Here is a video about a swimmer who was attacked by a Lamprey.
www.animalplanet.com/tv-shows/river-monsters/videos/a-kiss-of-death-lamprey-sucks-jeremys-blood.htm
www.animalplanet.com/tv-shows/river-monsters/videos/a-kiss-of-death-lamprey-sucks-jeremys-blood.htm
Here's a quick information page about Lampreys. It talks about where they were first located, where they live now, and what is being done to get rid of them.
http://www.umesc.usgs.gov/invasive_species/sea_lamprey.html
Overview on Lampreys
http://www.ucmp.berkeley.edu/vertebrates/basalfish/petro.html
Here's an article about how Lampreys came to the Great Lakes and what they eat.
http://www.mnn.com/earth-matters/animals/photos/13-vampire-animals/lamprey
Overview on Lampreys
http://fishandboat.com/anglerboater/2013ab/vol82num4_julaug/07lamprey.pdf