Carp Personality, by Hanna Moreland

In a study conducted by Klefoth et al. (2012) questioned whether boldness of specific carp increased capture rate through hook and line fishing.  They are not the only investigators studying personality in fish.  In this essay I explore three questions. What is boldness in carp?  How do we measure it? What are the implications of this research?  I will explore these questions in the context of the Klefoth et al. study in order to give a better understanding of why this research is so important.

Common Carp Cyprinus carpio.  Photo from Flickr.  CC BY-NC-ND 2.0

Science would be easier if we could just ask animals their personality traits through a short quiz or verbal interaction. How can a carp have a personality? One way to measure personality in carp is to identify if the individual is bold or not bold. In this study carp boldness was measured by tracking fish movements within a small pond with transmitters. In the pond there were shelters the researchers placed which the carp used for safety. Some carp spent their time mostly in the shelter, some spent some time right outside the shelters, and others ventured far from the shelter. Those individuals who ventured far from the shelter site were considered bold and marked as so for later testing. Do these individuals have a higher production of a hormone or a genetic sequence that makes them more likely to be bold?  Klefoth et al. (2017) indicates that there is a genetic component to being bold as boldness was a repeatable measurement in this experiment as well as in other experiments studying fish.

Next, I’m going to explore why measuring boldness matters in the context of this article as well as in relation to angling. Klefoth et al. (2012) asked whether boldness and catchability were correlated. They hypothesized that the bold individuals, those who ventured far from the shelters in the pond, would be more likely to be caught by anglers because they were in open waters. The research indicates that a correlation exists! Those individuals marked as bold in the first part of the study, were the carp more likely to be caught in the second half of the study. This has great implications for management strategies in both threatened species and species intended for harvest. If boldness is truly genetic and moderately heritable these traits can be selected and bred for. In relation to threatened species, individuals who stay in the shelters would be most useful for breeding purposes because they are more cautious and less vulnerable to predation. On the other hand, for game fish purposes the bold fish would be the focus of breeding and stocking programs. In this study bolder fish were more likely to be caught which means happier anglers if bold fish are stocked in popular carp fishing ponds!

 

Carp breaching.  Photo by Stan Lupo.  CC BY-NC-NC 2.0.  Source.

Of course, there are still a lot of questions that need to be answered before breeding programs can be initiated. Further research can delve into what makes a carp bold, whether it be genetic or hormone related. Next studies could focus on if boldness is heritable from parent to offspring and by what magnitude as traits like length and size are only moderately heritable in fish (Garcia et al. 2007). If these continued research efforts yield positive results this could mean new management techniques that improve populations of threatened and game carp species. Finally, similar research could be conducted on other species of fish to see if the same results hold true and can be applied to their own management programs. Fish may not be as different from humans with regards to personality. This new finding opens new windows of opportunity for bold students willing to explore these implications through further research and management.

References

Garcia de Leaniz, C., and fourteen coauthors. (2007). A critical review of adaptive genetic variation in Atlantic salmon: Implications for conservation. Biological Reviews, 82, 173– 211.

Klefoth, T., Skov, C., Kuparinen, A., & Arlinghaus, R. (2017). Toward a mechanistic understanding of vulnerability to line fishing: Boldness as the basic target of angling‐induced selection. Evolutionary Applications, 10, 994– 1006.

Klefoth, T., Skov, C., Krause, J., & Arlinghaus, R. (2012). The role of ecological context and predation risk‐stimuli in revealing the true picture about the genetic basis of boldness evolution in fish. Behavioral Ecology and Sociobiology, 66, 547– 559. 

-->