Age-at-maturity (AAM) is a key life history trait that provides insight into ecology, evolution, and population dynamics. However, maturity data can be costly to collect or may not be available. Life history theory suggests that growth is biphasic for many organisms, with a change-point in growth occurring at maturity. If so, then it should be possible to use a biphasic growth model to estimate AAM from growth data. To test this prediction, we used the Lester biphasic growth model in a likelihood profiling framework to estimate AAM from length-at-age data. We fit our model to simulated growth trajectories to determine minimum data requirements (in terms of sample size, precision in length-at-age, and the cost to somatic growth of maturity) for accurate AAM estimates. We then applied our method to a large walleye Sander vitreus data set and show that our AAM estimates are in close agreement with conventional estimates when our model fits well. Finally, we highlight the potential of our method by applying it to length-at-age data for a variety of ectotherms. Our method shows promise as a tool for estimating AAM and other life history traits from contemporary and historical samples.
LMLP_fitting_code_Honsey_et_al_Ecol_Apps
This file contains example R code for estimating age-at-maturity and other life history parameters from length-at-age using a Lester biphasic growth model. The model is fit using a profile likelihood approach. This code corresponds with the Ecological Applications article by Honsey et al. entitled "Accurate estimates of age-at-maturity from the growth trajectories of fishes and other ectotherms".
LMLP_simulations_Honsey_et_al_Ecol_Apps
This file contains example code for running simulations to determine the data quality requirements and estimate reliability of the LMLP algorithm as described in the Ecological Applications article by Honsey et al. entitled "Accurate estimates of age-at-maturity from the growth trajectories of fishes and other ectotherms". In this file, growth parameters and sample sizes-at-age are loosely based on walleye Sander vitreus (age-at-maturity = 5 yrs, immature growth intercept = 100 mm, immature growth slope = 50 mm/yr). See Honsey et al. (main text and supplemental file) for details.
Haddock_data_Honsey_et_al_Ecol_Apps
These data describe haddock (Melanogrammus aeglefinus) age (yr), length (cm), sex, and maturity during spring 2015 in the Gulf of Maine. These data were collected as part of the National Oceanic and Atmospheric Administration's Northeast Fisheries Science Center’s bottom trawl surveys (data provided by Mike Palmer, NOAA).
Salamander_data_Honsey_et_al_Ecol_Apps
These data describe age (yr), snout vent length (mm), and maturity of seal salamanders (Desmognathus monticola) collected from Wolf Creek, North Carolina, USA during 1994-1995. These data were provided by Dr. Richard Bruce, Professor Emeritus, Western Carolina University.
Skate_data_Honsey_et_al_Ecol_Apps
These data describe the sex, age (yr), total length (cm), and maturity of Alaska skate (Bathyraja parmifera) taken from the eastern Bering Sea from 2003-2005. These data were collected by the National Oceanic and Atmospheric Administration's Fisheries groundfish trawl surveys (2003-2004) and by the North Pacific Groundfish Observer Program on flatfish trawlers and Pacific cod longline vessels (2004-2005). These data were provided by Beth Matta (NOAA).
MN_Walleye_data_Honsey_et_al_Ecol_Apps
These data describe age (yrs), total length (mm), sex (see Metadata tab), and maturity (see Metadata tab) of walleye collected in a variety of Minnesota water bodies from 1993-2011. The data also include information on water body name (with a unique ID for each water body) and sampling gear type. These data are copyright 2016, Minnesota Department of Natural Resources.
