Abstract
As welfare studies on dolphins under human care continue to increase, it becomes more and more important to find practical indicators that can be used by professional animal care staff during their daily routines. Evaluation of gastric fluid may represent a potential tool for better understanding marine mammal welfare.
We present here the first findings about the use of gastric fluid obtained from clinically healthy Bottlenose dolphins (Tursiops truncatus) as a potential welfare indicator. An approach was developed in which this parameter was assessed in combination with other known welfare indicators, such as faecal cortisol values and behavioural parameters.
This study was carried out in Attica Zoological Park in Greece, which houses the largest Bottlenose dolphin bachelor male group in Europe, nine males housed together as one single group, and Mediterraneo Marine Park in Malta, which houses a small bachelor male group, consisting of two male individuals. All dolphins that participated in this study were conditioned to voluntarily allow for the collection of gastric fluid, thereby ensuring a relatively non-invasive procedure to obtain the samples. Gastric fluid samples were taken before the first meal of the day, at least sixteen hours after the last feeding activity of the previous day and before the first fish reinforcement of the sampling day. We implemented a method in which physiological parameters, as well as behavioural observations and qualitative assessments were combined in different settings and contexts.
Association between the animals, environmental enrichment, Willingness to Participate1,2, nature of activities during the day, and behavioural diversity3,4 were seen to correlate withto changes in gastric fluid samples. Qualitative evaluation carried out by the dolphin carers confirmed these findings.
We strongly believe that our findings are the first step towards the development of a new indicator for dolphin welfare evaluation, that will provide a vast array of information and at the same time will be easily applicable in the different dolphinaria around the world.
Literature Cited
1. Clegg, I.L.K.; Rödel, H.G.; Mercera, B.; van der Heul, S.; Schrijvers, T.; de Laender, P.; Gojceta, R.; Zimmitti, M.; Verhoeven, E.; Burger, J.; et al. Dolphins’ willingness to participate (WtP) in positive reinforcement training as a potential welfare indicator, where WtP predicts early changes in health status. Front. Psychol. 2019, 10, 2112.
2. Delfour, F.; Monreal-Pawlowsky, T.; Vaicekauskaite, R.; Pilenga, C.; Garcia-Parraga, D.; Rödel, H.G.; García Caro, N.; Perlado Campos, E.; Mercera, B. Dolphin Welfare Assessment under Professional Care: “Willingness to Participate”, an Indicator Significantly Associated with Six Potential “Alerting Factors”. J. Zool. Bot. Gard. 2020, 1, 4.
3. Miller, L.J.; Vicino, G.A.; Sheftel, J.; Lauderdale, L.K. Behavioral diversity as a potential indicator of positive animal welfare. Animals 2020, 10, 1211.
4. Delfour, F.; Vaicekauskaite, R.; García-Párraga, D.; Pilenga, C.; Serres, A.; Brasseur, I.; Pascaud, A.; Perlado-Campos, E.; SánchezContreras, G.J.; Baumgartner, K.; Monreal-Pawlowsky, T. Behavioural Diversity Study in Bottlenose Dolphin (Tursiops truncatus) Groups and Its Implications for Welfare Assessments. Animals 2021, 11, 1715. https://doi.org/10.3390/ani11061715