Do risk-prone behaviours compromise reproduction and increase vulnerability of fish aggregations exposed to fishing?

Human disturbances can prompt natural antipredator behaviours in animals,
affecting how energy is traded-off between immediate survival and
reproduction. In our study of male squaretail groupers (Plectropomus
areolatus) in India's Lakshadweep archipelago, we investigated the
impact of fishing pressure on anti-predatory responses and reproductive
behaviours by comparing a fished and unfished spawning aggregation site
and tracking responses over time at the fished site. Using observational
sampling and predator exposure experiments, we analysed fear responses
(flight initiation distance, return time), as well as time spent in
vigilance, courtship, and territorial defence. Unpaired males at fished
sites were twice as likely to flee from simulated predators and took
longer to return to mating territories. Contrastingly, males in the
presence of females at both sites took greater risks during courtship,
fleeing later than unpaired males, but paired males at the unfished site
returned earlier. Our findings suggest that high fishing pressure reduces
reproductive opportunities by increasing vigilance and compromising
territorial defence, potentially affecting mate selection cues. Altered
behavioural trade-offs may mitigate short-term capture risk but endanger
long-term population survival through altered reproductive investment.
Human extractive practices targeting reproductive aggregations can have
disruptive effects beyond direct removal, influencing behaviours crucial
for population survival.