Can fish feel pain?

By Fiona Graham, RJD Intern

Pain and suffering in fishes has been a hotly debated topic throughout the past, especially in the context of angling. While previous research has stated that fish might indeed feel pain, the authors of this paper decisively contradict these studies. This paper by Rose and colleagues details a comprehensive literature review and analysis of past studies claiming that fish feel pain. Specifically, they focus on deficiencies in the methods used for pain identification, and invalidating claims for consciousness in fishes.

The seven authors of the paper concluded that conscious pain in fishes is highly unlikely. Some fish have certain types of sensory receptors, called nociceptors, which can evoke nocifensive (nociception-evoked) behaviors, such as withdrawal or avoidance. However, while these behaviors can often be mistaken for pain or suffering, it is argued here that these are unconscious reactions used for escape and unconscious learning in order to avoid such situations. These authors emphasize the distinction between nociception, the unconscious sensory detection of harmful stimuli and conscious pain.They note that consciousness is a precondition for experiencing pain and that it is unlikely that consciousness would be adaptive for fishes or neurologically feasible.

Interestingly, elasmobranchs, particularly sharks, appear to be even less responsive to nociception than other fishes. Sharks and rays lack a key region of the spinal dorsal horn responsible in mammals for transmitting nociceptive activity to the brain. Additionally, they lack certain fibers responsible for the intense pain induced suffering in conscious humans.

A student takes a small fin clip sample to help gather data on shark toxicology levels.

The results of this study have implications for human-fish relations that are affected by misconceptions surrounding pain and suffering in fishes. Most notable among these are scientific studies involving fishes, aquaculture and commercial fishing, recreational fishing and fisheries management. In addition, these findings are integral to the accurate understanding of the nature and welfare needs of fishes.

REFERENCE
Rose, JD et. al. (2012) “Can fish really feel pain?” Fish and Fisheries