A paper written by Peter De Joux and myself was published in the Marine Technology Society Journal, the first page can be seen here. The paper describes the tracking system we built and use to track rig sharks in Porirua Harbour. You can access it at the link below, or email me for a copy.
http://www.researchgate.net/publication/269764979_A_Tracking_System_for_Sharks_in_Shallow_Water