Complex sentence: Sea Shepherd has received support for its tactics against fishing, whaling, and seal hunting from quarters such as media personalities, while their violent tactics are sometimes opposed even by those who denounce whaling, such as Greenpeace and the governments of Australia and New Zealand.
Split into simpler sentences: Sea Shepherd has received support for its tactics against fishing, whaling, and seal hunting from quarters such as media personalities. The violent tactics of Sea Shepherd has been opposed, even by those who denounce whaling, such as Greenpeace and the governments of Australia and New Zealand.