Senior fishery officer Courtney Burn said she had a particular passion for blue cod and she researched them for her masters topic at university.
Ms Burn said they were a very special fish. However, they were facing local depletion because of some behavioural characteristics.
"They don’t move far from their local reefs and they can change sex based on their population dynamics."
Taking either females or males out of the population would lead to depletion in their numbers.
Overfishing of blue cod had left previously abundant numbers very low in some reefs, she said.
"If you take out too much blue cod in an area you’re likely to see a collapse of that population. And the bag limit was 30 per person; it was ridiculously high."
The new bag limit had changed and was dependent on a "traffic light" system.
In "green" areas the daily limit was 15 per person and fishers were required to land blue cod whole or headed and gutted.
In "orange" areas the limit was 10 and required to be landed whole and in "red" areas the limit was just two per person.
Whole fish were required to be longer than 33cm and headed fish needed to be longer than 24cm.
However, Ms Burn said blue cod being used as bait was a hot topic at the moment.
Ms Burn said there is a clause in the Fisheries Act that says it is illegal to possess blue cod on New Zealand Fishery waters unless they are in a whole or gutted state which makes is clear they cannot be filleted.
She said although there was no specific legislation against using blue cod as bait, it was still in contravention of that clause.
In addition, she said people used undersized blue cod as bait.
"It might be the first fish someone catches and they know it does not meet that 33cm limit and so they opt to use that as bait."
Ms Burn said she would often come across repeat offenders who would normally offend for a benefit, which included bartering and trading blue cod for other seafood, such as paua.
She said although some foreigners would be caught offending because they might not know the rules, the majority of the people she dealt with were New Zealanders.
It was important to educate people around blue cod regulations and measuring techniques, she said.
The fisheries compliance team would have a stall at the Brighton Gala on Sunday where they would answer people’s questions and hand out free paua knives.
