This is a 2011 Dutch video on harbour porpoises in the North Sea.
Translated from Ecomare museum in the Netherlands:
In Belgium, the use of two types of gill nets is permanently banned from recreational fishing from this month on. Nature organizations are very happy. They reported that scores of harbour porpoises drown in this type of fishing net. To protect these small toothed whales they started some time ago the campaign Warrelniet. In recent months, they collected 22,000 signatures. Now politics has taken a final decision. Belgian anglers will now have to use other gear.
Young harbour porpoise skeleton in Ecomare museum on Texel: here.