Fish Die-Off at Leadbetter Beach Remains a Mystery

Thousands of dead sardines, and some grunion, washed onto the Santa Barbara shoreline — at Leadbetter Beach along Shoreline Drive — last week. 

Beachgoers were bewildered by the piles of dead fish strewn about the sand and seaweed, which were readily feasted on by seagulls and brown pelicans.  

What is particularly fishy is that no one seems to know for sure what killed them, leaving Santa Barbara scientists to speculate about what might have happened. 

Robert Warner, a professor of Marine Biology at UC Santa Barbara, tipped off the Indy when the fish first appeared on Friday, estimating that there were “3,000-4,000 sardines dead on the beach.”  

“No idea why they died,” he wrote, “but if from toxins, that could affect the birds…Could affect public health if they died of domoic acid,” a neurotoxin from algae blooms, “less so if it’s dissolved oxygen. One way or another, it’s a bad sign.”  

UCSB research biologist Robert Miller thought it could be the result of predators, such as dolphins, pushing the fish up onto the beach.“This is not very unusual where you have dense schooling fish and lots of predators attacking — they just end up jumping onto the beach and getting stranded.”  

Grunion, which were found among the dead fish, are a small species of fish that, at this time of year, spawn at night on sandy beaches mostly from central Baja California to Point Conception. UCSB marine biologist Milton Love explained that spawning takes place out of water, “as far up the beach as the fish can wiggle,” around the full moon and new moon.  

Since the full moon was just a few days ago, that would explain why grunion would be in nearshore waters, having just spawned or getting ready to spawn. As to what could have killed them, though, beyond a few guesses, Love said, “I dunno…it will perhaps remain a mystery?”

Sometimes, grunion get stuck behind kelp while spawning and get stranded, Miller noted, but there was not much kelp at the crime scene. In any case, he said, given that it was localized and affected just “schooling baitfish,” his guess is that it was due to “predation on a bait ball,” adding, “Hopefully it’s not a toxin situation.”  

As of Tuesday, Leadbetter smelled like it would on any other day — not great, but not like a bunch of rotting dead fish, either. After the bird’s weekend buffet, the remains were likely reclaimed by the tide. 

The strange phenomenon follows on the heels of a large number of sick brown pelicans being taken into the care of the Santa Barbara Wildlife Care Network. Whether the two events are related, however, is purely speculation as of now.