Fish populations globally are susceptible to endangerment through exploitation and habitat loss. We present theoretical simulations to explore how reduced adult survival (age truncation) might affect short-lived freshwater fish species in human-altered contemporary environments. Our simulations evaluate two hypothetical "average fish" and five example fish species of age 1 or age 2 maturity. From a population equilibrium baseline representing a natural, unaltered environment we impose systematic reductions in adult survival and quantify how age truncation affects the causes of variation in population growth rate. We estimate the relative contributions to population growth rate arising from simulated temporal variation in age-specific vital rates and population structure. At equilibrium and irrespective of example species, population structure (first adult age class) and survival probability of the first two adult age classes are the most important determinants of population growth. As adult survival decreases, the first reproductive age class becomes increasingly important to variation in population growth. All simulated examples show the same general pattern of change with age truncation as known for exploited, longer-lived fish species in marine and freshwater environments. This implies age truncation is a general potential concern for fish biodiversity across life history strategies and ecosystems. Managers of short-lived, freshwater fishes in contemporary environments often focus on supporting reproduction to ensure population persistence. However, a strong focus on water management to support reproduction may reduce adult survival. Sustainability management needs a focus on mitigating adult mortality in human-altered ecosystems. A watershed spatial extent embracing land and water uses may be necessary to identify and mitigate causes of age truncation in freshwater species. Achieving higher adult survival will require paradigm transformations in society and government about water management priorities.

Data were generated by computer simulation. Details are contained within individual R scripts. Summary data sets of mean contributions for Figs 2 and 3 of Hatch et al. are given individually in subfolders for each example.

This supporting file to Hatch et al. (2020) is a ZIP archive of folders and subfolders containing R scripts (.R) and simulation results (.Rdata) for all simulations reported in the aforementioned publication. The ZIP file contains two parts for simulations of age 1 maturity (a) and simulations for age 2 maturity life histories. Full simulation results are provided for five example species (Enteromius motebensis, Hybognathus amarus, Hybognathis argyritis, Iberochondrostoma lusitanicum, and Pseudobarbus burchelli) and two representations of an "average fish".

Consult R scripts (.R) in each folder.