Under the circumstances that would spawn a Sea Hound (killing Jellyfish, dropping meat items, fishing, etc) a swarm of 4+ Sea Hounds will spawn. Though sometimes, it seems to be 1-3 Crocodogs instead. I first noticed this on a game with Woodlegs, where killing Jellyfish with the Sea Legs would sometimes summon the swarms. To rule out it just being an issue with the Sea Legs, I then started a second game with Warly to test it, and sure enough, it happened there as well. I dropped a Bacon & Eggs in the water, 4 Sea Hounds. Dropped a tropical fish in the water, one Crocodog. Killed a jellyfish, 4 Sea Hounds. I then started a Wigfrid game and tried to get it to happen using the Meat she starts with. The first couple of times something spawned, it was a single Crocodog. The third time, 4 Sea Hounds.
EDIT: Started a new game, used console to spawn a boat and fishing rods. Seems like when something spawns a result of fishing, it only spawns a single Crocodog, at least that happened six times. Dropping meat into the water, the majority of times, I just got a single Crocodog. But then occasionally, you get a horde of Sea Hounds. Usually four, but one time I got seven! Killing Jellyfish will sometimes spawn the Sea Hounds as well. Is it, I dunno, spawning Crocodogs instead of Sea Hounds most of the time, but the number of Sea Hound opportunities to spawn is held somewhere, and when for whatever reason it does spawn Sea Hounds, it spawns all the ones it missed? Very odd.
As noted above, it's just happening whenever, pre-Home Sea Home, a Sea Hound would have spawned.