- I read this book more than 25 years ago so it's likely 70's or earlier as it was "older" when I read it.  
 - It’s not long, maybe 300 pages?
 - Involves human and other species
 - I believe it was at least one human who was kidnapped (can't remember gender) by aliens off of a boat or some other isolated place (not a house or anything)
 - Aliens pit these harvested/kidnapped species/people against each other in combat on a planet. 
 - It's not great writing and seemed very easy for me even at 10-12 years old. 

I believe it was a female author...