After a helpful comment on one of my old YouTube videos (where I reviewed a Crayfish trap)... I found out that the expandable, net trap I had was actually illegal to use now as it can easily trap otters also.
Here is a PDF document I found from the Enviroment Agency, titled:
"Using the Right Trap - A Guide to Crayfish Trapping" - http://dl.dropbox.com/u/218966/Forum...h-trapping.pdf
It obviously has some useful guidelines if your interested in trapping Crayfish and it enlightened me on how my trap isn't exactly appropriate.