<P> Pier 39 was first developed by entrepreneur Warren Simmons and opened October 4, 1978 . </P> <P> On December 22, 2017, the Federal Bureau of Investigation arrested Everitt Aaron Jameson, a 25 - year - old former Marine, on suspicion of planning a terrorist attack in the Pier 39 area over Christmas . </P> <P> California sea lions have always been present in San Francisco Bay . They started to haul out on docks of Pier 39 in September 1989 . Before that they mostly used Seal Rock for that purpose . Ever since September 1989 the number of sea lions on Seal Rock has been steadily decreasing, while their number on Pier 39 has generally increased . Some people speculate that sea lions moved to docks because of the 1989 Loma Prieta earthquake, but the earthquake occurred months after the first sea lions had arrived at Pier 39 . It is likely that the sea lions feel safer inside the Bay . </P> <P> Although the reason for their migration to the pier is unclear, the refurbishing of the docks in September 1989 required the removal of all boats from that area, leaving large open spaces for the sea lions to move into . Once the project was completed, boat owners returned, but did their best to navigate around the sea lions; no efforts were made to encourage the new guests to leave . By the end of that year, fewer than a dozen sea lions frequented the docks at Pier 39 . By January 1990, their numbers had increased to 150 animals . Owners of the 11 boats docked there began to complain about having to avoid the animals who can weigh up to half a ton, and odor and noise complaints began to pour in . News coverage caught national attention, and the sea lions began to attract tourists . Advice from The Marine Mammal Center was to abandon the docks to the animals, and to relocate the boats elsewhere . </P>

Why are there sea lions at pier 39
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