DOI: 10.7302/z2t151wj
title: Spatially-explicit model code and outputs of Bighead and Silver carp growth rate potential in Lake Michigan

description: Percent Weight Change Data:

The model was run continuously on a daily time step for seasonal intervals (Spring: March thru May; Summer: June thru August; Fall: September thru November) as well as contiguously from Spring to Fall to assess total growth over the likely growing season (March thru November). CSV files represent the simulated weight change (%) of Bighead and Silver Carp for the respective time periods associated with the file name. Initial fish mass for each seasonal interval and growing season was 4350 g for Silver Carp and 5480 g for Bighead Carp. Maximum and mean total weight change (%) was determined for three depth ranges (near surface depths [NS]: 0 – 10 m; deep chlorophyll layer depths [DCL]: 10 - 50 m; and whole water column [WC]). Coordinates are in decimal degrees. 

File naming convention: speciesSeasonWtChange (e.g. bigheadFallWtChange = % weight change of Bighead Carp from September through November)

;
Monthly Habitat Quality Data:

Rdata files contain matrices of Bighead or Silver carp growth rate potential as represented as a mass-proportional growth rate (gram of carp/gram of carp/day [g/g/d]) for the 15th day of each month. Habitats with growth rate potential >= 0 g/g/d were deemed suitable.

Matrix attributes:
Rows: Row numbers refer to the spatial node with 20 equally-spaced vertical layers.
Columns: Columns 1-20 refer to the growth rate potential value for each vertical layer of each node. Vertical layers are evenly spaced based on the total depth of the water column for each node. Depth for each node can be found in the grid attributes data file. Columns 21 ("meanG") and 22 ("Gmax") represent the average and maximum growth rate potential, respectively, of the fish across the whole water column for the corresponding node.

File naming convention: species_MonthNumber (e.g. silver_06 = Silver carp growth rate potential in June)

Spatial coordinates for each node can be found in the grid attributes data files.;
Grid attributes data:

This Rdata file provides the spatial reference data and other grid attributes. Coordinates are provided in UTM (x & y) and latitude and longitude (decimal degrees). Depth (meters) for each node is listed in this file.

;GRP Model code:

Details bioenergetics equations, foraging equation, functions for running the model on a monthly time-step and daily time step, and functions for basic analyses. Model is coded in R.;
The simulated input data (prey and temperature) used to run our model is not included in this data set. Instead we provide the model code, grid attributes, and outputs of the model.

The readRDS() function (R Base Package v.3.5.1) is required to read in .Rdata files in R.

description: We developed a spatially-explicit model that quantifies the growth rate potential (GRP) of non-reproducing adult Bighead Carp and adult Silver Carp (collectively bigheaded carp) throughout Lake Michigan. The GRP model provides a quantitative metric for evaluating habitat quality and suitability by translating prey concentrations at a given water temperature into terms of fish biomass production as indexed by individual growth. Suitable habitat is defined as areas in the lake capable of supporting non-negative growth (indicative that the fish is at least maintaining weight). We applied foraging and bioenergetic equations to outputs of prey (phytoplankton, zooplankton, and detritus) and water temperature simulated by a three-dimensional biophysical model of Lake Michigan. Simulated input data (prey and temperature) are representative of lake conditions in 2010. We ran the GRP model on a monthly time step to characterize the spatiotemporal dynamics of bigheaded carp habitat throughout the year. We also ran the model on a daily time step to determine the total weight change each fish would experience over different periods of the year. The GRP model was coded and ran in R.