Meaning "a lazy movement, looking for food"
Used in a poem "Basking Shark" by Norman MacCaig "Collected Poems" (1985).
As you see it was used in 1985, by Norman MacCaig. If you put M00/101S into the Google search you will find the whole poem.
"To stub an oar on a rock where none should be,
To have it rise with a slounge out of the sea
Is a thing that happened once (too often) to me.”