Whall does not claim the yelp to be only under the ownership of Black shnatymen. Note under his heading "Nigger Songs" (p.121-current edition)
"Both these musical tricks (yelps & grace notes) were freely used by untutored Bnglish bakllad singersof folk songs & such, & are not solely negro. A similar trick was the long "ah" at the end of a verse, which is as old as Shakespeare."

Also see Doerflinger (page X of the Preface) for more of stylistic "hitches, grace notes, high breaks, unexpected stresses & holds & embellishments-variations as Captain Tayluer called them".

Also see Doerflinger's discussion under the chapter heading "The Rise of Shantying" (97p.) with specific mention to the Negro shanyman , his singing, his effect on other shantymen

You may want to also take note of the difference of the origins of sea ballards or forebitters & check out of those songs that have survived what are of anglo decent & what percentage is of Afro-American or Afro-Caribbean.
My belief is that while one (White) sung shanties for work & the other (forebitters) for pleasure, the other (Black) sung shanties for both work & pleasure.

I have to go now

Barry