You can't go home again: Changes in trophic niche following extinction and recolonization of the New Zealand sea lion

Recolonization or range expansion of large marine predators can be facilitated by reestablishing formally important trophic linkages within intact coastal marine food webs. We analyzed long-term changes in the structure of coastal marine food webs supporting remnant and recolonizing populations of New Zealand sea lions (Phocarctos hookeri), an apex marine predator, using trophic position and a mixture of alternate sources of organic matter as metrics for their resource niche. We measured both d13C, d 15N, and d 15NAA of amino acids in the collagen of archived prehistoric bone samples and modern bone, muscle, and fur samples. Using the resulting isotopic values we calculated individual-based estimates of trophic position and basal organic matter source use from pelagic and benthic habitats, phytoplankton versus macroalgae, in the underlying food webs supporting sea lions from the Auckland Islands, Stewart Island, Southland, and Otago among discrete time periods dating to the fi..., , , # Data from: You can't go home again: Changes in trophic niche following extinction and recolonization of the New Zealand sea lion

[https://doi.org/10.5061/dryad.h9w0vt4tj](https://doi.org/10.5061/dryad.h9w0vt4tj)

## Description of the data and file structure

The data contained in the file \"Dryad Data ECS24-0444 (Wing et al. 2025 Ecosphere).xlsx\" are derived from an extensive isotopic study of bone collagen from prehistoric, historic, and modern samples from the New Zealand sea lion (*Phocarctos hookeri*).  The data represent samples from three geographic regions (subantarctic islands, central New Zealand, and the mainland South Island of New Zealand) across three distinct periods early Maori, middle European expansion, and modern industrialised periods, representing the complete history of human occupation in New Zealand.

Samples from bone material were used to isolate collagen and then both bulk (d13C, d15N) as well as compound-specific analysis of d15N in amino acids was carried ...