GIS-based multi-criteria analysis of breeding habitats for recolonising species: New Zealand sea lions

Abstract

The New Zealand sea lion (Phocarctos hookeri) is a threatened endemic species, with only three breeding colonies in the sub-Antarctic islands. Since 1993, there has been evidence for recolonisation of mainland New Zealand. Yet the coast that the sea lion has returned to only has fragmented and unevenly distributed potential habitats due to coastal urbanisation and development. Therefore, the need to identify and protect potential breeding habitats for recolonisation is a priority for management.A GIS-based multi-criteria analysis was used to identify potential suitable habitats for a 1600 km length of the NZ South Island coast based on distance to anthropogenic disturbance (urban areas, roads), distance to desirable environmental features (beaches, estuaries) and presence of suitable habitat/land access. From this model, we identified preliminary suitable habitat for breeding sites on the Otago Peninsula (east coast) and Catlins Coast (south). We independently detected some of the current dominant areas used by recolonising sea lions as well as identifying some promising new sites.We discuss the limitation of the results of this case study and the need for further data to be added to the model in the face of limited data availability. Overcoming this data limitation will meet an increasing need for a New Zealand-wide study for determining potential habitat for NZ sea lions. The results of such a study would identify areas to allow real-world management (protection or restoration) of the limited potential breeding sites for New Zealand sea lions. This new method could also be used for other recolonising species and encourage management of areas most likely to be recolonized by them.