http://www.immi.gov.au/skilled/general-skilled-migration/gsm-reforms.htm

The English language requirement for GSM applicants nominating a trade occupation will be increased to a minimum of 6.0 (Competent English) in each of the four components of the International English Language Testing System (IELTS) test. This increase in the IELTS score brings the English language requirement for trade occupations in line with other occupations for GSM visas, with trade occupations previously exempt from GSM changes introduced in September 2007.

475 487については下記の様に記載されています。

For the provisional GSM visa subclasses, the threshold English language standard will be raised from an average score of IELTS 5.5 to an average score of IELTS 6. The change will affect applicants for the subclass 475 Offshore Skilled – Regional Sponsored and subclass 487 Onshore Skilled – Regional Sponsored Visa.

なお、上記記事は現時点で入手可能な情報に基づいたものです。ビザ申請を検討中の方は常に最新の情報をご入手下さい。