Just a thought/interpretation

"Were spearing eels in the month of April
And starving slaves out on Scatterie"

read as

'We're (*we are*) spearing eels in the month of April
And (*we are* - unspoken) starving slaves out on Scatterie'

i.e. - the 'we' are working our butts off trying to catch eels which don't bring in a living,'we' ARE the slaves working for nothing on Scatterie
(from me central-heated house !!!)