Officials say a record number of sea lions have gathered at San Francisco’s Pier 39, one of the city's most iconic tourist attractions (or tourist traps, depending on who you ask) this week.

Pier 39 harbormaster Sheila Chandor counted more than 1,000 sea lions there this week, per the Associated Press, the highest number in 15 years. Usually, there are about 300-400 sea lions in the winter, reaching up to 700 in the spring.

They’re reportedly flocking to the docks to feast on above-average populations of anchovies and herring before the onset of mating season next month.

"They are fueling up for the mating season,” Chandor told the AP. "It's spring. They are ready to rock and roll down in the Channel Islands, and we're a nice pit stop with some great seafood."

At the Channel Islands, nomadic male sea lions find families to mate with. The animals migrate up and down the coast every year, and first start appearing at Pier 39 after the 1989 earthquake, per NPR. The piers had been rebuilt after being damaged, but boats hadn’t yet been docked, and sea lions moved in. Marine biologists are still trying to figure out exactly why it’s such a hot spot, but it could be due to the fact that the water in the Bay is warmer and draws higher concentrations of fish.

Regardless, the herd drew large crowds of tourist this week, and owners of nearby stores and restaurants reported increased sales from foot traffic. However, there might be one small problem: Sea lions can weigh up to half a ton, and city officials also told AP that the barges where sea lions typically rest were not intended to support a weight beyond a certain limit. The recent increase in sea lion numbers is apparently putting them to the test.

Feature image via Getty Images/angelique shepherd.