Effect of harvest method and timing on yield and regeneration of Karengo (Porphyra spp.) (Bangiales,Rhodophyta) in New Zealand

Commercial interest in harvesting wild stocks ofPorphyra and concern for this prized resource by the Maori community highlighted the need to investigate the impact of harvest method and timing onPorphyra beds. Harvesting trials were carried out at two locations near Kaikoura (South Island) and one in Wellington (southern North Island) between June 1987 and September 1987. At each of five sampling sites, ten replicate sets of four quadrats were used to test the effects of harvest method and timing on yield and regeneration. The method of harvest had a major effect on the extent of regeneration: in quadrats in which thePorphyra had been cut with basal portions left intact there were harvestable plants within two months, whereas in quadrats which were cleared of allPorphyra there was very little growth after the same period. Harvests in the latter half of thePorphyra growing season gave greater yields at all sites except Wellington. Several species ofPorphyra were found to exist at the Kaikoura sampling sites and a single, different, species at the Wellington site. There were site to site differences in the yields.