DOI: 10.5061/dryad.c6v3838
title: Data from: Simulating nutrient release from parental carcasses increases the growth, biomass and genetic diversity of juvenile Atlantic salmon

description: 1. The net transport of nutrients by migratory fish from oceans to inland
 spawning areas has decreased due to population declines and migration
 barriers. Restoration of nutrients to increasingly oligotrophic upland
 streams (that were historically salmon spawning areas) have shown
 short-term benefits for juvenile salmon, but the longer-term consequences
 are little known. 2. Here we simulated the deposition of a small number of
 adult Atlantic salmon Salmo salar carcasses at the end of the spawning
 period in five Scottish upland streams (‘high parental nutrient’
 treatment), while leaving five reference streams without carcasses (‘low
 parental nutrient’ treatment). All streams received exactly the same
 number of salmon eggs (n = 3,000) drawn in equal number from the same 30
 wild-origin families, thereby controlling for initial egg density and
 genetic composition. We then monitored the resulting juvenile salmon and
 their macroinvertebrate prey, repeating the carcass addition treatment in
 the next spawning season. 3. Macroinvertebrate biomass and abundance were
 five times higher in the high parental nutrient streams, even one year
 after the carcass addition, and led to faster growth of juvenile salmon
 over the next 2 years (but with no change in population density). This
 faster growth led to more fish exceeding the size threshold that would
 trigger emigration to sea at 2 rather than 3 years of age. There was also
 higher genetic diversity among surviving salmon in high parental nutrient
 streams; genotyping showed that these effects were not due to immigration
 but to differential survival. 4. Synthesis and applications: This 2 year
 field experiment shows that adding nutrients that simulate the presence of
 small numbers of adult salmon carcasses can have long-term effects on the
 growth rate of juvenile salmon, likely increasing the number that will
 migrate to sea early and also increasing their genetic diversity. However,
 the feasibility of adding nutrients to spawning streams as a management
 tool to boost salmon populations will depend on whether the benefits at
 this stage are maintained over the entire life cycle.03-May-2019
description: Macroinvertebrate
 biomass and abundanceData corresponding to
 the analyses of macroinvertebrate abundance (individuals min-1) and
 biomass (mg dry mass min-1) when focal fish were age 0+ (May-June 2016)
 and age 1+ (March 2017) in streams with low (0) and high (1) parental
 nutrient levels. Please see Table S1 in Supplementary Information for
 further details of each stream.Salmon focal cohort -
 density and biomass (age 0+ & 1+)Data corresponding to
 the analyses of density (individuals m-2) and biomass (g m-2) of juvenile
 Atlantic salmon (focal cohort) captured at age 0+ (July 2016) and age 1+
 (July 2017) in streams with low (0) and high (1) parental nutrient levels.
 Please see Supplementary Information for further details of each
 stream.Salmon focal cohort -
 fork length & body mass (age 0+)Data corresponding to
 the analyses of fork length (mm) and body mass (g) of juvenile Atlantic
 salmon (focal cohort) at age 0+ in streams with low (0) and high (1)
 parental nutrient levels. Please see Supplementary Information for further
 details of each stream.Salmon focal cohort -
 fork length & body mass (age 1+)Data corresponding to
 the analyses of fork length (mm) and body mass (g) of juvenile Atlantic
 salmon (focal cohort) at age 1+ in streams with low (0) and high (1)
 parental nutrient levels. Please see Supplementary Information for further
 details of each stream.Salmon focal cohort -
 fork length & body mass (age 2+)Data corresponding to
 the analyses of fork length (mm) and body mass (g) of juvenile Atlantic
 salmon (focal cohort) at age 2+ in streams with low (0) and high (1)
 parental nutrient levels. Please see Supplementary Information for further
 details of each stream.Salmon focal cohort - fork
 length & body mass (age
 2).xlsxSalmon second cohort -
 density and biomass (age 0+)Data corresponding to
 the analyses of density (individuals m-2) and biomass (g m-2) of juvenile
 Atlantic salmon (second cohort) at age 0+ in streams with low (0) and high
 (1) parental nutrient levels. Please see Supplementary Information for
 further details of each stream.Salmon second cohort -
 fork length (age 0+)Data corresponding to
 the analysis of fork length (mm) of juvenile Atlantic salmon (second
 cohort) at age 0+ in streams with low (0) and high (1) parental nutrient
 levels. Please see Supplementary Information for further details of each
 stream.