DOI: 10.5061/dryad.kt136
title: Data from: Tracking restoration of population diversity via the portfolio effect

description: 1. Declines in diversity among populations managed together have
 diminished aggregate stability through a decreased portfolio effect.
 Although the portfolio effect has been quantified in a variety of ways,
 management recommendations for the recovery of lost diversity rarely
 specify the stability benefits possible through such improvements. 2. We
 introduce a metric, the Diversity Deficit (DD), that relates past losses
 and potential gains in aggregate stability to the changes in population
 diversity (i.e., covariability among population time series). We
 illustrate use of this DD in retrospective analyses of the aggregate
 Sacramento River Fall-run Chinook salmon stock (Oncorhynchus tshawytscha),
 and project potential future improvements in stability through population
 diversity. 3. In the retrospective analysis, we removed individual time
 series from the stability calculations to determine their effects on times
 and locations of past losses in diversity and stability. We found an early
 threefold loss in stock stability resulting from the presence of a single
 tributary, the Sacramento River mainstem. Other shifts in stability
 resulted from an increase in variability of a single population, and from
 the synchronizing effects of low ocean survival that led to the 2008-09
 fishery closure. Only one, smaller increase in the DD (i.e., in lost
 stability) was due to portfolio-wide increases in covariabilities among
 tributary abundances. 4. In a prospective analysis using the DD applied to
 California salmon, we found that increasing biodiversity to the point of
 population independence and to its early high value would have reduced the
 probability of triggering a fishery closure. 5. Synthesis and
 applications. Analyses with the DD illustrate a means to identify the
 times and locations of losses in population diversity, and to quantify how
 much restoration of population diversity could increase stability, thus
 benefit resource services. Here the benefit was a reduction in the
 probability of falling below a critical management threshold leading to
 fishery closure, but other tangible benefits (e.g., reduction in
 probability of extinction) would be possible.12-Jun-2017
description: Sacramento River
 Fall-run ProductionThis data set contains
 yearly production values (estimated escapement abundances plus in-river
 and ocean harvests) of Sacramento River Fall-run Chinook salmon for
 1952-2010. The Sacramento River Fall-run Chinook is an aggregate stock
 consisting of five populations associated with different tributaries of
 the Sacramento River: Battle Creek, the Sacramento River mainstem, Feather
 River, Yuba River, and American River. Data were previously available as
 part of the Central Valley ChinookProd data set, maintained by the US Fish
 and Wildlife Service Anadromous Fish Restoration Program
 (https://www.fws.gov/lodi/anadromous_fish_restoration/afrp_index.htm).
 These specific data are no longer available online, but are presented here
 in the format used for analyses in the manuscript. Note that analyzed data
 includes years 1957-2010.Sacramento_Fall_Production_1952_2010.csv