Sea Serpents: the Cryptid that Wouldn't Die

OK, that's an odd headline, but it just appeared in my brain.  I geuss it works for two reasons. One is that "sea serpents," whatever one imagines them to be, have always been reported and I think always will, at least once in a while,  The other is that I still want there to be something to the legend.  It doesn;t have to be a huge long-necked mammal or a plesiosuar: I'll settle for an oversized eel or elongate shark.   
There are a few touchstone cases from the classic sea serpent tales.  There's the Daedalus sighting in 1848,which might have been a whale (might).  There's the 1907 sighting by naturalists Nicoll and Meade-Waldo,which is the gold standard (and still not really explained.) And there's the 1817 Gloucester serpent, which was reported so many times that even the skeptical Richard Ellis, an excellent analyst of such things,  mused thatit's hard to believe nothign unusual was happening.  
Now, to where I was going with all this.  Dr. Darren Naish, whose Tetrapod Zoology blog is a must-read on matters cryptozoologica, reviews here a book by Robert France that I would review myself if I could afford the damn thing ($77). Disentangled: Ethnozoology and Environmental Explanation of the Gloucester Sea Serpent  suggests the "serpent," cannot be disentangled (my words) from the time, place, and culture of the sightings. Those factors contributed to a run of events when people mistook large marine mammals and debris for large  unknown animals. He thinks it's most likely that net-entangled or line-entangled creature giving rise to monster sightings were most often tuna vs mammals, given high speed, quick-turning ability, etc. Naish is impressed, even though he cautions we still don't KNOW.  I hope to read the book at some pont and be impressed as well. Thanks, Darren!