An ecosystem sentinel for the northeast Pacific Ocean twilight zone

Despite holding most of the global fish biomass, the open ocean twilight zone (200-1,000 m) is poorly understood due to the difficulty of measuring subsurface ecosystem processes at scale. We demonstrate that a wide-ranging carnivore - the northern elephant seal - serves as an ecosystem sentinel for the open ocean. We linked ocean-basin-scale foraging success with  oceanographic indices to estimate twilight zone fish abundance five decades into the past, and into the future. We discovered that small variation in seal foraging success amplifies into large demographic changes in offspring body mass, first-year survival, and recruitment. Further, worsening oceanographic conditions could shift predator population trajectories from current growth to sharp declines. As ocean integrators, wide-ranging predators can reveal the impacts of past and future anthropogenic change on open ocean ecosystems., , , # Title of Dataset: A long-lived vertebrate sentinel for open ocean ecosystems

---

Four .csv files contain processed data necessary to reproduce figures and analysis as written in the R code \"Cohort Code Analysis 2024_06_17.r\". Note that NA values indicate a missing measurement (e.g., weanling mass was not measured in a certain year). 

## Description of the Data and file structure

Headers in the .csv files are as follows:

### DemYrWide

*each row is a cohort*

Year = Year of birth for a cohort
FirstYrSurv = Average first year survival (%) for the cohort
FirstYrSurvN = Number of seals from which survival values were calculated
N = Number of seals used to calculate proportion recruited
PropRecruit = The estimated proportion of seals in a cohort that produce their first pup.
PropRecruitLower = Lower credible interval of the estimated proportion of seals in a cohort that produce their first pup.
PropRecruitUpper = Upper credible interval of the estimated proportion of seals in a cohort...