Biofuels are being used to minimise the amount of fish waste in a number of Pacific fisheries based around the US and Canada, according to World Changing which discusses using fish for fuel.
I can't see any problems with this(beyond the usual worries about overfishing)providing that it is "accidental", and happens with materials that would otherwise go to waste. We have to live in the world we live in and if people are catching fish it has to make sense to reduce the amount of waste from the process. After all if we lived in the stone age its unlikely that we'd let much of a mammoth go to waste if we were lucky enough to catch one.
But the comments about whales are interesting and it is the first time that I've seen those noble beasts of the sea linked in any way with biofuels... if only to say explicitly that they should not be hunted for their oil. And quite right too.
hattip to agricultural biodiversity weblog