The hint is a picture of a cod and "cod" is the cryptogram key. The plaintext message is

"When sun rays crown thy pine clad hills",

the first line of the song "Ode to Newfoundland" written by Sir Cavendish Boyle.

The cryptogram is a Vigenere cipher with plaintext encrypted one letter at a time by repeatedly adding the letters of "cod" to the plaintext. For example, the first six letters are encrypted as:

 

plaintext

 

key

 

ciphertext

w (22)

+

c (2)

=

y (24)

h (7)

+

o (14)

=

v (21)

  e (4)

 +

  d (3)

=

  h (7)

  n (13)

 +

  c (2)

=

  p (15)

  s (18)

 +

  o (14)

=

  g (32 mod 26 = 6)

  u (20)

 +

  d (3)

=

  x (23)

...

 

 

...

 

 

...