Some years, over summer, very large kahawai schools will hang around the mouth of the Waimakariri River for weeks on end. Other years they seem to come and go. Sometimes there is a school there even though there isn’t much bird activity. When big kahawai schools are at the mouth of the Waimak there is usually at least a dozen anglers there chasing them most evenings.
Sure kahawai are present off the other rivermouths most of the time over summer. Particularly the Rakaia River. I have also caught kahawai trolling from a boat off the Waimakariri River mouth. It is always worth heading down to the end and having a go provided