Complex sentence: Anti-whaling legislation passed by the Australian Government applies to Australian territorial waters, however Australia's claims of sovereignty over the Australian Antarctic Territory--and thus sovereignty over Australian Antarctic territorial waters--are recognised by only four countries, not including Japan.
Split into simpler sentences: Anti-whaling legislation passed by the Australian Government applies to Australian territorial waters. However, Australia's claims of sovereignty over the Australian Antarctic Territory--and thus sovereignty over Australian Antarctic territorial waters--are recognised by only four countries, not including Japan.