Data from: 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 first human settlements in New Zealand. The data
resolved significant changes in the trophic position of New Zealand sea
lions since the first arrivals of Māori in New Zealand (ca 1250-1450 CE),
the advent of European whaling and sealing (ca 1650 -1850 CE) when sea
lions were extirpated from the South Island, and expansion of
industrialized fishing (ca 1950 -present CE) indicating a vastly altered
resource landscape for recolonizing populations on the South Island. New
Zealand is the last major land mass to be settled by people therefore the
patterns we observe comprise the complete time course of human influences
on the marine ecosystem. These patterns provide a unique understanding of
how long-term changes in coastal marine food webs influence the trophic
position and population recovery of apex predators.