I've done an awful lot of fishing between Ratchet and Northwatch Hold and I can guarantee there are tons of fishing nodes, including many different spots that the floating debris can spawn. I've noticed that the node locations are always the same, but the kind of node varies randomly (a school of some kind of fish, or floating debris).
There's 2-3 nodes around the place where Isha Awak spawns, any of which can be floating debris, and sometimes multiple debris at once. There's also some more nodes on the beaches near Dustwallow Marsh (but on the Northwatch-side beach) (I noticed these nodes seem to either be Firefin Snapper or Oily Blackmouth schools). I've seen debris many times in the water right near where Baron Longshore spawns too.