This whaling song likely originated in New Zealand around 1860-70 and was preserved by oral traiditon. In print, it first appeared in Neil Colquhoun's New Zealand Folksongs: Songs of a Young Country (1973). Colquhoun collected the tune in 1966 from F. R. Woods who in turn learned it from his uncle (along with the New Zealand song "John Smith A.B."). Circumstantial evidence suggests this uncle may be D. H. Rogers, a teenage sailor/shore whaler of the early-mid 19th century who later supplied the song "John Smith A. B." to The Bulletin in 1904. The song was first recorded by The Song Spinners in 1967.
The song reached critical fame as part of a 2021 TikTok meme centered around collaborative performance and/or breaking out the song at non-traditional times & locations. The recordings typically emphasized singing together despite the social isolation of the COVID-19 pandemic, leading to an unlikely resurgence of The Longest John's recording, and its approachable harmonies, three years after its release.
The song describes the whaling ship Billy o' Tea encountering a right whale. The crew hopes for the arrival of the "Wellerman" – an employee of the Weller brothers (whose ships sold provisions to whaling boats). Joseph Brooks, George, and Edward Weller moved from England to found their establishment at Otago Heads, Dunedin, New Zealand in 1831, though they ran the company from Sydney. The sudden decline in whale population brought about the firm's bankruptcy shortly into the 1840s.
Whaling in New Zealand continued throughout the 18th and 19th centuries as it was discovered that Pacific Ocean whales arrive off the west coast of New Zealand in early May each year. Whaling stations were set up along the straits these whales passed by, and the workers were paid in clothing, spirits, and tobacco.
This article is indebted to John Archer's New Zealand Wellerman folk song page which contain excellent background information.