This video from the Netherlands says about itself:
19 March 2016
This morning a live stranded harbour porpoise was found on the Dutch isle of Texel. The young male was found emaciated and with a bite wound on his tail. The wound was caused by an attack by a grey seal. So the little harbour porpoise was lucky to have survived this attack. In the rehabilitation centre he was given the name Sven.
He is now the second patient that is currently under the care of SOS Dolfijn. Exactly two weeks earlier a harbour porpoise stranded on the German coast. This animal was named Nena and is already swimming by herself again. Sven needs to be supported constantly and is too weak to swim.