Data from: Advancing the understanding of spearfisher-fish behavioral interactions and its management implications

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).