I've fished the Deep North of Australia for barramundi on more than a dozen trips over the last 25 years. Barra are cool fish (think Indo-Pacific snook), but they live in tough neighborhoods. Much of the Top End lacks large prey animals that crocs prefer (e.g. wildebeests crossing that river in Africa), so they subsist mostly on fish and crabs. They are programmed to eat the largest animals they can find, including the odd shark:
https://www.youtube.com/watch?v=dcAYb-w5oVY(BTW: if you ever have the chance, visit Kakadu National Park east of Darwin where this video was filmed, as well as the first half of "Crocodile Dundee". A wonderful place to take the family . . . but not necessarily a location to fish from shore.)
Crocs may have primitive brains, but their ancient DNA gave them cunning. An unwary land animal (e.g. a 'roo, wild horse, or a buff) that waters in the dry season at the same place at sunrise or sunup will eventually find a large reptile hanging off their nose. The crocs spot the game animal in the distance, then submerge at the same spot 24 hours later in wait for the animal to visit again. One of my guides alerted me to this trait one year and urged me to not only stand on the rocks a few vertical feet above the ocean's edge, but also to not fish from the same perch twice in a row. The next day, I moved 50 feet away from the hot spot and was casting away when I saw two nostrils and then an evil eye and head slowly emerge in the first light . . . about 10 feet away from where I had been the previous day.
On another trip, I was fishing in a crystal clear river and standing knee deep, chucking my lure as far as I could to reach the dropoff where the barra congregated. I took another step out to where my knees were covered, and the guide told me to get back. In colorful language, he said that a 4 meter croc at full power could cover the 60' or so that we could see into the river in a couple of second. If I was in deeper than below my knees, I wouldn't be able to turn and run through the shallows and up the beach fast enough to escape. The crocs are simply so fast in the water, and for a short distance on land, the big game animals they occasionally see (and always stalk) often can't get away.
In summary, Mother Nature programmed crocodiles to eat anything and everything, with bigger being better. I treat these animals with lots of respect when fishing in waters they inhabit.
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My many visits to BC and Alaska suggest that "people" don't register on a bear's natural menu. That's fortunate. As a diver, it's always cool to see a shark and they, too, typically are curious or ignore people. But there's NFW I'd go diving if there were salties around.