Scripps Institution of Oceanography graduate Zach Cabading writes on the importance of solid scientific data when assessing sea lion tension at La Jolla Cove. 

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The latest videos of sea lion harassment at La Jolla Cove have driven some wildlife advocates to call for closing down The Cove to all humans, much as the adjacent Point La Jolla has been closed since 2023.

Community dialogue has disintegrated into online arguing, influencer advocacy and a climate in which the loudest voices have no real background in marine science.

In order to restore science to the conversation, it’s important for the public to understand what information we need to determine whether something is or isn’t happening in the ocean. Good science relies on gathering a much larger suite of data than what people may realize or currently rely on.

In the ongoing tension at The Cove, in which some contend the beach should be closed for sea lion protection while others strive to keep it open for human access and still others want the beach open for limited access for swimmers and divers, two claims are often tossed around: sea lions are overpopulated and sea lion pups are dying at high rates due to human interference.

These claims are not scientific. Let’s examine each below.

Are sea lions in La Jolla overpopulated?

The context:

The sea lion overpopulation argument, which continues to be put forward at public meetings with some claiming there are upwards of a thousand sea lions in and around The Cove, stems from 2013, when scientists became worried about unusually high numbers of sea lion strandings and pup deaths throughout California.

The science:

Historically, there has been a correlation between marine heat waves and high numbers of dead pups. But in 2013, no marine heat wave had yet been detected, leading some scientists to hypothesize that overpopulation was the main factor.

Later that year, a severe marine heat wave was indeed identified, which came to be known as “The Blob” and scorched California’s ocean from 2013 through 2015, killing primary producers and starving many species across all levels of the food web.

The sea lion deaths were linked to The Blob, NOAA concluded.

Sea lion populations have gradually rebounded since the 1972 passage of the Marine Mammal Protection Act and again since the 2013-2015 marine heat wave, though La Jolla Cove is a Marine Protected Area with federal protections and MPAs have been found to be more resilient against heat waves than unprotected areas.

However, we still don’t have a strong, scientific understanding of how the sea lion population ebbs and flows. Here are questions we still need to answer:

• How many sea lions enter or leave The Cove at a given time?
• How many sea lions are dying from starvation versus other causes?
• How are prey populations at La Jolla Cove?
• How are prey populations in neighboring areas?
• Are prey populations at La Jolla Cove diminishing? If so, has that been caused by the sea lions or other factors like heat waves, pollution or disease?

None of the above questions has been thoroughly studied in La Jolla. For that reason, there’s not nearly enough data to suggest or even define “overpopulation.”

Is human interference causing a high number of pup deaths?

The context:

Throughout the 2026 sea lion pupping season (mid-May through September), there were numerous claims that over 40% of sea lion pups had died at La Jolla Cove, and that the deaths were caused by human interactions.

The science:

Pupping season is still ongoing, so there hasn’t been a final count on the number of living versus dead pups.

Provided data by some sea lion advocates shows 56 births and 6 deaths at the La Jolla rookery. That’s a mortality rate of about 10%, which is average: 10-20% of newborn pups do not survive.

La Jolla Cove saw 21 births and 4 deaths (19%), according to the aforementioned counts, while Point La Jolla had 35 births and 2 deaths (5%), though these numbers are still in flux and not final.

Some advocates have pointed out that more pups have died at the crowded La Jolla Cove than the closed Point La Jolla, which is their proof that humans are the cause.

But the sample size is very small, and the numbers have not been calculated for sampling error, a necessary step.

One sampling error example might be if a pup was born at Point La Jolla to a mother who then dies from predation (killed by a predator) or starvation, and the pup has no choice but to venture into the water to look for food. The pup fails to find food and winds up on the beach, deeply malnourished and approaching death. The pup is counted as a death at La Jolla Cove, though its struggles began at Point La Jolla.

Accounting for that single pup, the mortality rate at La Jolla Cove drops from 19% to 14%, skewing data and creating a problem.

Counting dead pups is one thing, but concluding the pups were killed by human interference requires much more substantial evidence. The questions that must be answered first:

• Have necropsies been performed on the dead pups to determine the exact cause of death?
• Has the mother’s location been tracked?
• Are adult sea lions dying, too? In what numbers compared with pup deaths?
• Are scientists tracking the movement of the pups?

The point is, we don’t have enough data to understand the mortality rate or what’s causing it.

So what should we do?

The point here isn’t to suggest that we shouldn’t be worried about the sea lions, or that we shouldn’t do anything about the ongoing harassment.

The city of San Diego needs to commission long-term, site-specific research to better understand the sea lion rookery so we can figure out the best way to protect it and ensure we don’t wrongfully punish the community of swimmers and divers who responsibly enjoy La Jolla Cove.

In the meantime, we should take measures to prevent harassment of the animals; specifically, empowering Park Rangers to set up barriers (cones and tape) to separate the crowd from the animals and to take enforcement action against those who ignore the barriers.

Let’s remember that science is a good compass and we should follow it, letting the scientists – and not the social media mob – undertake more of that work.

Zach Cabading is a Scripps Institution of Oceanography graduate in marine biodiversity and conservation who is engaged in efforts to improve Marine Protected Area management and other preservation work. The views expressed here are his own.