Mr Mason said the fishing industry was definitely "feeling it".
"Some [operators] have more resources with bigger vessels able to go further out but some are really confined to the area of the exclusion zone. Those guys are really affected," he said.
"But the really great thing is that without exception, they all really just want to get on and do their job and carry on running their business."
Mr Mason said fishing-related businesses such as bait outlets and fishing equipment stores were among those hurting.
There was concern for local sports fishing clubs, which traditionally held large fishing tournaments as their main source of income, if Rena spilled more oil.
Work and Income New Zealand provides support services to businesses and their staff when they are faced with sudden change, such as a reduction or loss of business.