Fish spawning and despawning lags server severely

When more than 128 blocks away from the ocean (at y=62) fish spawn and despawn rapidly (See attached), creating massive amounts of lag for the server, making the game unplayable if a player is in the area.

When a player goes down to ocean level and lets the fish spawn and stay, the problem goes away. 

This is a fairly major issue for our server as it makes playing near impossible in the area.