Monitoring The Welfare Of Decapods And Cephalopods

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After Brexit, animals in the U.K. lost the protection offered to them under E.U. legislation. As a response, the U.K. government proposed an “Animal Welfare (Sentience) Bill” which initially recognized only non-human vertebrates as sentient. Extensive evidence gathered by researchers convinced the government to include decapods and cephalopods in the Bill. This recognition requires any new government policy in the U.K. to consider the welfare of these individuals during their development.

The use of decapods (e.g., crabs and lobsters) and cephalopods (e.g., octopuses and cuttlefishes) by humans for food, experimentation, and education has risen in recent years. In fact, companies are considering building octopus farms to meet this increasing demand. Increased human use of these animals means that there will be more of them in captivity. With the bill recognizing decapods and cephalopods as sentient beings, the authors of this study make an attempt to monitor their welfare in captivity. 

At the time of the study, there were official methods to monitor invertebrate welfare. To fill this gap, the authors adapted a monitoring tool previously used with mammals and birds called the Animal Welfare Assessment Grid (AWAG). The researchers measured 21 welfare factors in the adapted tool, encompassing each animal’s physical, psychological, environmental, and procedural welfare. Afterwards, they used it in a zoo and an aquarium in the United Kingdom. 

Over the span of 86 days, trained participants observed 112 individual invertebrates, including 108 red-clawed crayfish, one shore crab, a squat-lobster, a male cuttlefish, and a female common octopus. Subjects were scored either daily or three times each week for the duration of the trial.

The observers measured each animal’s physical parameters (e.g., general condition, activity level, food intake), psychological parameters (e.g., abnormal behavior, response to social disruption), environmental parameters (e.g., water quality, group size), and procedural parameters (e.g., impact of veterinary procedures, change in daily routine). The scores were summarized and used to determine the welfare of study subjects, both individually and as groups. This allowed the researchers to track whether certain events reduced or increased the welfare scores. 

The results suggest how decapod and cephalopod welfare can be improved. For instance, the welfare scores of the red-clawed crayfish changed as a response to fluctuations in water quality. The animals swam to the shallows or left the water altogether when the water quality was low. These behaviors are similar to what red-clawed crayfish do in their natural habitat when faced with poor water quality. According to the authors, these findings suggest that AWAG can even be used in the wild to monitor welfare. If the preferred water quality range for red-clawed crayfish is known, then monitoring their behaviors could tell us something about the water quality without having to actually measure it. If the red-clawed crayfish are scoring low on the AWAG, then this may indicate poor water quality. 

Researchers also found that some animals in the study were being kept in less-than-ideal environments, leading to reduced welfare scores. For instance, the shore crab in the study lived in two different tanks: one on-show display tank and another off-show holding tank. The holding tank was less complex than what a shore crab would be exposed to in the wild. According to the authors, this is a common phenomenon for animals kept in zoos and aquaria. Being kept in an environment that is less complex than their natural habitat, the shore crab won’t be able to display certain natural behaviors. The authors suggest that increasing an enclosure’s complexity — for example, ensuring that the animals have more to interact with inside their tanks — can positively influence welfare. 

Other welfare factors are highly species-dependent. For example, red-clawed crayfishes tend to compete over resources, so it’s important to ensure enough resources are provided for all individuals in an enclosure. Meanwhile, octopuses seem to benefit from increased human interactions, and squat lobsters may require a consistent environment with minimal changes.

In addition to pointing out how invertebrate welfare can be improved, a major contribution of this study is to show that their welfare can be monitored in the first place. Since these individuals are increasingly being kept in captivity, it’s very important to find ways of objectively measuring their welfare.

Until decapods and cephalopods are no longer kept in captivity, we must account for the welfare of the ones living in zoos, aquaria, farms, and other human-managed settings. This study presents an adapted tool that can objectively monitor an extensive list of physical, psychological, environmental, and procedural parameters. The results show that the AWAG monitoring tool produces actionable insights for improving the lives of many invertebrates. The authors of this study urge researchers to continue developing and testing tools to monitor invertebrate welfare.