According to Hugill, the words here were often fitted to the hauling song Ane Madam. This version, from Lars Erik Sandin's songbook, is dated 1844. The words are also found in Swedish railway worksongs.

Hugill and his Swedish source seem to have missed the older references found in early 19th-century German sources which themselves seem to trace back to choruses of "Fidulin". Clint Hulton provides his sources in an excellent summary:

This Swedish capstan song was obtained by Hugill from the collection _Sång under Segel_, edited by Sternvall. Sternvall evidently got his Swedish text from the song book of a sailor, Lars Erik Sandin, dating to 1844. As for the melody he chose, apparently it came from a collection called _Filikromen_ (ed. by "Ståhl", 1876) -- which used a different text, and which claimed that most of the lyrics known to that editor were of an 'obscene' nature. (I have located it under the title, "Och alla de brev, jag till henne skref, Fridolin.")

I have not run across recordings of this or any other Swedish version of this song. However, suspicious of the spelling "Fredolin," and having changed it to the more likely "Fridolin," I discovered many references to German versions of it (though Hugill did not mention any).

A German-language collection called _Die lieder aller völker und zeiten..._, edited by Hans Grabow (Hamburg, 1890), has a section for "Schifferlieder". All the songs in the collection have been translated and refashioned into German verse. An untitled "Schifferlied" has the refrains of "Fridolin/Rosabella Fridolin."

A note says that the song was composed by "Brassier" in 1819, and that it comes from the comedy "Der Weltumsegler". And it indicates that it should be sung to the melody of the Italian song "O pescator dell' onda". Here's a link to some sheet music of that popular song, which has the refrain "Fidulin/ Fidulin, lin, la".

As I understand it, it is taken to be a traditional (?) Italian fishermen's song.

Yet Grabow's version was not the first German one. Here's a German poetry collection of Gerhard from 1826 with an adaptation much closer to the original, "Fidelin, lin lin [la]"

At some point (i.e. by the 1840s, if Stervall claim about the Swedish sailor book, above, is reliable), the refrain must have gotten changed to the more "Northern European" sounding "Fridolin", and "Rosabella" was added -- suggesting the name of a vessel.

Other sources show that the Italian song, at least, enjoyed great international popularity in/by the 2nd and 3rd decades of the 19th century.