The rape of the lock (canto II)

Hi..
I am studying now deeply this poem called (The rape of the lock).. only (canto 2).. So if I need your help please don't hesitate and never neglect me.. and I am so thankfull to you all..

my first question for this poem is:

Love in these labyrinths his slaves detains,
And mighty hearts are held in slender chains.
With hairy springes we the birds betray,............................25
Slight lines of hair surprise the finny prey,
Fair tresses man's imperial race ensnare,

1- who is (his) in the first line?
2-what do we mean by (imperial)?