Carbon and nitrogen isotope data from zooplankton and fish larvae collected on the SR2114 expedition in the Eastern Tropical North Pacific aboard the R/V Sally Ride from December 2021 to January 2022

This dataset includes carbon and nitrogen isotope data from zooplankton and fish larvae collected on the SR2114 expedition onboard the RV Sally Ride from December 2021 to January 2022. Samples were collected using a MOCNESS (Multiple Opening-Closing Net and Environmental Sensing) system. The vertical sampling strategy followed five specific oxypleths (referred to as sampling levels) using horizontal tows. The zooplankton samples were preserved in ethanol 95%. The stable isotope ratios of carbon (13C/12C) and nitrogen (15N/14N) were measured on 39 samples of zooplankton, 44 samples of fish larvae, and 8 samples of fish adults. Carbon and nitrogen isotope ratios were measured at the Boston University Stable Isotope Laboratory using a GV Instruments IsoPrime isotope ratio mass spectrometer coupled with an elemental analyzer. The results were compared to international standards (Pee Dee Belemnite for 13C and atmospheric nitrogen for 15N) and presented as delta notation. This methodology was followed to gather information on the trophic structure of the ecosystem and its ontogenic changes during early fish development.