Protecting biodiversity across land and sea: opportunities for comparative life cycle assessment metrics. A case study on the impacts of salmon farming.

Abstract

Biodiversity is invaluable to human well-being, yet it is declining at a rate faster than ever in human history, where one major driver is food production. Assessing the biodiversity impacts of foods is therefore critical, but current life cycle assessment methods focus mainly on terrestrial systems, limiting comparisons between agricultural products and seafood. This thesis explores if and how a leading terrestrial biodiversity assessment framework (Scherer et al., 2023) can be adapted for marine environments, and specifically to Norwegian Atlantic salmon farming as a case study. The methodological framework was broken down into eleven components, and ecological considerations for adaptation were explored through a narrative review. Insights on local salmon farm impacts were obtained through a systematic literature review and through analysing publicly available monitoring data. Several important ecological differences between land and sea were highlighted, including lower species richness but higher phylogenetic diversity in marine systems, and generally greater dispersal abilities among marine organisms. The work also identified region-, species-, and activity-specific data needed to enable application of the framework in marine contexts. The case study on Norwegian salmon farming informed six components of the framework, most importantly highlighting spatial aspects of species richness impacts and commonly assessed species groups. Advancing and integrating terrestrial and marine approaches to assess biodiversity impacts can become a powerful future pathway to more sustainable global food production.