SIMoN
  Sanctuary Integrated Monitoring Network
Monitoring Project

Fine scale, long-term tracking of adult whites sharks

Principal Investigator(s)

  • Michael Domeier
    Marine Conservation Science Institute
Start Date: October 29, 2009

Although much has been learned about white sharks over the last ten years, there is still much that we do not know about the life cycle of this species in the northeastern Pacific Ocean. The complete migration cycle of adult female white sharks is not known, due to the relatively short lifespan of satellite pop-up tags. Furthermore, without concurrent precision tracking of white sharks from central California and Baja California, Mexico, the level of mixing of individuals from these two regions is unknown. Theoretically, DNA studies could demonstrate that these two spatially distinct groupings of white sharks are in fact one population, when in fact it is the mixing (interbreeding) of just a few individuals per generation that produce the result. I propose to address these questions by capturing and affixing near real-time satellite transmitters to the dorsal fins of 5 male and 8 female white sharks from the Farallon Islands. The sharks will be captured via hook-and-line, raised from the water on a large hydraulic platform and tagged before being released. Data will be collected and monitored over the next 4-6 years, via the ARGOS satellite array. Results will be disseminated to the Sanctuary via reports, and to the scientific community via peer-reviewed publications.

Summary to Date

In 2009 two male white sharks were tagged at Southesast Farallon Island. Near real-time transmitters were attached to the dorsal fin of both sharks. Both of these sharks made their normal seasonal migration to a region in the middle of the Pacific Ocean centered between the Hawaiian Islands and Baja California Mexico. This is the same region that is frequented by white sharks from Guadalupe Island and so is termed the shared offshore foraging area (SOFA). The sharks remained in the SOFA until they returned to the central California region during the summer of 2010.

Study Parameters

  • Tagging
  • Migration/movement patterns

Study Methods

One type of tag we have used to study white sharks is the pop-up satellite tags. Pop-up satellite tags are inserted at the base of the dorsal fin as the sharks are lured close to the boat with large tuna carcasses. After a set period of time the tags detach from the shark, float to the surface and transmit collected data of light, temperature and depth. These tags have remained on the sharks for up to 1 year and have given us invaluable information on the behavior and movement of white sharks including swimming depths, temperatures encountered, daily patterns, and migratory movements. With this technology we have shown that the sharks can dive as deep at 1000 m and that they spend as much as half the year away from land out in the middle of the Pacific Ocean. We have found that sharks tagged at Guadalupe Island spend autumn and winter at the island, begin an offshore migration in late winter to early spring, spend spring and summer offshore between Baja California, Mexico and Hawaii, and then return to Guadalupe Island in late summer. We know that they travel out to the middle of the Pacific Ocean, but what draws them out there is still a mystery.