A sea lion colony is noisy in a way that a photograph cannot convey. The barking that carries across the water is mostly males holding territory and females and pups locating each other, and a mother returning from days at sea finds her own pup in a crowd of hundreds by voice, with smell used only to confirm it at close range.

The Coronado Islands sit just across the border in Mexican waters, a few miles off the coast, uninhabited apart from a small naval detachment and left largely to the wildlife. That is the reason for the numbers. There is no development, no beach access and very little disturbance, so the colonies here do what colonies do when nobody interferes with them.

California sea lions have been increasing steadily for decades, which makes them a genuine conservation success and, in places along this coast, an argument. A recovered population of large, intelligent, extremely capable fish-eaters does not always coexist comfortably with the people who fish the same water.