Erotica boom affects genre book sales
The recent boom in sales of erotic fiction is "cannibalising" the rest of the UK book market, The Bookseller has said.
The trade magazine said print sales of other fiction genres were down year-on-year, including crime novels, which have fallen 20%.
Other genres to suffer declines include science fiction and fantasy which is down 25% and horror, down 30%.
Eight of the top 10 bestselling novels last week were works of erotica.
The fiction chart continued to be led by EL James's Fifty Shades trilogy, which originally started as a work of online fiction.
Although sales fell by more than a quarter from the previous week, the three books sold nearly 340,000 copies altogether.
The only two non-erotic novels in the mass market fiction chart were Lee Child's latest Jack Reacher thriller, The Affair, and John Grisham's The Litigators.
"The whole book market this year was suffering because of the growth of the digital market with print books losing money to ebooks," The Bookseller's Philip Stone told the BBC.
"When Fifty Shades came out it was such a phenomenon that sales grew for a few weeks but at the detriment to other sectors of the market.
"It's a case of lots of people buying Fifty Shades to see what the fuss is about and not buying other books."
Mr Stone added erotica was now stealing sales from the rest of the book industry as publishers scrambled to take on new titles to make the most of the current boom.
"Publishers haven't really taken erotica seriously and have never had it on their books," he said.
"So they've been looking at other self-published authors and seeing what's being talked about online to snap them up as soon as possible."
Non-fiction sales also appear to be affected by the erotica trend, with sales of hardbacks down 16% year-on-year and paperbacks down 8%.
However, sports books have seen a boost in numbers thanks to the London 2012 Olympics with titles by medal winners Tom Daly and Bradley Wiggins making the top five in the non-fiction charts.