Bummer an expensive way to learn, but the best thing to do in the future is leashes (If you don't want to loose it lease it).
I have leases on all my rods when out in the yak and as yet (touch wood) have not lost one in the 14 years I have kayaked. Mad mine from old style phone cords so they're light enough to leave on all the time (even casting) Here are some images to give you an idea. If you don't want to make one most kayak shops do have them for sale.