Filters: Tags: migratory fish (X)
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Number of migratory fish species, by freshwater ecoregion. We derived the map of long-distance migrant (LDM) fish—the number of LDM species per ecoregion—from published literature, online databases (NatureServe), and expert inquiries. Potadromous, anadromous, amphidromous, and catadromous fish species were judged to be LDMs if they made regular journeys (i.e., for breeding, dispersal, feeding) of at least a hundred kilometers or more in freshwater. These species were then assigned to ecoregions based on the fish species lists database from Abell et al. (2008). Although we used many resources, two key data sources for the map were the following: Carolsfeld, J., B. Harvey, C. Ross, and A. Baer, eds. 2003. Migratory...
Degree of disruption of fish runs, by freshwater ecoregion. The level of disruption of fish runs was determined by Reidy-Liermann, C. A., C. Nilsson, J. Robertson, and R. Ng (unpublished) by calculating the average proportion of undammed distance among the longest connected freshwater pathways (including lakes) in each ecoregion, regardless of stream order. This metric considered only the five longest water courses or river segments between or without dams. Depending on the confidence in the underlying dam and reservoir data, ecoregions without known dams may have been deemed either as fully free-flowing or as having insufficient data. When dams data were deemed unreliable for a river, those dams were excluded...
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