May 31, 2016 — As seen in other animal species, fish individuals tend to react differently to a new situation. In the case of human harvest, the boldest individuals are more likely to get caught, leaving only the fearful and cautious ones to breed. But does it mean that future generations of fish will become harder to catch? This is one of the questions the BE-FISH project tried to answer.
Fish personality—consistent individual behaviour which is maintained over time and across contexts—is known to result from adaptive processes involving life-history trade-offs or physiological constraints. Concretely, a population from a single species can include individuals of the same sex, size or age which feature different behavioural traits, these traits being grouped in five major categories: shyness-boldness, exploration-avoidance, activity, sociability and aggressiveness. Various studies have demonstrated that this personality variation is heritable.
Scientists in the BE-FISH (Pace of life syndromes in fish: harvesting effects and the role of marine reserves) project have long suspected that fisheries may contribute to such evolutionary impacts in marine resources by selectively removing specific life-history traits.
Dr David Villegas-Rios, Marie Curie Postdoctoral fellow at the Flødevigen Research Station (IMR) and coordinator of the project, discusses the project results. According to him, they provide a unique link between fisheries, behavioural ecology and evolutionary biology sciences, and as such will lead the way to various national and EU projects in the coming years.
Human harvesting is a non-random activity. It often removes individuals because they are more desirable (e.g. trophy hunting) or because they are more vulnerable, as is the case for fishing. For instance, bolder individuals will enter a fishing trap more easily than shier ones. Similarly, more active fish find the nets faster than less active individuals. This means that behaviour can determine fitness.
By consistently removing individuals with certain behavioural properties, fishing practices can entail evolutionary consequences in the harvested populations. For instance, by favouring evolution towards less active phenotypes. The ecological consequences of such practices are still largely unknown but they can be maladaptive, reducing the potential for future adaptations along with the productivity of the populations.