Evans, K. J. (2019). Urban ecological restoration: Do effective design guidelines exist for restoring instream habitat for the longfin eel within New Zealand urban coastal rivers?. Lincoln University.
Completed as part of a Masters of Landscape Architecture at Lincoln University, the purpose of this thesis was to investigate whether effective guidelines exist for restoring instream habitat for the longfin eel (Anguilla dieffenbachii) within New Zealand urban coastal rivers. This investigation was important because longfin eels are a key endemic species within Aotearoa New Zealand freshwater ecosystems, and significant culturally, ecologically, economically and recreationally. Substantial habitat loss, urbanisation, and degradation has left longfin eels in a constant state of decline. Although broad guidelines exist for restoring and protecting fish species and general instream habitat conditions, little was known about their effectiveness for protecting longfin eels.
As of 2019, this research project found that there were no specific guidelines for restoring instream urban habitat for the longfin eel in Aotearoa New Zealand. It was therefore concluded that if no action was taken to stabilise and restore longfin eel populations to healthy numbers, the species would likely face extinction. In response, this study provided proposed design guidelines for restoring longfin eel habitat in New Zealand coastal rivers, alongside a first step to restore longfin eel habitat based on the existing conditions of Ōtautahi Christchurch urban rivers. The design guidelines focused on five key determinants of longfin eel habitat quality: river geometry, fish passage, riparian cover, substrata, and water quantity and quality. Due to each urban river in Aotearoa having a unique context and characteristics, it was concluded that further research within this field should focus on identifying specific barriers and enablers of being able to implement the design guidelines presented in this thesis.