Assessing Wild Octopus Welfare
Identifying signs of welfare threats in wild animals is crucial to understanding how they experience the world and how our actions impact them. While it is easy (albeit potentially unethical) to test different welfare indicators on captive animals, it’s harder to study animals living in the wild. It’s also unclear whether wild and captive animals show the same welfare indicators.
In this study, the researchers evaluated 175 photos and 23 videos of octopuses in the wild taken between 2005 and 2023 to explore potential negative welfare indicators. They analyzed the content to make note of the animals’ body patterns, types and numbers of injuries, irregular chromatophore expression (i.e., changing of body coloration and pattern), and abnormal body positions. They also assessed the context of the photos and videos to understand what situations may present welfare threats to wild octopuses.
The authors found that seven different contexts could potentially impact wild octopus welfare: (1) interacting with fishermen (in the act of fishing); (2) aggressive or combative interactions with other octopuses; (3) interacting with fish; (4) being close or physically interacting with a predator; (5) being inside a sheltered crevice; (6) moving in the water or along substrate looking for food, also known as foraging; and (7) entering a state of senescence (deterioration that occurs near the end of an octopus’s lifespan).
They confirmed six negative welfare indicators that were previously observed in captive octopuses and identified two potentially new measures unique to wild octopuses. The six existing signs of negative welfare include:
- Skin injuries: In captive settings, some skin injuries have been largely attributed to octopuses “jetting” against tank walls. In the wild, interactions with fishermen and predators and agonistic interactions with other octopuses have the potential to cause injuries. In this sampling, injuries were seen most often in interactions with fishermen and when octopuses were in their dens — presumably recovering or protecting themselves.
- Arm loss: Arm loss is common in octopuses, especially through predation. This can impact everyday behavior and mating success and has been used for welfare assessment in captive octopuses. The loss of three or more arms often leads to euthanasia.
- Irregular chromatophore expression: This was observed in 50% of the interactions between octopuses and fishermen. The authors note that handling octopuses roughly can damage their chromatophores. Octopuses with defective chromatophores in the wild are probably at a higher risk of predation due to impaired camouflage.
- Extended papillae expression: The authors claim that wild octopuses normally expose their papillae for short periods, and those with excessive expression in captivity are usually in an excited state. They observed a wild octopus that expressed their papillae for more than one minute. Although more research is required, this is likely another indicator of poor welfare.
- Excess dermal mucus: One of the octopuses displayed a buildup of mucus on the skin, potentially a sign of bacterial growth. Normally, an octopus removes excess dermal mucus via grooming, and previous studies have found that a lack of grooming is linked to other poor signs of health.
- Abnormal body positions: Many octopuses seen interacting with fishermen struggled with body coordination. The authors note that during fishing, octopuses can get hurt by gear and are sometimes discarded or used as bait. These discarded octopuses often exhibit unusual movements, which could indicate discomfort or pain. Impaired coordination hinders basic behaviors like grooming and potentially leads to skin parasites. In the lab, such abnormal behavior is often a sign of imminent death.
The two potentially new welfare indicators unique to wild octopuses are:
- Half-and-half blotch body pattern: This occurs when octopuses have two distinct patterns on either side of their body (one with white spots on a brown background and the other brown and mottled). Other cephalopods, like cuttlefish, also display uneven body patterns when stressed. The authors claim this is the first time such a pattern has been observed in wild octopuses when they’re suddenly approached or touched by a fish. More research is needed to confirm if the “half-and-half” blotch pattern is a common stress response in all octopuses.
- Half-white eye flash: In the past, octopuses have shown a white eye flash around their pupils when faced with approaching predators, possibly as a way to confuse them. One juvenile octopus seen away from their den displayed a white flash, but only on the lower part of the eye, in response to an approaching snorkeler. This octopus also had missing arms and a mantle injury. However, the authors weren’t sure if this response was due to acute stress or if the animal’s injuries prevented the full eye flash.
While the information is insightful, there are some limitations to the study. For example, because the authors relied on photos and videos captured in the wild, they were unable to differentiate all animals by sex and age. Furthermore, the octopuses they looked at may have been affected by the presence of human photographers. Finally, their sample was limited to high-quality photos and videos that were available in the database.
This study shows how minimally invasive assessments of animal welfare can deliver important insights. As advocates continue to speak out against the harm of killing octopuses for food, these indicators may provide a way to evaluate the welfare of wild octopuses subjected to fishing and aquaculture. Finally, the authors believe that their insights may help assess wild invertebrate welfare more broadly.
https://doi.org/10.3390/ani13193021