Fisherman on the Kaikoura coast have had their final warning about "telson clipping" crayfish they catch.

Fisheries officers caught 27 fisherman breaching the rules in Kaikoura over Labour weekend.

Kaikoura Fisheries officer Mark Green said around half of those pulled up had too many paua.

"People are still struggling to get their head round the fact that once paua are put in their catch bags or unable to return to their environment, they're classed as taken."

Green said half of those breaches related to not clipping the tail fin of crayfish, which prevents them being sold on.

"Most of them at this stage have been warning letters, but this has now been running 14 months so we're getting towards the end of the warning letter stage and these will be addressed as infringements if it continues."

Mark Green says not knowing about the law, and not having the right equipment for telson clipping will no longer be viable excuses.