a number of clear/white jellies (moon jellies?) around the dockside at Port Adelaide, South Australia

The date's approximate (within a month or so either way) since I'm reporting this from memory. But it was winter, early afternoon, we took a Port River cruise and while the boat was waiting at the dockside I observed quite a few jellies (and cut-up parts of jellies, presumably from propeller damage) in the water around the boat. The attached photo was taken at the same location, of jellyfish that looked the same as these ones, but on a different occasion.