In Europe, fishing is generally quite targeted.  Fishermen know what they want to catch and use the appropriate methods and techniques.  Despite this, when they bring their nets in, they often find other fish and marine organisms mixed up with the target species: this is what is called the by-catch.

Everything in the net has to be sorted and only the fish that can be sold are kept.  The rest are returned to the sea, where they stand little chance of surviving after the shock of being hauled to the surface. These are what are called discards.

Depending on the area the fishermen are operating in, and the kind of gear they are using, discards can make up 10 to 60% of the catch, and sometimes more. This represents an unacceptable waste of resources, at a time when many fish stocks have been depleted by intensive exploitation.