This was a week stream running through kanuka-dominated bush. There was a pool right next to a camp kitchen, I saw as many as four eels at a time, between 0.4 and 1.0m long at a guess. Think they probably get fed scraps a bit. Water quality is good if the number of EPT invertebrates is any indication. Pretty sure long, rather than short-finned, you can see in the first pic the dorsal fin is longer than the ventral if you look closely.