The research that went into Copyright “Rustling” in English-Language Translation: How Translators Keep (and Lose) Rights to Their Work—Data from Translations Published in 2014 reveals that translators in commercial English-language publishing lose copyright to their work more than one-third of the time. When it comes to university-press publishing, the statistics are even more dramatic: publishers fail to recognize translators’ copyright in nearly four titles in five.
The practice of copyright “rustling” has become common among even some of the largest U.S. and U.K. publishers of translations.
In addition to providing analysis of more than a thousand translations published in English in 2014, the report also discusses what copyright “rustling” suggests for translators’ loss of contractual power and proposes strategies for resistance.
Download a copy here: Copyright “Rustling” in English-Language Translation.
ProvenWrite: Expert IT>EN Translation 
The figure of one third is a gross underestimate. Most non-fiction publishers no longer assign copyright to the authors let alone to the translators! As for copyright in university press publishing, I doubt if one-tenth even acknowledge the existence of a translator, let alone offer them copyright in their own work.
Well, you’re welcome to do your own research, if you feel you have access to more accurate information — in fact, I encourage it! But the information at my disposition didn’t support the contention that “most” nonfiction publishers take copyright and, in fact, the distinction between “nonfiction publisher” vs. “fiction” publisher isn’t logical. Many publishers do both. University presses are, without question, some of the worst offenders. I found that they take copyright 8 times out of 10; you say it’s 9 in 10. That might well be true, but I don’t have the data. If you do, please publish them.