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. By thinking like a shark, he means avoiding swimming with their preferred prey, such as seals or shoals of mackerel or herring.We use two broad classes of electronic tags (transmitters & dataloggers) in our studies. Sharks are not very interested in people, said Hueter, noting there have been very few encounters leading to injuries in Canada. "You have to think like a shark, and you have to remember that the ocean is a wild place, not a swimming pool," he said. While there is need for care, there is not a great deal of need for concern about sharks, said Hueter. "The shark came by, had a look at them, disappeared out of visibility, and then 20 or 30 seconds later came back for another look and another look." Staying safe "They had several encounters with, likely, the same shark," said Harvey-Clark. There was another encounter earlier this week, this time involving a charter boat with a dozen divers in the water. "The shark came in from deep water, had a look at her, she threw up her arms, and it turned around and hightailed it out of there," he said. Earlier this month a solo diver saw one in St. Scarring and other markings can also aid in identification.Īnd Harvey-Clark isn't the only one spotting sharks off the South Shore. Individual sharks can be identified by unique markings on their pelvic fins. ![]() Harvey-Clark will be using the pictures he took to develop a tool for identifying individual sharks. Halifax-based shark researcher, diver and veterinarian at Dalhousie University Chris Harvey-Clark is hearing about more great white shark sightings.
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