The colors represent country of origin and/or species. I think if memory serves me correctly, one band is for Canada and the other band is a US Fisheries & Wildlife ID band. The colors denote where in the country they are from and I believe it's the letter/number sequencing that identifies them but I'm not sure if they can tell if it's male or female or if they look up the code in the database and find it there. I think the US band is so we can register them in their database as well but don't quote me on that, my memory isn't that great!