DOI: 10.5061/dryad.qbzkh18sk
title: Data from: Advancing the understanding of spearfisher-fish behavioral interactions and its management implications

description: Fish behavior is intimately linked to fishing catchability. Measurements
 of fish behavior may provide quantitative indicators that inform about the
 impact of fishing pressure and help design effective management
 strategies. The implications of spearfishing pressure on fish behavior
 have been mainly characterized using single quantitative indicators such
 as flight initiation distance (FID), which provide incomplete views of
 spearfisher-fish behavioral interactions. We used an integrative
 approach to advance the understanding of spearfisher-fish behavioral
 interactions by complementing FID estimates with post-flight responses
 (i.e., individual fish behavior after fleeing), and the decreasing
 probability to catch a fish at increasing distance from a speargun. We
 first collected empirical observations of white seabream (Diplodus sargus)
 FID and post-flight behavior in response to an approaching human
 (spearfisher or snorkeler) inside and outside marine protected areas. We
 then combined these observations with simulations based on an innovative
 model representing how catchability changes during a spearfisher-fish
 behavioral interaction. Empirical results showed that the
 likelihood of a still-vulnerable post-flight response after fleeing was
 inversely related to increasing exposure to spearfishers. This
 demonstrates that post-flight response can be used as an indicator of
 spearfishing pressure. Moreover, post-flight responses provided
 complementary information to that provided by FID, suggesting that these
 two indicators should be integrated for a holistic view of
 spearfishing-fish interactions, such as in the model and simulations
 presented here. The simulations demonstrated that: (i)
 accounting for post-flight responses may increase likelihood of approach
 by spearfisher within speargun range by up to 20%; and (ii) accounting for
 post-flight responses and decreasing probability of capture with increased
 distance from speargun drastically reduces estimates of likelihood of
 capture of white seabream at minimum catch length limit outside marine
 protected areas compared with using FID as single indicator of
 catchability. Synthesis and applications: First, integrating FID
 measurement with post-flight responses provides a more realistic indicator
 to measure fish behavioral reaction to spearfishing pressure. Second, the
 model presented here showed that spearfishing mortality may drastically
 decrease when accounting for both prey behavior (i.e., FID and post-flight
 responses) and spearfishers effectiveness (i.e., probability to catch a
 fish at increasing distance from a speargun). This must be considered to
 understand population dynamics and potential changes in catchability when
 spearfishing is managed through temporal restrictions (e.g., seasonal or
 periodic closures).
description: Measurement of flight-initiation distance,
 post-flight behavior and estimated size of the fish were collected during
 underwater observations We measured FID and
 post-flight behavioral response to four treatments: two areas with
 different levels of harvesting protection status (protected/unprotected
 from spearfishing) and two diver configurations (potentially threatening
 spearfishing with a speargun and non-threatening snorkeling without a
 speargun). All observations were conducted at a minimum distance of 750 m
 from the borders of marine protected areas. All sites were surveyed by the
 same operator. The spearfisher was equipped with a speargun (100 cm long,
 slings were removed and substituted with PVC tubes to not violate
 regulations of the MPAs) and with the typical spearfishing equipment
 (black wetsuit, long black fins and black mask). The snorkeler equipment
 consisted of a short blue wetsuit, short blue fins and a colored mask. The
 different diver configurations (spearfisher/snorkeler) were applied inside
 and outside each marine protected area in a random order over 4–7
 consecutive days. Success of
 approach and capture can be obtained by running the model associated with
 the data. The model represents a spearfisher-fish behavioral interaction
 to assess how likelihood of approach and capture a white seabream changed
 when accounting for: <em>(i)</em> FID; <em>(ii)
 </em>post flight behavior; and <em>(iii)</em> the
 decreasing probability to catch a fish at increasing distance from a
 speargun. To create models for <em>(i) </em>and <em>(ii)
 </em>we used the empirical data described above where the observer
 simulated a spearfisher approach both inside and outside marine protected
 areas, while for <em>(iii)</em>, we also interviewed 16
 specialized spearfishers and asked them to estimate the probability
 (0-100%) to successfully catch a medium size <em>D. sargus
 </em>(i.e., 30-35 cm) by shooting with a 100 cm long speargun from
 four distances (2.5; 3.0, 3.5; 4.0 m).
description: # Advancing the understanding of spearfisher-fish behavioral interactions
 and its management implications
 [https://doi.org/10.5061/dryad.qbzkh18sk](https://doi.org/10.5061/dryad.qbzkh18sk) ## Description of the data and file structure * Measurement of flight-initiation distance, post-flight behavior and estimated size of the fish were collected during underwater observations ("pf.behavior.xlsx") * We measured FID and post-flight behavioral response to four treatments: two areas with different levels of harvesting protection status (protected/unprotected from spearfishing) and two diver configurations (potentially threatening spearfishing with a speargun and non-threatening snorkeling without a speargun). All observations were conducted at a minimum distance of 750 m from the borders of marine protected areas. All sites were surveyed by the same operator. The spearfisher was equipped with a speargun (100 cm long, slings were removed and substituted with PVC tubes to not violate regulations of the MPAs) and with the typical spearfishing equipment (black wetsuit, long black fins and black mask). The snorkeler equipment consisted of a short blue wetsuit, short blue fins and a colored mask. The different diver configurations (spearfisher/snorkeler) were applied inside and outside each marine protected area in a random order over 4–7 consecutive days. * Success of approach and capture can be obtained by running the model associated with the data. The model represents a spearfisher-fish behavioral interaction to assess how likelihood of approach and capture a white seabream changed when accounting for: *(i)* FID; *(ii) *post flight behavior; and *(iii)* the decreasing probability to catch a fish at increasing distance from a speargun. To create models for *(i) *and *(ii) *we used the empirical data described above where the observer simulated a spearfisher approach both inside and outside marine protected areas, while for *(iii)*, we also interviewed 16 specialized spearfishers and asked them to estimate the probability (0-100%) to successfully catch a medium size *D. sargus *(i.e., 30-35 cm) by shooting with a 100 cm long speargun from four distances (2.5; 3.0, 3.5; 4.0 m; "catch_estimate_distance.xlsx"). A script for data analysis and running the model is provided along with the data. REGARDING THE DATA FILES: * The empirical data are provided with a well-detailed METADATA sheet. * The R script is provided with detailed annotations. ### Files and variables #### File: catch\_estimate\_distance.csv | Size | Estimated size of the fish | | :--------- | :-------------------------------------------------------------------------------------------------------------------------------------------- | | Area | The area where the observations were coming from (3 levels) | | Prot.hunt | The experimental treatment (NP-H = spearfishing outside MPA; NP-NH = snorkeling outside; P-H = spearfishing inside; P-NH = snorkeling inside) | | Start.dist | Starting distance from where the FID measuremetn started | | ESCAPE | Post Flight behavior (0=approach; 1=slow displacement; 2=moderate flight speed; 3=high flight speed) | | FID | Flight initiation distance | #### File: pf\_behavior.xlsx | distance | The distance between the speargun and the fish to estimate the perceived likelihood of catching it | | :--------- | :-------------------------------------------------------------------------------------------------------------------------------------------------- | | Catch\_L | The probability (0-100%) to successfully catch a medium size D. sargus (i.e., 30-35 cm) by shooting with a 100 cm long speargun from four distances | | Experience | The years since the spearfishers started to practive spearfishing | ## Code/software The R script is appropiately annotated.