DOI: 10.5061/dryad.m0cfxppbg
title: Data and code from: Recreational fisheries selectively capture and harvest large predators

description: Size and species selective harvest, inevitably alters the composition of
 targeted populations and communities. This can potentially harm fish
 stocks, ecosystem functionality, and related services, as evidenced in
 numerous commercial fisheries. The high popularity of rod-and-reel
 recreational fishing, practiced by hundreds of millions globally, raises
 concerns about similar deteriorating effects. Despite its prevalence, the
 species and size selectivity of recreational fisheries remain largely
 unquantified due to a lack of combined catch data and
 fisheries-independent surveys. This study addresses this gap by using
 standardised monitoring data and over 60,000 digital angling catch reports
 from 62 distinct fisheries. The findings demonstrate a pronounced
 selectivity in recreational fisheries, targeting top-predators and large
 individuals. Catch-and-release practices reduced the overall harvest by 60
 % but did not substantially alter this selectivity. The strong species-
 and size-specific selectivity mirror patterns observed in other fisheries,
 emphasising the importance of managing the potential adverse effects of
 recreational fisheries selective mortality and overfishing.
description: Scripts and data files have been utilised to compare trophic
 level, relative species abundance, and size distribution (European perch
 and pikeperch) of angling catches to monitoring data across 62 distinct
 fisheries (lakes) where data overlapped.  The two
 datasets consist of monitoring data from the national database for
 standardised survey fishing with Nordic multi-mesh gillnets (National
 Register of Survey test‐fishing ‐ NORS, 2021) and angling data from catch
 reports submitted to the online fishing license sales platform iFiske AB
 (https://www.ifiske.se/). Detailed information about prior data filtering can be found in the README as well as in the uploaded .R-file together with scripts for all analyses.
description: # Data and code from: Recreational fisheries selectively capture and
 harvest large predators
 [https://doi.org/10.5061/dryad.m0cfxppbg](https://doi.org/10.5061/dryad.m0cfxppbg) In this study we take advantage of an extensive database of more than 200,000 angler catch reports from Swedish recreational inland fisheries and relate it to monitoring (fisheries independent) data on the associated fish communities. To this end, we first compared relative species abundance and the trophic level of angling catches to monitoring data across 62 distinct fisheries (lakes) where data overlapped. Next, we assessed size selectivity of these fisheries on European perch (hereafter perch, *Perca fluviatilis*, Percidae) and pikeperch (*Sander lucioperca*, Percidae), two predatory focal species in the fisheries. Finally, we explored the effects of C&R practices on selectivity by disentangling angler harvest from angler catch (including released fish) in all analyses. The results provide quantitative and robust estimates of species and size selective harvest in recreational fishing with implications for management of stocks targeted by rod-and-reel fisheries. ## Description of the data and file structure The two datasets consist of monitoring data (monitoring_data.csv) from the national database for standardised survey fishing with Nordic multi-mesh gillnets (National Register of Survey test‐fishing ‐ NORS, 2021) as well as angling data (angling_data.csv) from catch reports submitted to the online fishing license sales platform iFiske AB ([https://www.ifiske.se/](https://www.ifiske.se/). Both datasets are fully anonymised and lake names have been substituted with numerical labels. Each row in the datasets represens a reported fish ### Monitoring data * Lake_ID (anonymised numerical label instead of lake name) * Year * SpeciesName * cmklass (standard length in cm) ### Angling data * Lake_ID * Year * SpeciesName * Weight (individual weight in grams derived from either individual or joint reports) * Report (Individual = the row represents a fish reported with an individual weight; Joint = the row represents a fish reported with a joint weight) * Fate (the fate of the individual; either harvested, released, or no answer) ### Prior filtering Monitoring data has been filtered to only include survey fishing performed according to the standard Swedish method for freshwater fish. Angling data have been filtered so that reported catches with passive gears (e.g. gill nets, longlines, and fyke nets) were excluded. Data were restricted to the years 2010-2020. Small Swedish lakes are typically managed jointly with additional waters by a single local organisation, and consequently, catch reports from such waters cannot be linked to specific lakes. Therefore, lakes with an area less than 15,000 m2 was excluded from the initial lake selection (number of lakes in the monitoring dataset was reduced from 842 to 128). Remaining lakes were matched to the angling dataset resulting in 113 lakes where both monitoring and angler catch data were available. Among these, 78 were managed by distinct local management organisations, each covering the entire lake (constituting at least 90 % of the water area). We considered each of these lakes as distinct fisheries. Two adjacent lakes, both having monitoring data from the same years, were managed by a single local organisation and consequently, we merged monitoring data and treated the two lakes as a single Fishery in the analyses. At last, fisheries with fewer than 100 reported angling catches were excluded from the selection to improve the overall quality of catch data, resulting in a total of 62 distinct fisheries included in the analyses. Anglers often caught several individuals of the same species and reported the total mass together with the number of caught individuals of the species-specific catch (~50 % of reports were of combined body mass after excluding zero catch reports). Individual body mass from these reports were calculated as averages. ## Sharing/Access information Data was derived from the following sources: * National Register of Survey test-fishing - NORS. (2021). *Swedish University of Agricultural Sciences, Department of Aquatic Resources*. [http://www.slu.se/sjoprovfiskedatabasen](http://www.slu.se/sjoprovfiskedatabasen) * iFiske AB ([https://www.ifiske.se/](https://www.ifiske.se/)) - Data not publicly available ## Code/Software The R script file (Code for Recreational fisheries selectively capture and harvest large predators.R) consist of all scripts used in our analyses. The scripts were created using version 4.3.1 (2023-06-16). Annotations are provided throughout the script. ### Versions of packages used: * DHARMa 0.4.6 @DHARMa * ggeffects 1.3.1 @ggeffects * ggpubr 0.6.0 @ggpubr * ggsignif 0.6.4 @ggsignif * lme4 1.1.35.1 @lme4 * Matrix 1.6.4 @Matrix * mgcv 1.9.0 @mgcv2003; @mgcv2004; @mgcv2011; @mgcv2016; @mgcv2017 * nlme 3.1.163 @nlme2000; @nlme2023 * rstatix 0.7.2 @rstatix * tidyverse 2.0.0 @tidyverse