Subject: Satellite tagging

bcooper@neaq.org
Tue, 16 Feb 1999 22:41:36 -0500 (EST)

 
> I am currently a student at the University of Manchester, England 
> and am very interested in how sea mammals, particularly 
> whales, are tagged and have a few questions. 
> 
>  - How are the tags deployed?
>  - Once the tags are attached to the whales how are they powered? 
>  - How do the satellite tags work?
>  - How do you choose which whale to tag?
>  - Why would you want to tag whales in the first place?

Dave,
	Good questions.

The method for deploying the tags depends on the situation. For
stranded/rehabilitated cetaceans, small animals you can get your hands on,
the tags are attached to the dorsal fin. In the case of free ranging
whales, tags are darted similar to biopsy sampling. For more information
you can also check out the archives as Leah Gerber answered a similar
question some time ago.

The tags are powered by batteries. The size and type vary by the size of
the tag, desired monitoring period, and amount of information the tag
will be sending.

Satellite tags are quite high tech and there is a good description at the
Service ARGOS site www.argosinc.com. The tags themselves can be simple,
sending a signal all the time, or they can be a bit smarter and only send
when the tag surfaces. Tag data is encoded in the data stream. Postions of
the tag are calculated by the satellite based on Doppler effects and
number of recieved signals. The more signals the satellite
"sees" in one pass, the more accurate the location.

Which whale to tag? That would depend on the goals of the project.

Tagging whales gives us a huge amount of data on the
lives of these animals. It gives us a window into thier lives that we
could never see otherwise. Information such as how deep do they dive? How
long do they routinely stay submerged? Is there a depth they like to
travel at? When we are not watching them, where do they go? With good tags
and correct placements we can learn that information and more.

Good luck,
Bob Cooper.