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Researchers:

Richard Fitzpatrick, Andy Dunstan and Monique Matthews 
- "Undersea Explorer", Port Douglas, Australia.

Latest Video : TAGGING VIDEO - 9.8megs streaming .wmv

Introduction:

Sharks are being exploited in fisheries world-wide, with little sustainable management effort. Home range, breeding and growth parameters for reef sharks are poorly understood, yet essential for their conservation.

Osprey Reef is an isolated seamount in the Coral Sea off the northern Great Barrier Reef, Australia. This study of a resident population of whitetip reef sharks, Triaenodon obesus, at the North Horn of Osprey Reef has been conducted since 1995.

Individuals within the population have been identified, tagged and measured. A number of mature females have been tracked to give information on their daily and seasonal movement patterns and home range.

Aims:

  • identify all individual whitetip reef sharks within a population to enable monitoring of movement patterns, growth and reproduction

  • determine growth rates for whitetip sharks in the wild

  • determine a reliable method for tracking whitetip reef shark movements

  • record the daily and seasonal movement patterns and identify home ranges of whitetip reef sharks at Osprey Reef

  • identify the birthing areas for whitetip females and the nursery grounds for juvenile whitetip sharks at Osprey Reef

Methods:

Identification of individuals:

External diagnostic features such as white fin markings, long term scars and pigment spots allow visual identification.  Individuals are caught and injected with a subcutaneous microchip identification tag (AVID) through the thinner dermal layer of the dorsal saddle.

Capture of individuals:

Sharks are attracted to an enclosed bait and the required individual is then roped by the tail and swum to the surface for measurement and tagging.

Growth rate measurements:

Standard measurements for sharks (P.R. Last and J.D.Stevens) are taken as the shark is held immobile on the vessels dive platform

 

Internal transmitter implant:

Local anaesthetic (xylocaine) was injected to an incision site and a 3 cm incision was made in the shark's ventral side just off the mid-line and between pectoral and anal fins. An intermittent pulse transmitter, Vemco V16-6H (69 kHz signal), was sterilised, inserted and the incision sutured.

Pictorial of implant sequence


Shark Tracking

Intermittent pulse transmitters, were implanted to the animals’ main body cavity. Mature females were initially chosen to gain data on breeding times and to locate birthing areas and habitat sites for newborn pups. Data logging receivers, were deployed underwater with a permanent receiver at the North Horn site and other receivers placed at strategic distances from North Horn to track movement patterns. Transmitter tagged animals were detected when within 300-500 metres of the receive


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Queensland. 4879.
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