Insights from assessing the welfare of captive dolphins

Author: Dr Isabella Clegg, Animal welfare consultant at Animal Welfare Expertise
Since its inception, animal welfare science has continuously led to improvements in captive animal welfare and helped to clarify our legislation and ethical standpoints around the issues. The spread of welfare science from farms and laboratories to zoos has led to an exponential increase in welfare research on one of the most debated animal groups currently in captivity: dolphins.
There are around 2000 registered captive cetaceans around the world – predominantly dolphins (including killer whales) and belugas – and the number of facilities in places like China is rapidly increasing. This blog outlines the insights gained from dolphin welfare research so far.
Early research
In the years prior to around 2000, much research was carried out on captive dolphins on topics linked to welfare, but the term or principles were rarely considered. For example, stress hormones were studied (Thomson et al. 1986) and stress-related behaviours were described (e.g. stereotypic behaviour, Gygax 1993), but no welfare indicators were identified. Zoo animal welfare had only just started to be studied, and dolphin facilities were often slightly removed from zoos through their different functions and regulation, as well as public perception.
Initial welfare studies
By this point, conditions for captive dolphins in modern facilities were much improved from the last decades, the animals were living as long as their wild counterparts (Jaakkola & Willis 2019) and wild capture was no longer needed because of breeding successes. However, the industry started to face increasing pressure from activists and the public, fuelled by the media and ongoing unacceptable practices in less developed areas. This stimulated the captive facilities to engage with scientists and investigate the dolphins’ welfare more objectively, and from 2010 there was an exponential increase in studies asking questions about dolphin welfare.
Delfour & Beyer (2012) outlined how environmental enrichment should be applied to increase welfare, and Ugaz et al. (2013) found dolphins’ cortisol levels and likely welfare was higher in artificial pools as opposed to sea pens. 
Regular monitoring, especially of behaviour, is crucial to measuring and improving welfare. Photo credit: Beluga Whale Sanctuary
Farm animal welfare techniques were also applied to dolphins, such as the application by Clegg et al. (2015) of the well-established WelfareQuality® framework (2009a,b,c) to dolphins, proposing the first comprehensive welfare framework, called the C-Well©, for these animals. As for other animals, behavioural measures were found to be particularly relevant to overall dolphin welfare, especially since dolphins as prey species often mask symptoms of poor health.
Validating welfare indicators
As welfare studies on captive dolphins continued increasing, it became possible to start validating indicators by correlating multiple parameters. Two studies looked at how the environmental factor of noisy construction work impacts welfare: one study found that play behaviour decreased (Serres & Delfour 2017), and another found cortisol levels increased in response to the stressor (Monreal-Pawlowsky et al. 2017). Anticipatory behaviour (activity performed in preparation for an predictable upcoming event) has started to be investigated in terrestrial animals as a potential welfare indicator, and is proving to be a meaningful measure in captive dolphins, whose daily environments involves many predictable events. Anticipatory behaviour for positive events in dolphins manifests as behaviour such as ‘surface-looking’ and ‘spy-hopping’ (Jensen et al. 2013), and was used to understand the animals’ preference for different events. In a recent study, dolphins’ increased anticipatory behaviour suggested that they ‘looked forward’ to non-food interactions with familiar trainers, and more than toy enrichment (Clegg et al. 2018). These results highlight a few significant measures for dolphin welfare: whether the trainers offer interactions with the animals outside of food provision sessions, and whether the animals show affiliative behaviours towards them, indicating positive human-animal bonds (similarly important to terrestrial animal welfare).
Optimistic dolphins?
A dolphin touches a target as part of a cognitive bias test, an approach which has been valuable in identifying potential welfare indicators. Photo credit: Parc Astérix
One welfare test making waves in terrestrial animal research is investigating ‘cognitive bias’, which basically reveals whether animals make more optimistic or pessimistic judgements in uncertain situations (Mendl et al. 2009). Interestingly, animals that tend to judge optimistically are generally in better welfare, while those who are more pessimistic tend to be in poorer welfare.
With my co-authors, I tested cognitive bias in dolphins, and found that the most optimistic dolphins were those who conducted more affiliative behaviour, measured by the time spent swimming in synchrony. This suggests that providing the opportunity for positive social bonds is a key factor for good welfare in captive dolphins. I did a TEDx talk on the findings of this experiment and how it might even help us understand our own welfare! This is accessible here:
Welfare in the wild
Although there are different definitions, it is now generally accepted that welfare describes how an animal feels. It can therefore exist and apply to animals in the wild too. This can be beneficial for some conservation projects, since individual welfare data can sometimes be more meaningful for real-time threats than population-level parameters, and it also allows the public to empathise and connect with the issues (Beausoleil et al. 2019). Zoos have an important role in this new application of welfare science, as they are currently the only context where welfare research is conducted on wild animal species. Many of the welfare indicators developed so far for captive dolphins can be applied or adapted to their wild counterparts, such as measuring synchronous swimming behaviour, cortisol levels, rake mark coverage and body condition (Clegg et al. 2017).
The welfare of wild animals can also be measured, and can improve our conservation efforts in certain contexts. Photo credit: Patagonia Projects
Research on dolphin welfare has advanced significantly in the last few years, and is helping to improve the conditions for the animals as well as the quality of the debates around their existence in captivity. The dolphins’ welfare is just one aspect of the discussion, and needs to be combined with other equally important elements such as the purposes of keeping them for public display. Studies have started to identify the first indicators of dolphin welfare, such as cortisol levels, synchronous swimming, play, anticipatory behaviour, stereotypical behaviour, and positive human-animal bonds. Cognitive bias testing is a very useful tool for identifying dolphin welfare indicators, as it has been for other zoo and farm animals. More work is needed on the welfare indicators and their inter-individual variability, which will only come from captive facilities continuing to open their doors to researchers, coupled with a societal consensus to optimise the welfare of the animals already under our care.

Links and more info

Twitter: @izziclegg
Instagram: @thedolphindoctor
Animal Welfare Expertise, a consultancy helping to apply welfare science where it is most needed.
TEDx talk: Animals can teach us how to be happier: by being adaptable optimists
More info on animal optimists and pessimists:


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