There's this wonderful thing called the DMCA - the Digital Millennium Copyright Act - which requires websites to remove content that is stolen intellectual property. This includes photos, sketches, written documents, and many other forms of digital media. Nearly all websites which host media content will have a DMCA takedown report form so you can report stolen images electronically.
Most recently, a lot of folks in the Taxidermy community here have had issues with an Anti-Fur group on Facebook stealing their images illegally to use for their own bullshit agenda. Here is the form you need to have the image taken down: https://www.facebook.co