"We have a fisheries management regime that is based around sustainability so quota is allocated for the total allocated catch, and the total allocated commercial catch.
"Every time someone is out there poaching they are stealing off commercial guys, and they are stealing off recreational fishermen."
Hawke's Bay Sport Fishing Club captain Neil Price said crayfish poaching usually happened around this time of year.
Sometimes people would pull up other people's cray pots: "They have names on them, because that's part of the law, but other people will pull them up and see if they can get away with it."
Asked if they had received, or were investigating, any such reports, an MPI spokeswoman said they regularly received reports of suspicious fishing behaviour, a lot of which were unsubstantiated.
"These reports cover a range of allegations including allegations of crayfish poaching. We do not disclose publicly what we do with that information nor do we publicly disclose the nature of our operational responses to allegations that require investigation and follow-up.
"We would like to encourage people to continue to provide us with information on suspicious fishing activity no matter how minor that activity may seem."
Although people might be scared to come forward, Mr Nash encouraged anyone with information to provide it to MPI, "or pass it on to me and I will certainly make sure MPI gets hold of it".
• To report suspected illegal fishing activity, such as poaching and illegal trade of seafood, call MPI on 0800 476 224.