The current trend is for carp and big fish weigh slings to be floating and this new Force 8 Floating Recovery Sling does just that alot cheaper than many of it's competitors:

Essential recovery for fish – no caring angler should be without one
The safest way to retain fish for photography
High density foam keeps recovery sling afloat
Folds in two for easy storage and transportation
Long secure retaining strap totally safe
Soft fish friendly material
Another winner from TFG