Earthquake Effects On Abalone Habitats And Populations In Southern New Zealand

The 2016 Mw 7.8 Kaikoura earthquake lifted 140 km of coastline on New Zealand's South Island by up to 6.4 m. This caused extensive mortality and destruction of habitat critical for early life stages of blackfoot abalone Haliotis iris (called paua), a species of cultural and commercial importance. The fishery for paua was closed, at considerable financial loss to local communities. This study determined the extent to which habitats and populations of paua survived along the coastline. With aerial imaging, the coast was categorised into broad habitats at a 10 m scale. This was used to select areas for in situ assessments of paua populations and specific habitat features at 26 sites over 1.5 yr. We quantified key habitat features to identify correlates and potential drivers of paua abundance and distribution. We found that despite extensive habitat degradation from uplift, erosion and sedimentation, abundant paua in size classes < 30 mm shell length indicated that successful settlement and juvenile recruitment had occurred soon after the earthquake. Paua up to 170 mm shell length also survived in shallow habitats. A generalized linear mixed model showed that paua were negatively influenced by the degree of uplift, and positively associated with the cover of unconsolidated layered rocks. Juvenile paua (< 85 mm) abundance was greatest at sites with < 2.5 m of uplift. There was further recruitment 1.5 yr post-earthquake and evidence of good growth of the previous year's cohort. Despite major disruption to this coastline, there appears to be very good potential for recovery of paua and the fishery.