So, I'm on the quest "Those Chippy Fish" and need to defeat Wharf Rats in Westminster Skyway to collect Albion Potatoes. After defeating four ships and collecting no potatoes, I decided to board the ship and fight it out to see if that brought me more luck. Well, wouldn't you know, that Wharf Rat Ship was crewed by Frog Pirates!! All four enemies were frogs -- no wonder I didn't collect any potatoes.
I suggest that these Wharf Rat Ship crews should always have at least one wharf rat in order to make this collection business more fair.
NOTE: The next ship had a crew of 3 rats and 1 frog - I collected 1 potato. Still need five more.