DOI: 10.5061/dryad.9w0vt4bqm
title: Body size and early marine conditions drive changes in Chinook salmon productivity across northern latitude ecosystems

description: Disentangling the influences of climate change from other stressors
 affecting the population dynamics of aquatic species is particularly
 pressing for northern latitude ecosystems, where climate driven warming is
 occurring faster than the global average. Chinook salmon (Oncorhynchus
 tshawytscha) in the Yukon-Kuskokwim (YK) region occupy the northern extent
 of their species’ range and are experiencing prolonged declines in
 abundance resulting in fisheries closures and impacts to the wellbeing of
 Indigenous people and local communities. These declines have been
 associated with physical (e.g., temperature, streamflow) and biological
 (e.g., body size, competition) conditions, but uncertainty remains about
 the relative influence of these drivers on productivity across populations
 and how salmon-environment relationships vary across watersheds. To fill
 these knowledge gaps we estimated the effects of marine and freshwater
 environmental indicators, body size, and indices of competition, on the
 productivity (adult returns-per-spawner) of 26 Chinook salmon populations
 in the YK region using a Bayesian hierarchical stock-recruitment model.
 Across most populations, productivity declined with smaller spawner body
 size and sea surface temperatures that were colder in the winter and
 warmer in the summer during the first year at sea. Decreased productivity
 was also associated with above average fall maximum daily streamflow,
 increased sea ice cover prior to juvenile outmigration, and abundance of
 marine competitors, but the strength of these effects varied among
 populations. Maximum daily stream temperature during spawning migration
 had a nonlinear relationship with productivity with reduced productivity
 in years when temperatures exceeded thresholds in mainstem rivers. These
 results demonstrate for the first time that well-documented declines in
 body size of YK Chinook salmon were associated with declining population
 productivity, while taking climate into account.
description: This is a collated dataset of various freshwater indices for
 Feddern et al. "Body size and early marine conditions drive changes
 in Chinook salmon productivity across northern latitude ecosystems".
 The authors of this dataset were not the original collectors of these
 data, but instead collated them from publicly available datasets, reports,
 and published papers. They are archived here for reproducibility and the
 original sources should be acknowledged. We are very grateful to the
 people who originally collected these data and developed the associated
 models and run reconstructions. The data were collected from: 
 <em><strong>Freshwater
 Covariates</strong></em> Temperature data
 derived from Daymet: https://daymet.ornl.gov/ accessed 2022-11-26 Streamflow derived from GloFAS: https://essd.copernicus.org/articles/12/2043/2020/  via https://doi.org/10.24381/cds.a4fdd6b9 accessed 2022-11-26 Complete code can be found at: doi.org/10.5281/zenodo.13696302
description: # Body size and early marine conditions drive changes in Chinook salmon
 productivity across northern latitude ecosystems
 [https://doi.org/10.5061/dryad.9w0vt4bqm](https://doi.org/10.5061/dryad.9w0vt4bqm) ## Description of the data and file structure This repository contains indices of environmental conditions evaluated for their effect on Chinook salmon productivity.  ### Files and variables #### File: FreshwaterIndices\_Feddernetal.csv **Description:** Indices of freshwater conditions hypothesized to impact Chinook salmon productivity throughout their lifecycle. Watershed specific indices were developed for 26 Chinook salmon populations across the Yukon-Kuskokwim region from DAYMET and GloFAS models. ##### Variables * Population: River for which the index was derived associated with a specific Chinook salmon spawning population * Region: Subregion for which each Population is located * year: Calendar year associated with the index * max5dprcp_spawn: Maximum 5-day precipitation from August - November associated with spawning/incubation lifestage; unit = cm * mnprcp_rear: Median daily precipitation from May - September associated with the juvenile rearing lifestage; unit = cm * maxq_spawn: Maximum daily streamflow from August - November associated with egg incubation; unit = m^3/s * medq_rear: Median daily streamflow from May - September associated with juvenile rearing; unit = m^3/s * mean_swe: Mean snowpack in April represented by snow-water equivalent associated with juvenile rearing; unit  = cm * cdd_rear: Cumulative degree days (base temperature 0 degree C) from May - September associated with juvenile rearing; unit = degree day * maxDaily_spawn: Maximum daily stream temperature from August - November during spawning/incubation; unit = degree C * maxDaily_migrate: Maximum daily stream temperature from July - August during spawning migration; unite = degree C * maxWeekly_migrate: Maximum weekly stream temperature from July - August during spawning migration.daysGT17_migrate; unit = degree C * cddGT17_migrate: Cumulative degree days (base temperature 17 degree C) from July - August during spawning migration; unit = degree day