A model applies lipstick backstage during the “We Love Flamenco” fashion show in the Andalusian capital of Seville January 14, 2015. The show will run until January 18. (Photo by Marcelo del Pozo/Reuters)

The photo project was done for the organization Fishlove and included some other U.K.-based celebrities posing in the buff with critters ranging from bass fish to sharks. Its goal is to raise awareness of how overfishing is destroying the oceans. The release of Gillian's nearly nude pic, which was snapped by French portrait photographer Denis Rouvre, is timed with a European Parliament vote on banning destructive forms of deep-sea fishing in the Northeast Atlantic. The Fishlove organization is trying to rally voters to sign a petition ending deep-sea trawling – which, according to scientists, is negatively impacting the fish population and their habits – and Gillian solicited signatures in a Twitter post. Photo: “Fish Love” Project by Photographer Denis Rouvre. Gillian Anderson. (Photo by Denis Rouvre)

A model walks the runway at the Hakaan Spring Summer 2012 fashion show during Paris Fashion Week on October 4, 2011 in Paris, France. (Photo by Nathalie Lagneau/Catwalking/Getty Images)

A view motorists have grown accustomed seeing, a military truck made by Oshkosh Corp. is taken for a test drive Thursday, April 11, 2013 in Oshkosh, Wis. Faced with deep cuts in U.S. military spending, and the end of the wars in Iraq and Afghanistan, Oshkosh Corp. is laying off 900 employees in its defense division based in Oshkosh. Approximately 700 hourly workers at the state's largest manufacturer will lose their jobs in mid-June, followed by approximately 200 salaried employees through July. (Photo by Mark Hoffman via The Journal Sentinel)

Models pose backstage at the Celia Kritharioti Spring/Summer 2012 fashion show at One Mayfair on March 20, 2012 in London, England. (Photo by Ian Gavan/Getty Images For Celia Kritharioti)

A model backstage before the Issa London runway show at London Fashion Week Spring/Summer 2012 on September 17, 2011 in London, England. (Photo by Tim Whitby/Getty Images)