10.5061/DRYAD.BK3J9KDC9
Cordoleani, Flora
University of California, Santa Cruz
Phillis, Corey
Metropolitan Water District of Southern California
Sturrock, Anna
University of Essex
FitzGerald, Alyssa
University of California, Santa Cruz
Whitman, George
University of California, Davis
Malkassian, Anthony
Aix-Marseille University
Weber, Peter
Lawrence Livermore National Laboratory
Johnson, Rachel
National Oceanic and Atmospheric Administration
Threatened salmon rely on a rare life history strategy in a warming landscape
Dryad
dataset
2021
FOS: Biological sciences
California Sea Grant
https://ror.org/02yn1nr06
82550-447552
United States Bureau of Reclamation
https://ror.org/00ezrrm21
R12PG20200
NOAA Investigations in Fisheries Ecology*
NA150AR4320071
Metropolitan Water District*
California Department of Fish and Wildlife
https://ror.org/02v6w2r95
National Oceanic and Atmospheric Administration
https://ror.org/02z5nhe81
2021-10-14T00:00:00Z
2021-10-14T00:00:00Z
en
https://www.researchgate.net/publication/355034580_Threatened_salmon_rely_on_a_rare_life_history_strategy_in_a_warming_landscape
29007683 bytes
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CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Rare phenotypes and behaviours within a population are often overlooked,
yet they may serve a heightened role for species imperilled by rapid
warming. In threatened spring-run Chinook salmon spawning at the southern
edge of the species range, we show late-migrating juveniles are critical
to cohort success in years characterized by droughts and ocean heatwaves.
Late migrants rely on cool river temperatures over summer, increasingly
rare due to the combined effects of warming and impassable dams. Despite
the dominance of late migrants, other strategies played an important role
in many years. Our results suggest that further loss of phenotypic
diversity will have critical impacts on population persistence in a
warming climate. Predicted thermally suitable river conditions for late
migrants will shrink rapidly in the future and will be largely relegated
above impassable dams. Reconnecting diverse habitat mosaics to support
phenotypic diversity will be integral to the long-term persistence of this
species.
These datasets comprise the part of the manuscript that defines thermally
suitable habitat in a warming climate. Temperature strongly influences
salmonid physiology, growth and survival. Thus populations with access to
diverse water temperatures during incubation and natal rearing are
predicted to exhibit increased phenotypic and phenological diversity. To
support late migrants, stream temperatures need to remain suitably cool
over the summer to accommodate the extended rearing period. Mill and Deer
Creek watersheds, along with upstream reaches of the Battle and Clear
Creeks and the Yuba River, are among the few accessible and populated
spring-run streams in the system that still support all three phenotypes.
To explore why Deer and Mill Creeks may exhibit multiple juvenile life
histories and how life history expression may change with climate change,
we compared current and future thermal conditions along every current and
historical spring-run stream. Temperature was obtained from a mean monthly
stream temperature model. In brief, FitzGerald et al. (2021) employed a
spatial stream temperature model to predict mean monthly stream
temperature for nearly every river km in the western U.S. In the Central
Valley, the test sample r2 was 0.813 and the mean absolute prediction
error (MAPE) was 1.024°C. We first clipped this stream temperature dataset
with the current and historical Central Valley spring-run distributions,
and defined accessible reaches as those downstream of impassable barriers,
such as dams. In general, the distribution and stream networks matched,
but a few reaches with spring-run did not have stream temperature. We
averaged the monthly temperature at each stream segment from 2005-2015,
representing our study period. In the Central Valley, stream temperatures
are predicted to increase by 0.6°C by 2040 and 1.0°C by 2080 (Isaak et al.
2017), so we applied these deltas to the temperature dataset. We then
examined stream temperature suitability (i.e, < 15°C) for juveniles
rearing in May and August of 2005-2015, 2040, and 2080. Here we used a
fixed temperature threshold of 15°C because temperatures greater than
~15°C result in decreased growth rates and increased mortality rates, yet
we acknowledge that there is likely some variation in this threshold
according to local water quality, food availability, and the life stage
considered.
Attached are two shapefiles for data reproduction. The shapefiles
are Central Valley spring-run Chinook salmon spatial distributions (1:
current and historical distributions; 2: accessible distribution) merged
with monthly stream temperature. We include the months (May and August)
and years of interest from our paper (2005-2015 averaged, 2040, 2080). We
also include other months for the above year categories (June, July,
September, October, November) and each individual year from 1993-2015 for
other research. For our paper, we applied a threshold of 15°C, but we
include all temperatures in these files for other research. See associated
README_CVSCStemps file.