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Simulated trapping and trawling exert similar selection on fish morphology

Citation

Thambithurai, Davide et al. (2023), Simulated trapping and trawling exert similar selection on fish morphology, Dryad, Dataset, https://doi.org/10.5061/dryad.pk0p2ngq2

Abstract

Commercial fishery harvest can influence the evolution of wild fish populations. Our knowledge of selection on morphology is however limited, with most previous studies focusing on body size, age and maturation. Within species, variation in morphology can influence locomotor ability, possibly making some individuals more vulnerable to capture by fishing gears. Additionally, selection on morphology has the potential to influence other foraging, behavioural, and life-history related traits. Here we carried out simulated fishing using two types of gears: a trawl (active gear) and trap (a passive gear), to assess morphological trait-based selection in relation to capture vulnerability. Using geometric morphometrics, we assessed differences in shape between high and low vulnerability fish, showing that high vulnerability individuals display shallower body shapes regardless of gear type. For trawling, low vulnerability fish displayed morphological characteristics that may be associated with higher burst-swimming, including a larger caudal region and narrower head, similar to evolutionary responses seen in fish populations responding to natural predation. Taken together, these results suggest that divergent selection can lead to phenotypic differences in harvested fish populations.

Methods

This is a grouped dataset created in the R programming language. Data should be used in conjunction with an R script which is found as supplementary materials in the associated article. The dataset will is used to recreate the statistical analyses presented in the article.

Usage Notes

File structure:

file name: gdf.all - global dataset of all fish

coords: procrustes shapes for each fish
Csize: centroid size for each fish
treat: factor indicating what group fish belonged to (high vulnerability or low vulnerability)
gear: gear of each fish
sex: sex of each fish
mass: mass of each fish
length: length of each fish

file name: gdf.tra and gdf.trw - Similar to gdf.all but subsetted for each gear

file name: trap.list and trawl.list - Contain raw morphological coordinates for fish 

fish: raw morphological coordinates taken from fish
length: factor indicating what group fish belonged to (high vulnerability or low vulnerability)

file name: fin.df = data used for caudal area and caudal aspect ratio models

caudal_height: caudal height for each fish in mm
caudal_area: caudal area for each fish in mm sq
gear: gear of each fish
treatment: factor indicating what group fish belonged to (high vulnerability or low vulnerability)
tag.id: elastomer tag code for each fish
w.weight: mass of each fish in grams
sl.length: standard length of each fish in mm
sex: sex of each fish

Below are the packages and versions used to reproduce analysis.

R version 4.1.2 (2021-11-01)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 19042)

Matrix products: default

locale:
[1] LC_COLLATE=English_United Kingdom.1252  LC_CTYPE=English_United Kingdom.1252
[3] LC_MONETARY=English_United Kingdom.1252 LC_NUMERIC=C
[5] LC_TIME=English_United Kingdom.1252

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

other attached packages:
 [1] bootStepAIC_1.2-0 smatr_3.4-8       MASS_7.3-54       caret_6.0-90      lattice_0.20-45   geomorph_4.0.1
 [7] Matrix_1.3-4      rgl_0.108.3       RRPP_1.1.2        forcats_0.5.1     stringr_1.4.0     dplyr_1.0.7
[13] purrr_0.3.4       readr_2.0.2       tidyr_1.1.4       tibble_3.1.5      ggplot2_3.3.5     tidyverse_1.3.1

Funding

European Research Council, Award: 640004

NERC, Award: NE/J019100/1