Thursday, November 5, 2009

Philopatry and migration of Pacific white sharks

Fascinating reading coming from The Proceedings of The Royal Society this week (click on image) with tracking/DNA data from a multi year effort at the Farallons, Point Reyes and Ano Nuevo off the coast of California.

Paper Highlights

"Hawaii is likely to be an important foraging area for white sharks. Extensive use of waters surrounding the Hawaiian island archipelago in winter and spring was evident from 13 satellite tag records (22% of tags with offshore tracks) and five acoustic tags (10% of 2006 and 2007 deployments) detected opportunistically by receivers stationed near the islands of Oahu and Hawaii (together comprising six males, six females and six unsexed individuals) (figure 1). The most precise geopositions and acoustic records from Hawaii included Argos endpoint transmissions (n = 8) with location errors of 150 m s.d. (Teo et al. 2004) and acoustic tags detected at fixed locations (n = 5). These occurred in slope and near shore waters along the entire 3000 km archipelago from the big island of Hawaii extending through the Papahānaumokuākea Marine National Monument to Laysan Island and Midway Atoll (electronic supplementary material, figure S2). While this distribution includes areas with colonies of endangered monk seals (Baker et al. 2007), detailed dive records from four recovered satellite tags (three females and one unsexed; three separate years) indicated that the dominant behaviour, when not transiting (Weng et al. 2007), was a precise diel vertical migration, between the surface and 600 m, consistent with foraging within the deep scattering layer community (Shepard et al. 2006) (electronic supplementary material, figure S3)."

Read study here.

1 comment:

Expat in Germany said...

Kudos to Spain for taking a leadership role in shark conservation. I hope other countries will follow their example.