DOI: 10.5061/dryad.1vhhmgqvv
title: Alaska Sustainable Salmon Fund Project #52002: Climate warming effects on Chinook Salmon foraging conditions and growth

description: The Chena River hosts one of the largest populations of Chinook Salmon in
 the Alaska portion of the Yukon River drainage, which has recently
 experienced poor Chinook returns throughout. Past work suggests that these
 fish do poorly when they grow slowly due to cold, high-flow conditions
 during their first summer in the river as juveniles, and the population
 does well when juveniles experience warm, low-flow years and grow larger.
 Because high flow drives low water temperatures and vice versa, it was
 previously unclear to what extent each factor—flow and temperature—affects
 the fish population. We collected data to run foraging and bioenergetics
 models that simulate how flow and temperature affect growth. We invented
 two sampling devices, a suction pump to sample drifting prey and a
 computer vision system to measure the inedible debris that occupy most of
 a fish’s feeding effort. We combined our data with USGS and NOAA records
 to predict temperature, turbidity, prey, and debris on a daily basis
 throughout our study years (2019-2020) and others. This dataset contains
 the data we collected and compiled from other sources on fish growth,
 temperature, invertebrate drift, and drifting debris.
description: Temperature data were collected by placing Hobo data loggers at
 our study sites (see Study Site Map.png) for two years. We used a machine
 learning model in Mathematica (gradient-boosted trees) to predict water
 temperature at the USGS Two Rivers hydrograph (data available from USGS
 from late-2013 onward) based on streamflow, day-of-year, and air
 temperature at the Fairbanks airport. We then used that regression,
 streamflow, and air temperature as predictors for machine learning models
 (by the same method) to estimate daily temperature (degrees C) at all of
 our study sites from 1967 to present. Invertebrate
 drift data were collected using a suction pump as described in the
 associated Hydrobiologia publication:  Neuswanger. J.R., Schoen, E.S.,
 Wipfli, M.S., Volk, C.J., and Schoen, E.R. 2022. A suction pump sampler
 for invertebrate drift detects exceptionally high concentrations of small
 invertebrates that drift nets miss. Hydrobiologia (in press). DOI:
 10.1007/s10750-022-04849-1. Juvenile Chinook salmon
 were sampled via dip net and minnow trap at approximately two-week
 intervals throughout the summers of 2019 and 2020. Fork length was
 measured to the nearest mm and mass to the nearest 0.1 g. This produced
 two fairly high-resolution time series of juvenile Chinook Salmon growth,
 which we combined with data from the literature, our own past studies, and
 colleagues' sampling reports to the Alaska Department of Fish and
 Game to produce several additional time series of fish growth.
 Debris data were collected using a Sony mirrorless digital camera
 to photograph a flow-through chamber at two-second intervals, with both
 the camera and powerful LED lights controlled by a Raspberry Pi
 microcomputer. Hundreds of thousands of these debris images were then
 analyzed using a custom algorithm based on the OpenCV library to count and
 measure drifting debris particles fish might mistake for prey. Several
 paragraphs of details about this device can be found in our project's
 final report to the Alaska Sustainable Salmon Fund, and up-to-date Python
 code for the debris counter analysis algorithm is available on Github at
 https://github.com/JasonNeuswanger/DebrisCounterAnalysis.
description: The spreadsheets in "Completed Field Datasheets"
 include all environmental data associated with our collections (e.g.
 turbidity, windspeed) in a consistent format. The date and site name
 listed on those sheets corresponds to a code "YYYY-MM-DD
 SiteName" that was used to reference data collected there in
 subsequent files. Temperatures throughout these files
 are given in degrees C. Drift concentrations and energy contents are given
 in #/m<sup>3</sup> and J/m<sup>3</sup>,
 respectively. Masses are given in grams and fish lengths in mm.
 The "Site Predictions" folder contains observed,
 predicted, and "best" temperature columns for each of our study
 site. The "observed" column usually only includes 1-2 years of
 data. The "best" column uses the observed data when available
 and the predicted data otherwise.