This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Two recent review articles in the journals Trends in Ecology & Evolution and Fish and Fisheries, to which researchers from the Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB) contributed, focus on the influence of humans on the diversity of fish behavior and on how management can help preserve this diversity. Although Amazon mollies are genetically identical as clones of their mothers, individual fish systematically differ from one another in their behavior—even when raised under identical conditions.
This is true even for juvenile fish. In fact, among all fish species studied to date, there is immense variation among individuals, including shy and bold or social and less social individuals. Researchers refer to these as behavioral types.
Fish account for about half of all vertebrate species and exhibit an impressive diversity of behaviors within populations, between populations of the same species and between populations living in different ecosystems. As with all vertebrates, behavioral diversity in fish arises from the interplay of various factors. These include an animal's internal state (e.g., hunger level), its genetic makeup, its ability to flexibly adapt its behavior and the external conditions to which it is exposed.
And this diversity can be systematically altered by humans. Robert Arlinghaus, professor of integrative fisheries management at IGB and Humboldt Universität zu Berlin, has been studying the behavior of freshwater fishes for many years. He contributed to the two articles, which provide an overview of how human activities influence fish behavior and how humans exert a selective pressure that differs from natural factors.
Arlinghaus explained, "Human influences on fish behavior include, for example, habitat alteration and disturbance, migration barriers, pollution, the spread of invasive species, intensive and trait-selective fishing, animals escaped from aquaculture and climate-driven shifts in ecological processes. These so-called anthropogenic factors can directly or indirectly influence activity and movement, reproductive behavior, reactions to predators, aggression, social behavior, cognition and learning." One example of this is the selection of certain behavioral traits caused by fishing. Previous studies by the IGB have shown that, in recreational fishing, it is primarily the bold and active carp and pike that are removed from the populations.
In heavily fished aquatic ecosystems, shyness can therefore be an evolutionary advantage and become established over generations. "However, this also means that fish in heavily fished areas no longer swim around as actively. This can alter the distribution of fish, the relationships between predators and prey, and competitive dynamics," said Arlinghaus.
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