Jumping the Shark

Julian mentioned in passing the other day that he thought it would not obviously be immoral, and perhaps even morally desirable, to eliminate all shark species from the earth. The reasons he gave related to their limited ecological role, the fact that sharks only serve to further deplete the already under-populated reserves of bony fish (especially large pelagics like tuna and mackerel), and the suffering they inflict on other vertebrates (including other fish, aquatic birds and mammals, and higher cognitive mollusks) in the course of feeding. Lamentably (in my view), Julian’s off-the-cuff prescription is currently being fulfilled, if unintentionally: Humans are currently killing sharks at the rate of around 40 million per year (mostly for their fins alone), and since most sharks (unlike bony fish) have small numbers of offspring at a time, these rates of killing are quite likely unsustainable. Here I want to briefly touch upon the moral value of sharks, especially at the level of species.

First, however, I will talk briefly about individual sharks.  Something is morally considerable if it has interests that it would be prima facie wrong to frustrate, where this wrongness stems from the intrinsic value of the being in question and not from any indirect effects it may have on other valuable beings. Individual sharks are morally considerable and thus intrinsically valuable if one takes as the relevant capacity the ability to feel pleasure and pain. There is a fair bit of evidence from behaviour, anatomy, physiology, neurology etc. that fish can feel pain. Although most of this research was carried out, I would hazard a guess, on bony fish (for reasons of practicability), the above properties and their neural-anatomical correlates are almost certainly an ancestral trait present in the common ancestor between bony fish and sharks—so I think it is safe to say that sharks can feel pain and hence should not be made to suffer needlessly. There is no question that the ‘finning’ of sharks does precisely this in a most brutal and torturous way. But let’s pretend that there were entirely pain-free ways of eliminating shark populations, such as by reducing their birth rates to the point that they were exceeded by death rates, causing the species to go extinct. Would this be a bad thing?

If so, it will likely be due to the relational value of sharks, rather than to their intrinsic value as morally considerable beings. Species qua species cannot be said to have intrinsic value, because they quite obviously do not exhibit any of the properties thought to confer moral considerability, such as personhood or sentience, or even the most basic (and inclusive) properties of living things, such as goal directedness. Although the consensus in evolutionary biology is that species are individual lineages evolving in space and time, rather than a-temporal natural kind classes, species are not the sort of individual that is amenable to moral considerability: Unlike individual organisms, species do not exhibit internal homeostatic mechanisms, differentiated parts, a degree of functional autonomy, a developmental life cycle, reproduction, metabolism, and other such traits. Species therefore cannot plausibly be said to have intrinsic value. So this leaves us with a few possible sources of species value. First, species may be of instrumental value to morally considerable beings, perhaps because of the ‘ecological services’ they provide or the cascading effects their extinction would have on a food web. There are hundreds of species of shark, ranging in size from a few centimetres to behemoth plankton feeders, exhibiting highly diverse functional and ecological roles. It is therefore difficult to say anything general about the moral value of shark species per se, as opposed to this particular species of shark in this particular ecological context. Nevertheless, many sharks, especially the large predatory oceanic ones (such as great whites, tigers, makos, blues, etc.) are relatively small in number, in part because they sit atop the food pyramid; as a consequence, they are ecologically insignificant as compared to primary producers and their extinction would have relatively negligible effects on global ecology.

In defending the ecological value of species like apex predatory sharks, people are inclined to appeal to the delicate balance of nature or the unravelling of seamless food webs in the face of minor ecological perturbations, but these metaphors are, to put it mildly, scientifically unsupported (both paleontologically and neontologically) and have no place in serious normative discussions about the value of species. Knowledge of the ecological interactions and energy flow between species enables biologists to predict different harms that are likely to result from the extinction of different lineages. Although sharks are often claimed to cull ‘sick or diseased fish’, there is no shortage of scavengers to do the same job in their absence. Although great white sharks may cause a slight reduction in seal populations in certain areas of the globe, shark predation is surely a minor factor in understanding the large-scale determinants of the demographic structure of these marine mammals. And as mentioned above, there is clearly no overabundance of large pelagic fish—quite the contrary, these risk extinction over the next century due to massive overfishing by humans.

If shark species are valuable, then, this must be for largely non-instrumental reasons. Perhaps then shark species have extrinsic-final value, that is, they are valuable to morally considerable beings in and of themselves and not toward some other end. Objects of historical significance are commonly thought to have extrinsic final value, and the proliferation of UNESCO World Heritage sites and their associated tourism can attest to this. If human history has final value, it is not a stretch to think that natural history might have it as well (indeed, many protected World Heritage sites are in fact ‘natural’ sites, such as mountain ranges, barrier reefs, and fossil deposits). For its part, the shark lineage appeared very early in the history of complex life (some 400-450 million years ago), and has survived every single mass extinction since then. If they were to go extinct, all of the evolutionary information accumulated over hundreds of millions of years would be gone; this information could prove valuable, both for instrumental and extrinsic-final reasons (which are too numerous to mention here). Many divers, snorkelers, marine biologists, ichthyologists, natural historians and the like find sharks extraordinarily fascinating in their own right. I don’t know if these values outweigh other competing interests, such as the ones that Julian mentioned in our brief discussion by the office water cooler. But I do have a deep intuition that a world without sharks would be a worse world in which to live. My initial inclination is to say that there is a certain rate of premature human (and nonhuman animal) death that I am willing to stomach in order to assure the existence of these aesthetically and historically significant creatures, and likewise for large cats, bears, and crocodiles. To be frank, I am not sure entirely where this intuition comes from, or whether it can be systematically defended. Since I was a child I always felt a special connection to marine fauna, and perhaps it is from this untranslatable feeling that my inclination to preserve shark species springs. Nevertheless, there is something wonderfully humbling about sharks and other apex megafauna—something that allows us to relate to and affirm our million-year-old identity as fearful hominid prey. I for one take great comfort in knowing that there are animals out there in the seas and savannahs that would eat me if they had the chance.