Make your own free website on

Downs Rebreather Site

La Paz Research

General Prism Photos
Detailed Prism Photos
La Paz Research
Other Cool Pics - Page One
Other Cool Pics - Page Two
Related Links
Contact Me

Pelagic Assemblies and Hammerhead Tagging
October 2002 to November 2003

Funding for portions of this project were provided by NGS, UCMEXUS, UC Davis, and private parties. Boats and suface support provided by CIBNOR. We also wish to thank Steam Machines, The Cortez Club, and many others and for thier logistical support.













Our initial trip was to verify that the techniques and technology would work. Satisfied with our first effort, we returned to the area to apply additional acoustic tags and the more sophisticated PAT tags. We spent most of our time working and little time filming, so we didn't bring back much footage. And following the concrete laws of Murphy, the most interesting events took place while the cameras were off. Oh well, I still think what we did film is pretty interesting, and the tagging efforts were successful.
Note for those that may be concerned:
The speargun was not for hunting the sharks. Sal occasionally used the gun for more distant shots, and I preferred a Hawaiin sling for the close up work. Both worked well in different situations. The tools have modified tips that allow us to plant tag anchors in the dorsal muscle of the sharks. The sharks are not seriously harmed in the process, and after the initial bolt following a tagging sequence, they return to their normal schooling behavior.
Here is Sal waiting for unsuspecting sharks to swim by.
This was one of our first attempts at tagging the sharks. Our techniques quickly became more refined, and we regulary got much closer to as our work progressed.
As you can see, with the rebreathers, some careful planning, and good techniques, we were able to get very close to these majestic animals.
This is an early shot of one of several schools we observed coming in very close.
Here are a few more interesting photos of the sharks and a few giant mantas that are now very rare at the seamount.

Here are a few select photos from our first visits to the El Bajo Seamount in 2002 to study scalloped hammerheads (Sphyrna lewini) and many other pelagic species using the Prism closed-circuit rebreather. All dives were conducted by Salvador Jorgensen and Jeremy Downs.  These dives were part of an ongoing effort by Dr. Arturo Muhila, Dr. Peter Klimley, Salvador Jorgensen, John Richert, and Jeremy Downs to survey the community surrounding the seamount and pelagic migrations of some of the larger species. The rebreathers were used to apply both acoustic and archival tags on the sharks.