Inclusion of historical perspectives is considered necessary for the comprehensive assessment and management of complex social-ecological systems. Marine conservation biologists have increasingly recognized the value of non-traditional sources such as historical anecdotes as a way to estimate pre-anthropogenic baseline conditions in wildlife populations. The present study demonstrates that examination of eyewitness sightings of unidentified marine objects (UMOs), that were thought at the time to have been sea serpents of the “many-humped” or “string-of-buoys” typology, reveals that Australian marine fauna may have been victims of entanglement in fishing gear for a much longer period than is generally assumed. If this illation is correct, the onset of entanglement in Australia predates by many decades the advent and use of plastic in fisheries and other maritime operations in the later half of the twentieth century. Additionally, given the alarming global promulgation of pseudoscientific rhetoric, the present study offers a pedagogical opportunity in which to contrast alternative explanations of folklore and cryptozoology versus those of euhemerism and scientific parsimony.