Just this past week, the beaches of Southern California and Baja Mexico have been inundated by monsters from the briny deep. Well actually only one monster, the Oarfish. But it was two separate incidents! Of course you only need two data points to make a trend, so clearly there must be something wrong with the ocean it these creatures are trying to flee it. Or is there…Before I go on I should really say I am not an Oarfish expert. But what I do know about is currents. And during the past week, the currents around California may have been favorable for Oarfish beachings.
Strong northeasterly winds have been blowing the coast of Southern California since the beginning of last week. For this time of year this is sort of unusual, as the strongest northwesterly winds usually occur from May to July. But it is these fierce winds that cause deep water to be pushed upslope across the continental shelf in a process known as upwelling. Along-coast winds transfer momentum to the sea surface, pushing water which turns and flows offshore due to the influence of the Coriolis force caused by our wonderfully rotating planet. Deep water then flows up and across the continental slope to replace the surface waters that are pushed offshore, causing upwelling! Upwelling is usually a good thing, as it brings up nutrients from the deep to feed all the starving sea beasties at the surface. Upwelling is so important that often major fisheries are located around regions where upwelling occurs, such as off the coast of Chile.But upwelling may not be so kind to the Oarfish. Oarfish are pelagic fish, meaning they like deep water. So conceivably, upwelling currents could possibly drag unsuspecting Oarfish up the slope and onto the beach. While Oarfish in the wild have been observed to be very chill swimmers, this is probably highly unlikely. Upwelling currents really aren’t strong enough to push them onshore. Seriously, if Oarfish were whim to every ocean current their life would probably suck. No offense to phytoplankton or anything,
A more likely scenario is that Oarfish were “tricked” by the upwelling currents to head closer to shore and shallower water when they normally wouldn’t. The bathymetry around Oceanside and Catalina island is complicated and there are many deep canyons that Oarfish could conceivably inhabit. When upwelling pushed the deep water that Oarfish typically like to hang out in up and onto the slope, they might have just tagged along, following environmental cues like temperature, salinity or even food abundance. Why they aren’t tricked onshore during the typical upwelling season is beyond me, but it might have something to do with their population distribution. Oarfish just might not be near the coast during the spring upwelling season.
As I said before, I’m not an Oarfish expert. But the victims seemed to be healthy (one lady oarfish may have been ready to spawn!), so it seems pretty likely that something caused them to want to swim towards shore at which point they weren’t able to overcome the local coastal currents and ended up gasping on the beach. Whatever the cause (and it could be that upwelling is not that cause) last weeks unlucky Oarfish just seemed to have been in the wrong place at the wrong time
In response to the comments below, I wrote this post to suggest a real physical phenomenon for the oarfish stranding as opposed to the plethora of wild speculation that has been invading the internet. I probably didn’t put in enough “maybes” and “possiblies” to convey that properly. Further investigations may prove that upwelling may not be the cause, because that’s the way science rolls. To me it seems that wide-spread naturally occurring process is more likely to have contributed to the beachings than sonar, earthquakes or fracking fluids (if these were true, I would expect more than just two fish of the same species on the beach). I’ve even seen a suggestion that internal waves caused the oarfish to end up on the beach! For the record, I am very dubious about this claim. But regardless, upwelling is a valid and testable hypothesis and I think it would be remiss to not even consider it. Disagree? Comment section is below.