photo: Hermanus Backpackers via flickr.
Mongabay is pointing out a really pretty cool piece of shark research from Proceedings of the Royal Society B: The great white sharks along California's coast were previously thought to roam far and wide, but we now know that the California population is distinct and hasn't mixed with other white sharks for tens of thousands of years:Remain in One Hunting Area Over 100 Days
Various monitoring methods show that white sharks in the northeast Pacific return to the same spots over and over again, sometimes remaining in one hunting area for over one hundred days.
Oh, and by the way, researchers also tracked five great whites entering San Francisco Bay, presumably seeking out seals and sea lions.
Salvador Jorgensen of Stanford University's Hopkins Marine Station:
The sharks were detected frequently at their chosen site, which means that they are patrolling around there nearly constantly, for long periods of time. They will occasionally visit one of the adjacent sites, but they always come back.
NE Pacific Sharks Descend From Small Group Arriving in Prehistoric Times
As for how far back this population became isolated, the paper says genetic studies indicate that northeastern Pacific white sharks likely originated from a small population which arrived sometime in the last 200,000 years -- and hasn't intermixed with populations from outside the region since.
We Thought California Sharks Migrated Throughout Pacific
Carol Reeb from Stanford University:
If you asked use a few years ago we would have said white sharks found in California probably migrated throughout the Pacific. Now, even though we know they travel great distances, their paths are surprisingly constrained to specific routes.
Read the original: Philopatry and migration of Pacific white sharks [PDF]