Source : Wright, Joseph English Dialect Dictionary
web : https://eddonline4-proj.uibk.ac.at/edd/main.html

YAGGER, sb. Sh.I. A clandestine purchaser of
things unfairly disposed of. Sh.&Ork.1 The same word
as Jagger.

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JAGGER, sb. Sc. Nhb. Dur. Cum. Wm. Yks. Chs.
Der. Lin. Shr. Also in forms jaager, jager Sh.I.; jigger
Der.2 nw.Der.1; yaager Sc. (Jam.); yagger Sh.I. (Jam.)
[dʒa·gə(r, Sh.I. also jā·gər.] 1. A travelling pedlar; a
hawker, esp. a fish-hawker.
Sc. The name ‘jagger’ is applied to a pedlar, or the bearer of a
wallet or leather bag called a ‘jag,’ Yks. Wkly. Post (Dec. 24,
1898); (Jam.) Sh.I. ‘I am a jagger,’.. replied... a stout, vulgar
little man, who had indeed the humble appearance of a pedlar,
called jagger in these islands, Scott Pirate (1822) v; The word...
properly signifies a person who purchases goods, chiefly fish,
contracted for by another (Jam.); Dey wir sic a hubble wi' boys,
jaagers, an' men, Sh. News (July 15, 1899).
2. A boat, which takes the first catch of herrings to land
in the deep-sea fishing.
Sh.I. The doggers attached to them [herring busses], named also
Jaggers or Yaggers, were swifter sailers, being intended to run
home with the herrings first caught. After the Jaggers are all
dispatched, the busses continue fishing till they make up cargoes,
Hibbert Desc. Sh. I. (1822) 215, ed. 1891.
Hence Jager-steamer, sb. a steamer for the transport
of herrings.
Sh.I. There might have been from 100 to 120 of the Dutch craft in.
No Germans at that epoch, and no booms, nor jager steamers,
Sh. News (June 25, 1898).
3. A carter or carrier, esp. a man who makes his living
by carting for other people; one who sells coals in small
loads. See Jag(g, v.1 7.
n.Cy. (Hall.) Cum. A carrier, when loads were carried on
the backs of horses. The word was never applied to a carrier in
carts here. It is seldom heard now; but a road on Stanemore by
which pack-horses used to travel is still called ‘t'jagger rwoad’ (M.P.).
Chs. A poor labourer that carries coal from the pits in Flintshire
to Chester market, on a small horse (K.); Chs.1 Chs.3 s.Chs.1 For
the horse in best condition owned by huxters or coal-jaggers
residing at Threapwood, Worthenbury, or Shocklach, Advt. of
Flower Show (1886). n.Lin. You're the best jagger that ever run'd
round Wivilby Green, Peacock R. Skirlaugh (1870) III. 229.
Shr.1 So John Ivans is turned jagger, I 'ear! Shr.2
4. A pack-horse driver.
Dur. Gibson Up-Weardale Gl. (1870). n.Yks.3 Der. N. & Q.
(1876) 5th S. v. 474; Der.2, nw.Der.1
Hence Jagger-horse, sb. a pack-horse.
n.Yks.3 Der. N. & Q. (1876) 5th S. v. 474.
5. A carrier of ore from the mine to the smelting-mill.
Der. Until the introduction of wheel carriages in the Peak...
the only mode of conveying goods and merchandise from one part
of this country to a distance was on the back of pack-horses, or,
as they were here called, ‘jagger-horses,’ and the drivers or conductors,
‘jaggers.’ These jaggers were employed in conveying
lead ore from Eyam, and mines in the locality, to the smelting-houses
in the neighbourhood of Sheffield, returning at night
loaded with sacks of coal, N. & Q. (1876); 5th S. v. 474; Grose
(1790) MS. add. (M.); Der.1 Der.2, nw.Der.1
Hence Jagger-galloway, sb. a pony with a peculiar
saddle for carrying lead, &c.
N.Cy.1, Nhb.1 Obs. Cum., Wm., A ‘jagger-galloway’ may yet
be heard of as employed in the mining districts (M.P.).
6. A small dealer in hay.
Der. The word ‘jagger’ is used in the Peak, not confined to a
person who sells cartloads of coals. I have heard it gen. applied
to men who purchased hay, and then carted it for sale to Manchester
or Stockport ─ such a man is called a ‘hay jagger,’ N. & Q.
(1877) 5th S. viii. 518; Der.2, nw.Der.1
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Source : Century Dictionary web : http://triggs.djvu.org/century-dictionary.com/splash3.html