Mythical creatures made real: San Diego’s grunion run

I was first introduced to grunion in an ecology class my sophomore year at the University of San Diego – we were told we’d receive extra credit on our third midterm if we went out and documented...

Correspondent Maggie Scholle observes a grunion run, a seasonal phenomenon of fish spawning that lines the Southern California coast.

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I was first introduced to grunion in an ecology class my sophomore year at the University of San Diego – we were told we’d receive extra credit on our third midterm if we went out and documented a grunion run. Small and sardinelike, grunion are fish native to Southern California that spawn on the beach during spring tide in the months of March to September. Spring tides refer to the highest of high tides, happening on full and new moons. 

In late May of 2019, three of us drove to Silver Strand state beach — runs are supposed to be the biggest on broad, secluded beaches — and waited for the fish to come. The second hour of the second night is said to bring the biggest spawns, and we sat on shore, three out-of-staters poised to be reminded of why we came to college in California. The wind was blowing onshore in a familiar midwestern way, but none of the breaking waves brought fish with them, only thick salt spray. We walked further down shore, first year environmental science majors not yet possessing the language to explain the patterns of longshore drift that pull sediment (and grunion) north up the strand. After an hour of searching, our most significant sighting was a lone juvenile man-o-war, a small jellylike hydrozoan that from a distance appeared to be a small newspaper bag washed up at the high tide mark. We left grunionless, but relieved to see a different creature from ecology class rendered real instead of beach litter. 

Two years later, on a springtime full moon, I reconciled that I couldn’t leave California without having taken part in a proper grunion run. Early March is the first publicized run of the year. In 2021, this meant the day after daylight saving time, when midnight feels like 11 p.m. and it’s a little bit easier to be fully awake and present in the dark. We saw flashlights about halfway down the beach and turned away from them and started toward the jetty. The first discernable change was the texture of the sand. At high tide, it’s soft and gooey, the kind that your feet fall into and leave an oblong imprint, more hoof-like than human.

We saw one fish, about 400 meters north of the lifeguard house. It wasn’t a good omen. Grunion have a built-in safety system: if the first fish don’t get swept back in the ocean by the tide, the rest of the group will identify a threat onshore and a run will not occur. I was convinced we’d witnessed precisely that, a lone scout on the beach signaling an apparent danger. As we walked further south, a group of plovers scurried out behind a breaking wave. Dun brown on top with white underbellies, the small birds looked just enough like the silvery sides of a grunion to be the real thing. They moved in a pack, though they scuttled over land much more nimbly than a fish could. Still, I wanted to believe they were grunion: if these fish could spawn on land, maybe they really could move like they had legs?

The plovers ran east, and we turned toward the breaking waves to see the silvery sides of hundreds of fish illuminated by parking lot lights. Finally, grunion had materialized in the incoming water, glistening in a way that was distinctly the product of layered scales, and not deceptive feathers.  Almost immediately, they surged up against the sand, burrowing vertically into the soft sediment and laying eggs. For every fish flopping onto land, there was another head visible, buried fins-down in this perennial ritual. Further south, a network of holes was visible: we had found the grunion mid-run, the glistening orange eggs filling the indentations indicated. The grunion on the sand sound like wings, their tails beating against the thin laminate of water as the waves rush back down the sloped sand. 

Catching grunion is a form of sustainable fishing in California: With no bait, lines, or lures, California Fish and Wildlife rules state that they must be caught with one’s bare hands, and strictly prohibits the catching of excess fish. A hunter approached us, armed with only a red cooler and small flashlight. Upon seeing us, they turned back — it may be an unspoken rule of grunion hunting that it is best done in isolation. Perhaps it was our turn to go, too, and just let the fish be.  

The next day, we went out again. The third day is sometimes as good as the second, research tells us. The weather felt strikingly similar to that grunionless May of 2019, with strong winds, giant kelp washed onto burgeoning dunes, and eggshell-white foam spray surrounding the kelp beds. The winds were strong enough to knock out a transformer, breaking the link between the electric grid and the entirety of the glorified sandbar that is Mission Beach. In the full darkness the grunion could be apart from humanity, spawning in actual darkness like evolution intended them to. We walked down to the jetty, and they were there — scattered across the shore with the force of the waves, but still digging holes with only tails and fins, still silver against the night-black sky, still making their world go on.

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