As reckless and irresponsible Sea Shepard is, you have to admit he is drawing attention to the issue. That being said, I don't really think it's the most effective (or safe) way to go about it.
The past few seasons the Sea Shepard and her crew has been only a nuisance, but last years catch was only 1/5 of the allotted quota. This means the pocket of the trawlers and fishing companies were severely affected. This year might be the year the Japanese whaling ships says F IT. Just like you and I, these Japanese fishing crews have bills to pay and when you are paid by the weight Something is going to have to give.
Sea Shepherd does what everyone else is too scared or ignorant to do. If the rest of the world had the balls that SSCS does, and the same willingness to put it all on the line for what they believe is right, the world would be a much better place today.