Marine mammals in September
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Marine mammal events in September:

• Bue whales and humpback whales continue to feed on swarms of krill, but by the end of September, all three animals will be less common.
• Bluefin tuna migrate northward along the coast along with warm oceanic water. They often feed along the edges of eddying tendrils of warmer offshore ocean water that flow toward the coast.
• Several types of dolphins (common dolphins, Risso's dolphins, and Pacific White-sided dolphins) become more abundant in August and September. Some white-sided dolpins move northward along the coast, following the bluefin tuna. Some of the female Pacific white-sided dolphins may be accompanied by baby dolphins just a few months old.
• Populations of California sea-lions increase and reach a yearly peak in September and October, as adult sea lions (mostly males) make their way northward the Central Coast after mating in Southern California (especially on the Channel Islands). They stop to moult, feed, and hang out at prime spots on offshore rocks and human-made structures, with especially large colonies in Monterey Bay, Ano Nuevo, and at the Farallon Islands.
• Young Steller sea lions (born in June) begin to forage on their own. Adult male steller sea lions leave the Central Coast in late August or September, but the females and young may stay until October.
• Harbor seals finish molting on Central Coast beaches and head back out to sea to hunt the wide variety of prey available at this time of year, including market squid, octopus (red octopus near shore?) young rockfish, white croaker, cusk eel, hagfish, and other bottom-dwelling fishes.
• White sharks congregate and stalk yearling elephant seals around Ano Nuevo and other elephant-seal breeding grounds. Not surprisingly, September is prime season for shark attacks on people along the Central California Coast. This high-risk season continues until October or November.
• Sea otters mate all year, but mating is most common between July and September, after the main crop of young otters (born in Jan-Feb) have been weaned.