Posted by: brookenado | September 23, 2013

One summer, two shows: Grunion & Red Tide

Dear readers,

This summer brought two other, equally wondrous reasons why I love living on the coast, so let’s stick with the ocean theme for another week.  We all know that nature has some pretty spectacular sights for show.  It doesn’t matter where you are geographically, there is always something amazing to see.  Well, a couple of such inspiring natural phenomenon here revolve around the Pacific Ocean, specifically on the beach.

lolcat flabbergasted

Accurate lolcat is accurate. You will feel similar the first time you see these.

The first are these little fish called grunion.  What could be so exciting about a fish?

Would you believe that it’s the way they lay their eggs?  Sure, it sounds weird, but then think about how fascinated we are with sea turtle nesting.

sea turtle egg hatchling

You can tell me you have zero interest in this…but I just won’t believe you.

Ok.  So these silver fish, about six inches or so in size, only lay their eggs in late spring through summer, and timed very precisely around a lunar schedule.  On the night of a full moon or new moon, people will gather on the beach for a “grunion run”.

fish california grunion

This is the California Grunion (photo by Rob Johnson)

On the right set of waves, scouts will appear first on the sand before disappearing with the next rush of water coming up and receding.  Deemed safe, these fish will come up on the shore with the water in sets.  They flop around finding a good spot in the wet sand, and the females dig a hole with their tail fin, somehow managing to get completely vertical in the sand with the top half of their body sticking up.

female grunion laying eggs

She’s dug her nest and is laying her eggs – doesn’t take more than thirty seconds for her!

Then, they lay their eggs.  A male will then fertilize the eggs in the nest.  And just like that, these little holes in the sand across the beach are homes for hundreds of new grunion to be born!  After laying their eggs, the females wriggle out of the sand and flop towards the oncoming water, and disappear.  It’s a truly amazing ritual to watch, and I will never forget the first time I saw them, hundreds of silver flashes of reflected moonlight.

california grunion nesting egg laying

The males make sure the eggs are fertilized. Nice work, guys.

In recent years many others have started to come to the beach by us at night for these grunion runs.  On one hand (a more snobbish hand, sorry), this frustrates me as it takes away from the moment when so many people are greedily snatching up fish as soon as they see them.  On the other, I see lots of delighted children and I’m hopeful that these kids who have such an experience with the grunion will continue to protect them and their habitat in the future, for their kids to experience on a summer night.

Plus, it turns out there is an off-season for grunion runs, which is currently in effect for the first two months of their spawning season.  This means that people can go to see the grunion, but are not allowed to take any of the fish during these runs.

fish grunion run california

Did I mention that you can actually see the hundreds of tiny orange eggs in the sand if you look into a nest?

Ok, so grunion are pretty neat little fish.  Next up?  The “red tide”.  Bit ominous sounding, I know, but let me tell you…it’s just really, really cool.

The red tide refers to naturally occurring algal blooms that can happen all over the world.  Different environmental factors depending on the region have the potential to cause this accumulation of algae off the coast, which coupled with specific types of plankton turn the water a brown-red color.

ocean red tide san diego algae bloom

Image by Diane Varner

Great.  Brownish water.  What’s so special about that?  It’s brown-red during the day, but the real fun of the red tide is seen at night.  Every once in a great while, the red tide off the coast of San Diego features bioluminescent plankton, phytoplankton called Lingulodinium polyedrum.  Yes, the water turns fluorescent!

bioluminescent red tide san diego ocean waves night

Crazy! And beautiful! Photo by Don Haake

Disturbance in the water, a.k.a. waves, triggers the bioluminescence from these microorganisms, and it is spectacular.  People will make a trip out to the beach at night to “ooo” and “ahhh” at the bright, greenish-blue glow in the water.  I like to think that the red tide is nature’s own firework show.  My family was so excited when they spotted the light scattering along the whitewash of the waves when driving home a few weeks ago.

san diego la jolla shores ocean red tide bioluminescent

A shot of the red tide over at La Jolla Shores

As soon as they walked in the door and I got wind that it was, in fact, a bioluminescent red tide, I pressed pause on “Harry Potter and the Half Blood Prince” (right at the most crucial part, no less), threw on a jacket, and went straight to the beach!  It was late, but there were a few other groups that made their way to the water as well.  I say the red tide is like a firework show, because it’s a similar feeling.  I stood with these folks I don’t know, watching a light show, delight evident in our pointing and gasps as another wave crashed and lit up.   Like I said, very, very cool.

san diego red tide ocean bioluminescent surfer

If it appears from water disturbance, then a surfer would really be putting on a show!

And that’ll wrap things up for this post.  Quick note – none of these photos are mine, we haven’t been yet able to capture these night occuring events so well as those who did in the featured photographs.

If you are ever in Southern California over the summer, do yourself a favor and look into these natural coastal phenomenon.  You are in for a real treat if you make it out on a good grunion run night, and a spectacular show if the red tide happens to be a glowing one.  Thanks for reading, cheers!  Until then…

Mischief managed



  1. I can’t believe that I’ve never seen either of those events! I am inspired to pay more attention to our environment. Thanks!

    • Of course! I love sharing these things, because they are just so darn cool 🙂

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