Do Northern Pike Increase Excruciating Deaths? Implications for Slaughter for Human Consumption

The northern pike (Esox lucius) is a piscivorous fish native to Eurasia and northern North America, which happens to digest their prey while they’re still alive. Assuming being digested alive by a northern pike is an excruciating experience, a single northern pike will probably cause multiple excruciating deaths per week.

An interesting caveat is that a large proportion of the northern pike’s prey is made up of predatory fishes (such as yellow perch), so there’s a chance that they offset the excruciating deaths that they cause by killing other predators. The purpose of this exercise is to determine whether northern pike increase or decrease excruciating deaths overall.

Assumptions

I will assume that the only individuals capable of experiencing excruciating pain are vertebrates and coleoid cephalopods. While there is a nontrivial chance this is incorrect, I suspect that it is the most likely scenario.

Although dying via starvation is also painful, I suspect it isn’t excruciating to the same degree that being digested alive is, so this exercise will focus on deaths from predation. If a predation event on a fish occurs, this prevents the fish from dying in a non excruciating manner (starvation), thus increasing excruciating deaths.

I’m also going to assume that the mortality from all predation is compensatory (unless the study I’m citing suggests otherwise), strictly for the sake of making my calculations easier because I don’t feel like modelling the population dynamics of many fish species.

“Piscivorous” for the purpose of this article refers to consumption of fish post-hatching, not fish eggs. I am assuming that teleost fish are not sentient before hatching, due to vague inferences I made from the larval development of zebrafish. However I suspect there’s a solid (but unlikely) chance this assumption is wrong.

Introduction Into New Environment

First, I will examine the effects of introducing northern pike into new ecosystems. A study that took place in the Experimental Lakes Area of Ontario, Canada involved the introduction of northern pike into 3 lakes that previously had no piscivorous fish. In all 3 lakes, the prey fish (redbelly dace, finescale dace, pearl dace, white sucker, fathead minnow, yellow perch, slimy sculpin) populations were eradicated (Nicholson, 2015). While this definitely was excruciating for the fish that died due to the pike introduction, the alternative is that many of these prey fish species would’ve probably been predated upon by mammals and birds in perpetuity. This pike introduction likely reduced predation events (and other painful deaths) in the long term, thus reducing excruciating deaths.

Existence In Natural Environment

While introducing northern pike into some new ecosystems seems to reduce excruciating deaths in the long term, the result may be different in ecosystems where they’re already established. In order to explore this, I will use a study from Lake Nipissing, that determined the diet composition of northern pike via a stable isotope mixing model. The 7 main fish prey sources were emerald shiner (30%), logperch (27%), yellow perch (~13%), spottail shiner (~10%), rainbow smelt (~8%), juvenile walleye (7%), and trout-perch (~5%) (Johnston, 2021). Since emerald and spottail shiners aren’t piscivorous (Hartman, 1990) and neither are logperch (Stylianides, 2024) or trout-perch (Blouzdis, 2013), the factor that will determine whether northern pike increase or decrease predation events is how often they consume rainbow smelt, walleye, or yellow perch.

I will calculate this by dividing the proportions of the northern pike’s diet by the average masses of each of these prey fish: 3.9g for emerald shiner, 3.6g for logperch, 8.1g for spottail shiner, 7.8g for trout-perch, 19.9g for rainbow smelt, 37.5g for yellow perch, and 44.8g for juvenile walleye (Johnston, 2021). This implies that for every 100g of fish prey consumed by a northern pike, ~7.7 emerald shiners, ~7.5 logperch, ~0.3 yellow perch, ~1.2 spottail shiner, ~0.4 rainbow smelt, ~0.2 juvenile walleye, and ~0.6 trout-perch are consumed. Since the ratio of non-piscivorous fish to piscivorous fish killed by northern pike is so high (~19:1), I will assume that the feeding habits of northern pike in this ecosystem lead to a net increase in excruciating deaths.

Conclusion

It seems to be the case that the presence of northern pike in lakes that recently had no piscivorous fish probably reduces excruciating deaths in the long term, but they probably increase the number of excruciating deaths in lakes that they exist in naturally (at least in Lake Nipissing).

Implications for Slaughter for Human Consumption

From here, we can assume that the slaughter of wild northern pike for human consumption has a solid chance of reducing excruciating deaths due to predation, at least in some lakes where they exist naturally. However, if the practice of slaughtering northern pike increases demand to introduce northern pike into new bodies of water (which has already occured throughout western North America), then it has a solid chance of preventing many excruciating deaths in perpetuity (as in the case of lakes that previously had no piscivorous fish). It also has a solid chance of increasing excruciating deaths, if they are introduced into bodies of water where their behaviour would be similar to that in Lake Nipissing.

Bibliography

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Hartman, K. J., Vondracek, B., Parrish, D. L., & Muth, K. M. (1990). Diets of emerald and spottail shiners and potential interactions with other Western Lake Erie planktivorous fishes. Journal of Great Lakes Research, 16(1), 86–92. https://doi.org/10.1016/S0380-1330(92)71273-8

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Laine, A. (1988). Ecology of a northern pike (Esox lucius) population in a small, oligotrophic lake, with comparisons to other northwestern Ontario populations (Master’s thesis, Lakehead University). https://knowledgecommons.lakeheadu.ca/handle/2453/2141

Mason, D. M., & Brandt, S. B. (1996). Effect of alewife predation on survival of larval yellow perch in an embayment of Lake Ontario. Canadian Journal of Fisheries and Aquatic Sciences, 53(7), 1609–1617. https://doi.org/10.1139/f96-076

Nicholson, M. E., Rennie, M. D., & Mills, K. H. (2015). Apparent extirpation of prey fish communities following the introduction of Northern Pike (Esox lucius). The Canadian Field-Naturalist, 129(2), 165–173. https://www.canadianfieldnaturalist.ca

Schaeffer, J. S., Roseman, E. F., & Riley, S. C. (2014). Development and evaluation of age-structured stock-recruitment models for yellow perch in the Great Lakes. Journal of Great Lakes Research, 40 https://doi.org/10.1016/j.jglr.2014.01.008

Stylianides, A. G., Mueller, S. J., & Stauffer, J. R., Jr. (2024). Diet and Habitat Comparison of Two Closely Related Darters (Percina bimaculata and Percina caprodes). Conservation, 4(4), 594–608. https://doi.org/10.3390/conservation4040036

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