Data from: Long-term changes in the juvenile Sockeye salmon rearing capacity of the Chignik lakes watershed

Freshwater ecosystems respond rapidly to perturbations in climate,
geomorphology, and population abundances. For migratory species in
interconnected habitat networks, local habitat conditions can control the
productivity of individual populations. Asynchronous variation in habitat
quality can simultaneously stabilize ecological processes at broad scales
but also complicate the understanding of ecosystem dynamics. We
investigated habitat-specific trends in indicators of the rearing capacity
for juvenile sockeye salmon in a remote watershed in Alaska over the last
~60 years. The motivation of this effort was to understand if the collapse
of the local salmon fishery in 2018 could be traced to changes in habitat
quality within the nursery watershed. Our analyses describe high
variability in the habitat conditions across both spatial and temporal
scales, yet do not suggest a decline in the overall sockeye salmon rearing
capacity of the watershed. We observed increasing maximum water
temperatures in a shallow lake but more stable conditions in a deep lake,
an improvement in zooplankton prey resources in the deep lake, and
increased juvenile sockeye salmon growth rates throughout the watershed.
Although we detected no long-term decline in rearing habitat quality,
there was a decrease in juvenile sockeye salmon abundance from 2013-2016,
suggesting high early life stage mortality prior to the period of juvenile
rearing leading up to the fishery collapse.