After 28 days adrift, College of the Redwoods’ drifter is poised to reveal some insights into a long-standing mystery. Marine science students at CR have deployed hundreds of drift bottles over the last 25 years. The bottles contain a card asking the finders to record the location in which they recovered the bottle, and send the card back to us.
In that time we have developed a fairly good idea of where California’s coastal currents are likely to carry our bottles. During our storm season, the nearshore Davidson Current tends to transport our bottles northward. We have very high recovery rates during those times in northern California, Oregon, and Washington. On occasion our bottles have made it as far as British Columbia and Alaska. The Davidson Current tends to be best developed between mid-October and mid-February, but southerly storm winds in late spring and early summer often produce the episodic, short-lived appearance of the Davidson Current.
The California Current, on the other hand, sweeps close to shore during much of the rest of the year. Our drift bottles are usually carried southward during these times. If you’ve been following this blog, you’ve undoubtedly noticed that our drifter has been swept over 200 nautical miles southward in the last month, successfully avoiding all of the most common stranding sites. During this time of year, most of our drift bottles are recovered along the Mendocino, Sonoma, and Marin County coastlines (counties that are north of the Golden Gate). Some of the bottles are carried south of the Golden Gate as far as Monterey County. The farthest south any of our bottles have ever been recovered is Big Sur.
Our drifter is now about 40 n.m. offshore along the Monterey coastline and rapidly approaching the latitude of Point Sur. For the last 25 years, the burning question has been, “Where do the bottles go if they don’t strand north of Big Sur?” Two of our bottles were recovered (several years apart) in the Philippines, but we have no other recoveries south or west of Pt. Sur. So, at long last, our drifter is on the verge of shedding some light on the mystery of where the surface currents carry our drift bottles.
Wow, this really is a cool story. One could run a global circulation model to find out the answer. But after studying the circulation the hard way for so many years, actually having a real drifter in the water is so much more suspenseful.
I’d love to see the drifter’s track on a map with all your card data collected over the years. It would be really neat to bring the two stories together at long last.