Step 1. You need the scripthook lua plugin. If you don't have this already, download and install it from this link: http://gtaforums.com/topic/789139-vrelhook-lua-plugin-for-script-hook-v/
Also this requires script hook but that should go without saying.

Step 2. Put the file "whalemod.lua" into "..\Grand Theft Auto V\scripts\addins\"
Step 3. F9 to spawn whales. F10 to delete them all after you've created a mountain of whales the size of the whole block.
Step 4. ???
Step 5. Profit