DOI: 10.5061/dryad.hdr7sqvpp
title: An ecosystem sentinel for the northeast Pacific Ocean twilight zone

description: 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.
description: # 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 that produce their first pup. MeanLRS = Cohort-averaged
 lifetime reproductive success (# pups born to each recruited female)
 LowerLRS = Lower credible interval of lifetime reproductive success (#
 pups born to each recruited female) UpperLRS = Upper credible interval of
 lifetime reproductive success (# pups born to each recruited female)
 MassMean = Cohort-averaged mass (kilograms) of weaned female pups born to
 three-year-old moms MassLower = Lower credible interval of mass
 (kilograms) of weaned female pups born to three-year-old moms MassUpper =
 Upper credible interval of mass (kilograms) of weaned female pups born to
 three-year-old moms MassVar = Variance of mass (kilograms) of weaned
 female pups born to three-year-old moms ### GainIndWide *each row is an
 individual seal mom* MassGain = Body mass gained during foraging trip
 (kilograms) YearWhenTracked = Year that seal moms were instrumented momID
 = Unique identifier for seals that were moms ### OceYrWide *each row is a
 year* Year = Year of oceanographic measurements (annual averages) NPGO =
 Annual average of North Pacific Gyre Oscillation index PDO = Annual
 average of Pacific Decadal Oscillation index SOI = Annual average of
 Southern Oscillation Index ### PupMomMassIndWide *each row is a mother-pup
 pair* Weight = Weight of pup measured after weaning from mom (kilograms)
 MassGain = Body mass gained during foraging trip (kilograms) momID =
 Unique identifier for seals that were moms animalID = Unique identifier
 for pups born to individual identified seal moms Please note that
 "NA" in cells mean that no data were observed. ### MarkRecap
 cohort = Cohort number age = Age for survival metric Phi = Survival rate
 from age x to age x+1 years = Year of demographic metric ###
 Lifetime-return Lifetime-return.PDF is an appendix that contains variation
 in lifetime detection probability. ### NESE\_ALL\_DiveStatType\_5 *each
 row is a dive* TOPPID = Individual identifier for each deployment Year =
 Year of the dive JulDate = Julian date of the dive, in MATLAB format
 DiveNumber = Sequential number of each dive for each TOPPID Maxdepth =
 Maximum depth of each dive, in meters DiveTypeName = Name of the dive type
 (Transit, Foraging, etc)