Kazaa and Morpheus — two popular file-swapping services — had 15 percent fewer users during the week ending July 6, according to Nielsen/NetRatings. The decline translates to about 1 million fewer users on Kazaa. About 41,000 fewer users signed on to Morpheus and the iMesh file-sharing service that week.
The firm tracks a specific number of people who sign on to the services from home and extrapolates the data to estimate how many people use the services at least once in a week.
"With the negative publicity and threat of steep fines, some surfers appear to be backing off," said Greg Bloom, a senior Internet analyst with the firm. "However, with millions of loyal users, these applications aren't likely to go off-line in the near future."
Bloom said the data so far merely suggests a possible link between the threat of lawsuits and the apparent dip in file-sharing traffic. And seasonal factors, such as the holiday weekend, could also skew any trend. A better determination will be possible when all the data is in for July, he said.
The Recording Industry Association of America, which represents the major recording companies, said last month the industry would soon begin suing individuals engaging in online music file-swapping.
Record companies blame music downloading and CD burning for lagging sales in recent years and hope that by going after users directly, they curb traffic to the sites.
StreamCast Networks, the company behind the Morpheus software, said it had not detected any decline in user traffic.
"What we're seeing is that users are actually staying on the Morpheus client longer per session," StreamCast CEO Michael Weiss said. "We can pretty much tell usage by our bandwidth, and our bandwidth has been pretty constant."
Sharman Networks, which owns Kazaa, did not have an immediate comment.