I'd say it was more likely singers would not offer them if they were asked for songs. I don't think many of the contributors were sea-going people although Aberdeen and Dundee were famous ports, but more for fishing. There is very little evidence that fishermen or British whalermen used shanties. Some no doubt used the skills they had to go further afield like the famous Storm family from Robin Hood's Bay.

It was mainly west/south coast Atlantic seamen who knew the shanties, hence the frequent mention of Liverpool. I've never heard a shanty that mentions Hull or Yarmouth and I'm not aware of shanties being collected in those places. The only shanties I ever recorded there were from an old Cape-Horner who was on the grain and meat ships but he was from London.