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)

Harry Potter collectible busts are displayed in the home of Menahem Asher Silva Vargas, after he was presented with a Guinness World Record title certificate for the largest collection of Harry Potter memorabilia, in Mexico City, Monday, September 29, 2014. Silva's collection consists of more than 3000 individual items, including trading cards, wands, and books in multiple languages. (Photo by Rebecca Blackwell/AP Photo)

An attendee makes a video with the new iPhone 16 Pro as Apple holds an event at the Steve Jobs Theater on its campus in Cupertino, California on September 9, 2024. (Photo by Manuel Orbegozo/Reuters)

A Carlsbad,Calif. police officer turns traffic away as flames leap behind him Wednesday, May 14, 2014, in Carlsbad, Calif. Weather conditions that at least temporarily calmed allowed firefighters to gain ground early Wednesday on a pair of wildfires that forced thousands of residents to leave their homes. (Photo by AP Photo)

A fox cub gets up to mischief in a garden in Halifax, West Yorkshire on May 10, 2022. The homeowners say a family of foxes visit regularly from their nearby den. (Photo by Steve Midgley/Solent News)

A man wearing a face mask to help protect from the coronavirus carries a bag of groceries as he walks by a mural depicting an iconic financial market bull statue near the central business district, Monday, April 18, 2022, in Beijing. (Photo by Andy Wong/AP Photo)

A woman pours alcohol from the bottle into her mouth at the Far Hills Race Day at Moorland Farms in Far Hills, New Jersey, October 17, 2015. Young locals in New Jersey catch up with friends from school and college days at the Far Hills Race Day, which started as a fox-hunting event in the early 1900s. Many racegoers first went to the Hunt, as it's known locally, as children, but nowadays it's an alcohol-fuelled party for them. Makeshift bars are set up in cars, with the horses' efforts on the turf sometimes a backdrop to the main event. (Photo by Stephanie Keith/Reuters)

People get covered with powdered colors to celebrate the Holi festival in Bangalore, India on March 21, 2019. Holi is observed at the end of the winter season on the last full moon day of the lunar month Phalguna, which usually falls in the later part of February or March. (Photo by Jagadeesh N.V./EPA/EFE/Rex Features/Shutterstock)