Data from: Long-term tracking captures the timing of ontogenetic niche shifts in Northeast Pacific white sharks
Data files
Sep 25, 2024 version files 21.78 MB
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Logan_et_al_HighRes_VPS_df.csv
19.17 MB
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Logan_et_al_JWS_PresenceAbsence_df.csv
2.61 MB
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README.md
3.42 KB
Abstract
Ontogenetic changes in area use, habitat use, and trophic interactions play an important role in the ecology, demography, and ultimately population dynamics of many species. Assumed to be driven by shifting life-history requirements, trophic niche shifts in white sharks (Carcharodon carcharias) are well documented, but the timing of the spatial niche shift that is hypothesized to occur with the trophic niche shift remains poorly understood. To document how fine-scale area use varies as sharks age and the timing of the ontogenetic spatial shift of this top predator, we tracked individual white sharks tagged as young-of-the-year or young juveniles over multiple years. Using data from juvenile white sharks detected over multiple years in a nursery habitat with a high-density receiver array, we found no difference in area use with age. However, using a coast-wide receiver array including nursery and adult habitat, we found the probability of detecting a juvenile white shark in nursery habitat decreased with age, with a concurrent increasing probability of detection in adult habitat. As the conservation and management of this species relies on understanding nursery habitat use and age-related movements, data presented here address an important knowledge gap for the understudied juvenile to sub-adult life stages and the ontogenetic habitat shift of this species.
Description of the data and file structure
In “Logan et al_JWS_PresenceAbsence_df.csv”
Date - Date (mm/dd/YYYY)
Shark - Unique identifier for each shark of the dataset, unique for each individual
Dect - binary variable for if a the shark was detected on a given day. 0 = not detected, 1 = detected. Can be detected anywhere on the array.
NumDect - Number of detections recorded during that day for that individual. If detected over multiple regions in a day, the region where the most detections occur is reported (mode of detection regions).
Age - Estimated age of the individual (years). Calculated from the total length of the shark at tagging (to assign age at tagging using von Bertallanffy growth curve parameters) plus the number of days passed since tagging. See text for additional detail.
Sex - Sex of the shark determined at time of tagging.
TagMethod - The method used for tagging the individual shark. See text for more details.
Region - Region where the detection(s) occurred for the given date. If detected over multiple regions in a day, the region where the most detections occur is reported (mode of detection regions). If NA, no detection occurred for the given day.
Length - Estimated length of the individual (cm) based on the size at tagging and the number of days since tagging using von Bertallanffy growth curve parameters. See text.
In “Logan et al_HighRes_VPS_df.csv”, each row holds information about 1 individual dive
DateTimeUTC - date and time of a rendered VPS position in UTC format (mm/dd/yyyy hh:mm:ss)
shark - Unique identifier for each shark of the dataset, unique for each individual
Transmitter - Transmitter ID for each individual shark
lat - latitude of the rendered VPS position in decimal degrees
lon - longitude of the rendered VPS position in decimal degrees
HPE - Horizontal Positional Error of the rendered VPS position (unitless measure). Provided by Innovasea upon data rendering.
sex - sex of the shark determined during tagging.
TNL_cm - Total natural length (cm) of the shark determined during tagging.
X - transformed coordinate for latitude in Mercator projection (meters) EPSG 3857
Y - transformed coordinate for latitude in Mercator projection (meters) EPSG 3857
age - Estimated age of the individual (years). Calculated from the total length of the shark at tagging (to assign age at tagging using von Bertallanffy growth curve parameters) plus the number of days passed since tagging. See text for additional detail.
daily_length - Estimated total length (cm) of the individual based on the size at tagging and the number of days since tagging using von Bertallanffy growth curve parameters. See text.
sizeclass - categorical variable for binning the size (cm; total length) of each shark for each detection day. Bins include 100-200, 200-250, 250-300, 300-350, 350-400, 400+
ageclass - categorical variable for binning the age (years) of each shark for each detection day. Bins include YOY (young of the year), 1, 2, 3, 4, 5, 6, 7, 8, 9.
dailyres - Daily residency index to the VPS array. Calculated as the number of hours detected in the VPS array divided by 24.
Sharing/Access information
please email the lead author, Ryan Logan, rklogn@gmail.com with any questions or for additional information/data.