Salmon overrunning rivers & streams

Holy mother of Salmon!! I enabled doMobSpawning when the story is completed and on my test run, the waterways are absolutely overrun with schools of salmon. There are so many, that it is causing a considerable fps drop when near the water. (looks like Silvermist has her work cut out for her)

Not sure if this is already posted, I searched, but couldn't find a clearly labeled issue about this.

Edit: Look at the total number of entities, around 1,000