Yikes, we used to swim in there all the time when my oldies lived on the canal there. They'll be stuck in there now and won't be able to get back through the wier.
Looks like they are turning up for a feed. As a general rule, it is risky to swim in canals for this very reason. The open ocean also has its risks. I have heard plenty of stories about Tiger sharks, and sightings. They love eating turtles and we have plenty of them along the coast. they also turn up when boats are fishing for Black Marlin. At least we don't have crocs down here.
they do look hungry, I'm with you, stick to the ocean.
