In her article in the Hakai magazine (February 6, 2017) Rachel Fritts gives some background about a dead sea monster
“25 feet [7.6 meters] long” and “shaped like an eel” with a “flat” head,
which was captured by the Maine fisherman S. W. Hanna during a fishing expedition off New Harbor in 1880. Hanna decided to toss the body over board. Nevertheless, a report about this ‘monster, published in the Sea-Side Press rose the interested of US American scientists.
Fritts refers to some correspondence between Hanna and the researchers J. M. Allen from Hartford, Connecticut and Spencer Fullerton Baird, US commissioner of fish and fisheries. Unfortunately there is no additional information about these sources.
A sketch of the animal made by Hanna, allows the assumption that “the ‘sea serpent’ he spotted off New Harbor” was actually an oarfish.
Oarfish are to the small family Regalecidae. Found in all temperate to tropical oceans, they are yet rarely seen. The giant oarfish, is the longest bony fish alive, growing up to 11 m (36 ft) in length. (freely quoted from wikipedia)
In the same magazine, published on February 8, 2017, Alexander Deddy looks into the report of a whale drowned by a sea monster:
“Captain George Drevar and the crew of the sailing ship Pauline were off the coast of Brazil in 1875 when they witnessed a battle between two titans of the sea: a sperm whale and a monstrous sea serpent. Over the span of 15 minutes, Drevar watched as the serpent coiled itself around the whale and attempted to pull it below the surface. Occasionally, the battle dipped out of sight, only to rise again. Eventually the serpent prevailed, and the whale was dragged to the dark depths” (Deddy, 2017).
Deddy discusses the hypothesis that in fact the “sea monster” might have been lost fishing geer and marine debris, in which the whale got entangled and by which it was drowned.
An image published in Illustrated London News in 1857 depicts a scene in which a lighthouse keeper saw a sea monster with a head covered in white spots and a tail that stretched 60 meters. Ecologist Robert France suggests it was just a whale with fishing gear trailing behind. Photo courtesy of Robert France
In this context he refers to the books ‘The Great Sea Serpent’ (1892) by and ‘Le Grand Serpent-de-Mer’ (1968) by Bernard Heuvelmans in which sea serpent stories were examined. Based on these works, Robert France, an ecologist at Dalhousie University in Halifax, looked into “sea serpent sightings dating back to the mid-17th century, and found that oftentimes the characteristics of a sea serpent—the presence of a long tail, for instance—were merely inferred by the sailors and could have been trailing debris. In many reports, France found details he thought suggested marine debris had been involved. (…) France says nearly a fifth of the several hundred accounts he analyzed had something that made him suspect it was actually a sighting of entanglement.” (Deddy, 2017)
Further reading: Robert France, Historicity of Sea Turtles Misidentified as Sea Monsters: A Case for the Early Entanglement of Marine Chelonians in Pre-plastic Fishing Nets and Maritime Debris, CORIOLIS, Volume 6, Number 2, 2016.