Dolphins generate in large amounts with ocean ruin structures

I'm having a very similar issue, though unrelated to structures. They seem to be spawning in hordes as of the new snapshot, though I'm not sure whether or not that has to do with spawning over time or if they all spawn at once.

Also affects other ocean structures including ocean monuments. In fact, it may not be tied to structures at all.

I just had the same issue and was no where near an ocean structure. I started building to max height to work on a mob grinder and my game started to chug. So I dropped back down and was greeted by hordes of dolphins below. Luckily I leave cheats active for just such situations, so I ran /kill @e[type=minecraft:dolphin] and it returned 3,206 dolphins were present. 

That's a different bug. MC-130197

Please provide seed and coordinates.

I found a ruin that spawns almost 50 dolphins. The seed is -2240190304131579005 and the coordinates are 32 56 272.

now there is no dolphins that point to treasure it seems

@unknown -> MC-130092