10.5061/DRYAD.N560CD7
Beacham, Terry D.
Fisheries and Oceans Canada
Araujo, H. Andres
Fisheries and Oceans Canada
Tucker, Strahan
Fisheries and Oceans Canada
Trudel, Marc
Fisheries and Oceans Canada
Data from: Validity of inferring size-selective mortality and a critical
size limit in Pacific salmon from scale circulus spacing
Dryad
dataset
2019
Pacific Salmon
Oncorhynchus
Size-selective mortality
2019-06-11T00:00:00Z
2019-06-11T00:00:00Z
en
https://doi.org/10.1371/journal.pone.0199418
53266653 bytes
1
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Size-selective mortality owing to lack of energy reserves during the first
marine winter has been suggested to be a result of juvenile salmon failing
to reach a critical size or condition by the end of their first marine
summer and not surviving the following winter due to this presumed energy
deficit. This hypothesis implies a knife-edge mortality function based
upon size, and is subject to empirical data support for acceptance. Scale
circulus spacing has been interpreted as an index for body size, and we
reviewed the effect of size-selective mortality with a knife-edge
mortality function on descriptive statistics for a scale circulus spacing
index (SCSI). In order to invoke size selection as an important driver of
mortality during the first year of ocean rearing, it is necessary to
demonstrate not only that size-selective mortality is directed towards the
smaller members of the population, but that the selective nature of the
mortality can account for a substantial portion of the observed mortality.
If the assumption is made that a random sample of a single juvenile
population has been obtained, then studies that employ a SCSI to infer
size-selective mortality coupled with a critical size limit must
demonstrate a shift toward larger values of the SCSI, but also a
concomitant reduction in the variance and range of the SCSI and an
increase in the skewness and kurtosis of the SCSI values. Through
simulation we found that the percentage of adults that displayed a SCSI
value greater than the maximum observed in the juvenile sample was highly
dependent on the initial juvenile sample size and size-selective mortality
rate. Geographical distributions of juvenile Pacific salmon can be
stratified by size, with larger individuals migrating earlier from local
ocean entry locations than smaller individuals, and thus differential
timing migration of juveniles based upon body size prior to the collection
of the marine juvenile sample may be a more plausible explanation of
published trends in the SCSI, rather than invoking substantial
size-selective mortality and a critical size limit.
Simulated Statistics-Knife Edge MortalityFile:
SimulatedStatistics-KnifeEdgeMortality.csv This file contains the
simulated data from a knife-edge size-selective mortality simulation.
Description of the variables: Juveniles: Sample size for the juvenile
population Adults: Sample size for the adult population Mortality:
Mortality rate (in percent) Mean: Mean circuli spacing of the adult
population Range: Difference between the maximum and minimum circuli
spacing in the adult population Min: Minimum value of the circuli spacing
in the adult population Max: Maximum value of the circuli spacing in the
adult population SD: Standard deviation of the circuli spacing in the
adult population Kurt: Kurtosis of the circuli spacing in the adult
population Skew: Skewness of the circuli spacing in the adult population
Percent: Proportion of the circuli spacing in the adult population that is
outside (above) of the juvenile
populationSimulatedStatistics-KnifeEdgeMortality.csvSimulatedStatistics-TwoSamplesFILE: SimulatedStatistics-TwoSamples.csv This file contains the simulated data from a sampling conducted on two populations. Description of the variables: Mean 1st: Mean circuli spacing in the first population Mean 2nd: Mean circuli spacing in the second population Sample size: Total number of circuli spacing in the sample Prop pop 1: Proportion of the samples coming from the first population Prop pop 2: Proportion of the samples coming from the first population Mean: Mean circuli spacing of the joint sample Range: Difference between the maximum and minimum circuli spacing in the joint sample Min: Minimum value of the circuli spacing in the joint sample Max: Maximum value of the circuli spacing in the joint sample SD: Standard deviation of the circuli spacing in the joint sample Kurt: Kurtosis of the circuli spacing in the joint sample Skew: Skewness of the circuli spacing in the joint sample Percent: Proportion of the circuli spacing in the adult population that is outside (above) of the joint sample
North Pacific