An exploration of the relationships between environmental drivers and fauna in the Sub-Antarctic

Abstract

Fishery managers in New Zealand are responsible for managing fish stocks and mitigating the effects of fishing on non-target species. Part of this responsibility is to consider how a changing climate impacts the productivity of fisheries. A change in fishery productivity not only affects economic activities related to fishing, but also the species which rely on these fish for survival. If the link between the environment and fishery productivity is not understood and considered in management decisions, then there is a potential for poor outcomes from both the fishing industry and the broader marine ecosystem. Without knowledge of how productivity in ecosystems respond to environmental changes, it is difficult to plan for the effects of a changing climate. Therefore, it is in the interest of fishery managers to clearly understand link between environmental drivers fishery productivity. This research aims to identify which environmental drivers may be influencing productivity and survivorship of certain species in the New Zealand Sub-Antarctic exclusive economic zone. This begins by preparing the data for analysis, which requires and extensive consideration of why values are missing and how to impute them. After imputation, change-point analysis finds locations in the univariate time series where distributional changes occur. Then dynamic factor analysis identifies latent trends common to multiple species and fits environmental drivers to determine which are useful explanatory variables for the dynamic factor models. The results of the change-point analysis provides a few potential relationships between environmental drivers and the fauna. However, the analysis results in no definite conclusions. The dynamic factor analysis indicates that wind patterns may affect recruitment for hake, hoki and southern blue whiting. The analysis also identifies two latent trends which describe general changes in southern arrow squid, scampi, northern royal albatross, Gibson’s albatross and New Zealand sea lion productivity and survivorship in the Sub-Antarctic.