Abstract
Fishing gears are designed to exploit the natural behaviors of fish, and the concern that fishing may cause evolution of behavioral traits has been receiving increasing attention. The first intuitive expectation is that fishing causes evolution toward reduced boldness because it selectively removes actively foraging individuals due to their higher encounter rate and vulnerability to typical gear. However, life‐history theory predicts that fishing, through shortened life span, favors accelerated life histories, potentially leading to increased foraging and its frequent correlate, boldness. Additionally, individuals with accelerated life histories mature younger and at a smaller size and therefore spend more of their life at a smaller size where mortality is higher. This life‐history evolution may prohibit increases in risk‐taking behavior and boldness, thus selecting for reduced risk‐taking and boldness. Here, we aim to clarify which of these three selective patterns ends up being dominant. We study how behavior‐selective fishing affects the optimal behavioral and life‐history traits using a state‐dependent dynamic programming model. Different gear types were modeled as being selective for foraging or hiding/resting individuals along a continuous axis, including unselective fishing. Compared with unselective harvesting, gears targeting hiding/resting individuals led toward evolution of increased foraging rates and elevated natural mortality rate, while targeting foraging individuals led to evolution of decreased foraging rates and lower natural mortality rate. Interestingly, changes were predicted for traits difficult to observe in the wild (natural mortality and behavior) whereas the more regularly observed traits (length‐at‐age, age at maturity, and reproductive investment) showed only little sensitivity to the behavioral selectivity.
Highlights
Even though most food production is taking place under controlled conditions in farms, fishing is one exception where we rely on wild populations reproducing in their natural habitat, we exploit them with industrialized technology and efficiency
Expectation ↑: Boldness will evolve to higher values because increased mortality favors early reproduction and accelerated life histories
The authors interpreted the model as predicting reduced boldness, that is, inducing a timidity syndrome (Arlinghaus et al, 2017)
Summary
Even though most food production is taking place under controlled conditions in farms, fishing is one exception where we rely on wild populations reproducing in their natural habitat, we exploit them with industrialized technology and efficiency. The traits of wild fish are still subjected to natural selection and may in addition evolve in new directions as they experience selective pressures from fishing and other human activities (Law & Grey, 1989). Identifying these selective drivers and understanding their. Individuals more willing to inspect novel objects will tend to take risks in other settings and move around more These correlation structures have been termed “animal personalities” or “behavioral syndromes” (Sih et al, 2004; Wilson et al, 1994). Boldness is not a single trait, but rather a label ascribed by experimenters and modelers to typically co-occurring behavioral traits
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