Those fishing in the area spoken to by the Otago Daily Times were confused about the rules and under the impression no licence was needed when fishing on the river past the bridge at Taieri Mouth where the river meets the ocean.
Fish and Game Otago operations manager Ian Hadland said the idea no licence was needed below the bridge was a bit of ''local folklore'', which was contributing to high numbers of illegal fishers in the area.
''It's a combination of good weather and rumoured good catches, which has drawn just about every man and his dog on to the lower Taieri River and that's been coupled with a misunderstanding about where a licence is and isn't required.''
''If people are targeting trout or salmon then there is no question that a licence is required and even if they have got gear that can take trout or salmon then one is required.''
The area under Fish and Game jurisdiction extended 500m out to sea from the river mouth and only those ''legitimately'' trying to target fish other than salmon or trout could fish without a licence.
Fish and Game had spent the last couple of years educating people about the rules, but was now going to take a ''hard line'', which meant seizing gear and writing offence notices.
''The most recent case there was three guys in a boat; they had three trout on board and they were trying to claim you don't need a licence to catch trout, which is just not the case.''
Between 20 and 30 warnings were issued in the area last year and in the past couple of weeks it had caught out four offenders, which was a lot for such a short amount of time.
''It's a bit of a hot-spot for us ... and we need to make the point that a licence is required.''