and aquatic resources.
Tagging a Lobster!
OTN tags and tracks Atlantic lobster as part of studies to determine lobsters’ seasonal movements and stock abundance in the Canadian and U.S. Atlantic. Adult lobsters are tagged on shore and then released into the ocean and tracked for approximately one year, or until the lobster moults and discards its shell.
Tagged lobsters are detected by lines of acoustic receivers along the Atlantic seaboard. Receivers are retrieved manually by OTN personnel and the data is downloaded to reveal lobsters’ movement patterns and timing.
The Halifax Acoustic Telemetry Line
The Ocean Tracking Network Halifax Line is an acoustic array made up of 256 acoustic receivers and stretching over 200 kilometres from Chebucto Head, Nova Scotia, to the edge of the continental shelf. This acoustic line tracks north-south movements of tagged animals including sharks, seals, salmon, and other fishes.
Methods of Data Collection
Although bottom-moored acoustic receivers are the primary method of data collection, tracking data can also be collected using gliders and even animals themselves.
Gliders are autonomous marine vehicles that patrol the ocean recording oceanographic measurements like temperature and salinity.
The Ocean Tracking Network deploys two Slocum Gliders to monitor physical and biogeochemical variables in the ocean. They move up and down in a sawtooth pattern in the water column at an average speed of 1 km/hour. They carry a modified acoustic tag that can pick up and store detections of tagged animals within range. Slocum gliders have detected tagged grey seals, Atlantic salmon, and sharks.
The Wave Glider is another type of autonomous glider used to collect oceanographic data. A surface unit carries scientific instruments, weather radar and communications systems, while oscillating wings on the underwater “sled” use wave motion to propel the floating unit forward. The glider does not use any fuel and is solar powered except for a backup battery. The Wave Glider’s primary mission is to offload bottom-moored receivers which store data from animal’s tags.
Keep ‘track’ of OTN: tweet us or follow us @OceanTracking