Shark Personalities: A Shark Isn't a Shark Isn't a Shark
Sharks display distinct personalities ranging from worriers to risk takers
Posted May 29, 2016
Individual differences among members of the same species (conspecifics) are well known and we must be very careful when making general -- and misleading -- statements about, for example, "the dog," "the wolf," the raven," or "the goldfish." And, now, we know that sharks, too, display unique individual personalities.
A recent essay called "Some Sharks Worry While Others Take Risks" caught my eye and among the reasons I write these essays is to alert people to what some might call "surprises" in the cognitive and emotional lives of nonhuman animals (animals). And, yes, animals do worry about what's going on around them, and it's essential to come to terms with how individuals deal with different situations (please see "Do Animals Worry and Lose Sleep When They're Troubled?).
It's easy to make over-arching claims about how members of a given species behave and about their personalities. However, these statements, that are not backed by data, are incredibly misleading and don't represent individuals for who they are. In the above essay, that's a summary of a recent research paper titled "Individual personality differences in Port Jackson sharks Heterodontus portusjacksoni" by E. Byrnes and C. Brown, we read "Striking personality differences have just been observed in Port Jackson sharks, which are relatively common sharks in the waters off of southern Australia, including near Port Jackson. The study, published in the Journal of Fish Biology, adds to the growing body of evidence that shark individuals of many, if not all, species are distinct, unique beings just as no two humans are exactly the same." (Other mass media summaries can be found here.)
The research essay is available online so for convenience, here's the abstract:
This study examined interindividual personality differences between Port Jackson sharks Heterodontus portusjacksoni utilizing a standard boldness assay. Additionally, the correlation between differences in individual boldness and stress reactivity was examined, exploring indications of individual coping styles. Heterodontus portusjacksoni demonstrated highly repeatable individual differences in boldness and stress reactivity. Individual boldness scores were highly repeatable across four trials such that individuals that were the fastest to emerge in the first trial were also the fastest to emerge in subsequent trials. Additionally, individuals that were the most reactive to a handling stressor in the first trial were also the most reactive in a second trial. The strong link between boldness and stress response commonly found in teleosts was also evident in this study, providing evidence of proactive-reactive coping styles in H. portusjacksoni. These results demonstrate the presence of individual personality differences in sharks for the first time. Understanding how personality influences variation in elasmobranch behaviour such as prey choice, habitat use and activity levels is critical to better managing these top predators which play important ecological roles in marine ecosystems.
Fishes are a major part of the ongoing humane revolution
Byrnes and Brown point out that personalities have been documented in more than 200 species and I'm sure the number will continue to grow as more research is conducted. Fishes are not mere streams of edible unfeeling protein (please see "Fishes Know, Feel, and Care: A Humane Revolution in Progress" and links therein) and we need to get out of this narrow and abusive mindset.
Please stay tuned for more the fascinating cognitive and emotional lives of the magnificent beings with whom we share our magnificent planet. There's lots more going on beneath the surface in the hearts and heads of a wide variety of species that must be factored in as we try to peacefully coexist with them. Fishes are a very good place to begin to expand our horizon and our compassion footprint. We, and other mammals, surely are not the only members of the sentience club and surely are not the only beings who care about what happens to ourselves, families, and friends (please also see "Insect Brain Capable of Conscious Subjective Experiences"). It's a win-win for all when we recognize all animals for who they truly are.
Marc Bekoff's latest books are Jasper's Story: Saving Moon Bears (with Jill Robinson), Ignoring Nature No More: The Case for Compassionate Conservation, Why Dogs Hump and Bees Get Depressed: The Fascinating Science of Animal Intelligence, Emotions, Friendship, and Conservation, Rewilding Our Hearts: Building Pathways of Compassion and Coexistence, and The Jane Effect: Celebrating Jane Goodall (edited with Dale Peterson). (Homepage: marcbekoff.com; @MarcBekoff)