Completion Strategy:

In this level, you play as Mr. Big Tony.
You fight a bunch of Shotgun wielding ducks in this level.
Duckman Drake to be exact!
These ducks are really powerful and have good accuracy.
Don't go all over the place chasing them, because there are plenty to be killed.
Instead, let them come to you.

- Lenny

Platinum/Fast Time Strategy:

80 kills in the time required... harsh? I think not.
There are 2 spawn points I'm fond of that will get you a secure 80+ kills.
The first spawn point is when you spawn in the toilets.
Grab the Double Shotguns in one of the toilets, and camp facing the entrance.
From there, pump the ducks full of feathers, or lead rather, as they come in.
Sometimes, the ducks will also spawn in the toilets, so be sure to kill them safely.
If you're not confident, you can exit the toilets, and make your way to the stairs that to the spawn point I mention below.
Crouch, and face the actual steps.
The reason this is a good place to camp in, is because most of the ducks spawn points are located near the place.

The other spawn point I'm fond of is when you spawn directly on top of the armour on the second floor.
From there, go into the room just to your left, and grab the Double Shotgun.
Stay there, and shoot the ducks as they come in.
(Make sure you're crouched) Because of the fact that's it's soooooo easy to die in this level, be sure to grab the armour once in a while.

- Lenny