@misc{9239493,
  abstract     = {{The role of diversity for the stability of ecosystems is a field traditionally focused on species diversity, rather than diversity within species. This study concerns the latter by investigating the spatial and temporal synchrony and abundance trends within the metapopulation of anadromous sea trout ([i]Salmo trutta[/i]) in Scania, Sweden, that are brought up in different nursey streams but share the same marine environment as adults. Synchrony between subpopulations is the driving mechanism behind the portfolio effect, which states that if the temporal variation in subpopulation abundance is asynchronous, the variation of the aggregate (metapopulation) is more stable than the average subpopulation. This has implications for management since it characterizes the vulnerability of the metapopulation to regional disturbances such as climate change. 
Using simple linear regressions, the mean abundance trends of trout based on annual electrofishing monitoring for 11 streams were investigated to look for patterns within and across streams. The results showed significant negative abundance trends in 4 streams and a positive trend in 1 stream. Pairwise Spearman correlations were then used to quantify the synchrony between time series of mean abundance of sea trout between 2010–2025. To test if geographic distance explained synchrony, linear regressions with euclidean distance and coastal distance between river mouths were used as dependent variables and Spearman (ρ) as independent variables. Synchrony was found to be variable, but on average indicated an absence of synchrony in the region, which could not be explained with distance between streams. The findings indicate the presence of a portfolio effect in the region and that subpopulations have unique dynamics within streams, creating a buffering effect against large scale disturbances such as climate change. However, trends in the region show a decline in sea trout abundance in several streams, indicating a need for management efforts.}},
  author       = {{Norstedt, Kasper}},
  language     = {{swe}},
  note         = {{Student Paper}},
  title        = {{Avsaknad av synkroni inom havsöring (Salmo trutta): En dataanalys av Skånes metapopulation}},
  year         = {{2026}},
}