![]() ![]() SPOT tags transmit a signal to the Argos satellite array whenever the dorsal fin breaks the surface of the water. For studies of shark movements, Smart Position or Temperature Transmitting Tag (SPOT tags) are commonly attached to the dorsal fin. External attachment makes satellite tags prone to damage and premature shedding. These tags utilize radio transmissions, requiring the tag to have contact with air to send data (hence satellite tags must be externally attached). Satellite tags are detectable over broad geographic areas and remotely relay information to satellite arrays. Surgical implantation of a coded acoustic transmitter manufactured by Vemco Ltd.ĭivers deploying an underwater receiver manufactured by Vemco Ltd. The records from receivers at different locations are combined to create an overview of shark movement patterns. When a tagged shark comes within detection range of a receiver (detection radius is up to 1 km depending on transmitter type), its unique ID code is recorded, together with the date and time. The receivers are deployed on subsurface moorings and continuously listen for transmitters, 24 h a day 365 days of the year. These transmitters are then detected by underwater receivers stationed at various locations on the sea floor. This system consists of uniquely identifiable ultrasonic transmitters that are surgically implanted into sharks and fishes to ensure longer retention. Passive acoustic monitoring uses the same basic transmitter-receiver technology as active tracking but is for longer-term (months or years) studies. This example was manufactured by Vemco Ltd, Canada. The depth and temperature information is encoded in the acoustic pings transmitted from the tag.īluespine unicornfish (Naso unicornis) with externally attached acoustic pinger. More sophisticated versions of these tags include onboard sensors (typically pressure and temperature) to provide depth and water temperature information from the fishes track. This process is known as ‘active tracking’ because the researcher actually follows the fish to find out where it goes. Pingers are attached to sharks and fishes which are then followed in a vessel equipped with a hydrophone and receiver. This was the original type of fish tracking tag. ![]() The ‘pinger’ produces ultrasonic pings that can be heard using a hydrophone (underwater microphone) and receiver. The simplest version of the acoustic transmitter is the ‘pinger’. These run the gamut from the most well-established types of electronic tag to prototypes on the very frontiers of this type of scientific research. On this page we provide brief descriptions of the different electronic tags used in our shark and reef fish studies. pH sensors) to provide new insights into important aspects of shark & fish behavior such as how often they feed. One of the frontiers in electronic tag science is development of new types of sensors (e.g. For example, depth and temperature sensors can tell us whether a shark lives primarily in the warm surface waters of the ocean, or is a frequent visitor to deeper, colder zones. Sensor information helps biologists to better understand the environment in which animals live. The most commonly used sensors measure depth (pressure), temperature, salinity (conductivity) and light levels. Many electronic tags obtain environmental information via a suite of sensors. If PATs are physically recovered then the full record can be downloaded from memory. ![]() For example, Pop-Up Archival Satellite Tags (PATs) store large volumes of data in onboard memory and summarize data for lower-volume transmission to satellites. ![]() Some electronic tags combine both datalogger and transmitter in a single device. The major trade-off between these two approaches is dataloggers generally provide much larger quantities of data than transmitters, but datalogger recovery is not guaranteed, hence the desirability of remote transmission. Dataloggers store all of their data in onboard memory and must be recovered from the animal for downloading. Transmitters send data from their host animal remotely via sound or radio waves to a receiver. We use two broad classes of electronic tags (transmitters & dataloggers) in our studies. ![]()
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