Yes, what you are observing is likely the fall striped mullet run that eventually ends up in the ocean, spawning on the continental shelf November through December. A wise old mullet fishermen Lynn Johnson, of Merritt Island, once told me that during the summer the female mullet are on the west shore of the Lagoon while the male mullet are on the east shore, but they mix it up in the fall as they school together preparing for the ocean migration offshore to spawn. Somehow, I believe some spawning may occur in the Lagoon, like redfish.
Years ago I spoke with the lock master on the C-44 canal that leads from Lake Okeechobee to the St. Lucie River and eventually St. Lucie Inlet. He told me that this time of year (November) he would lock the mullet through the locks from Lake Okeechobee, as if they were an impatient boater, because so many would pill up migrating from the Lake to the ocean. He would then lock them back through to the Lake in the winter and spring when they migrated back the Lake. Continue reading at Capt. Rodney Smiths Blog – http://rodneysmithmedia.com/dr-grant-gilmore-on-the-mullet-run/
