A new study published in the Proceedings of the Royal Society B: Biological Sciences reveals that zoos and aquariums have made remarkable advances in animal welfare over the last two centuries, resulting in longer and more equal lifespans for four marine mammal species: the harbor seal, the California sea lion, the polar bear, and the common bottlenose dolphin.
The study also shows that these species live longer in human care than in the wild, where they face threats such as pollution, climate change, hunting, and predation.
A century of progress in animal care
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The study, led by Species360 and University of Southern Denmark Research Scientist Dr. Morgane Tidière in collaboration with 41 co-authors from academic, governmental, and zoological institutions around the world, is the first to examine life expectancy and lifespan equality together as a proxy of population welfare in marine mammal species.
The study used data from the Species360 Zoological Information Management System (ZIMS), which contains records of more than 22 million animals from over 1,200 zoos and aquariums in 99 countries.
The study analyzed 200 years' worth of data from ZIMS, dating as far back as the early 1800s up until 2020.
The study found that the life expectancy of the four marine mammal species has increased by over three times and that the rate of deaths in the first year of life has declined by up to 31% over the last century in zoos and aquariums included in the study.
Additionally, the life expectancy of these species in zoos and aquariums is currently two to three times longer than their counterparts in the wild.
The study also looked at how many of these animals are living well by examining lifespan equality, which can show if a population is consistently living longer lives and avoiding less predictable, earlier causes of death.
The study found conclusively that the four species have progressively increasing lifespan equality across time in zoological institutions.
The authors of the study attribute these impressive results to the significant improvements in animal care and management practices at zoos and aquariums over time.
These include implementing advanced veterinary, environmental, nutritional, and enrichment measures, as well as the voluntary cooperation of animals in routine examinations through positive reinforcement training.
Dr. Tidière said that these findings demonstrate that zoos and aquariums are not only providing high-quality care for their animals but also contributing to their conservation and education.
Zoos and aquariums play a vital role in protecting endangered species and raising awareness about the threats they face in the wild.
By ensuring that their animals live longer and better lives, they also provide valuable opportunities for scientific research and public engagement.
Dr. Dalia Conde, Director of Science at Species360 and Associate Professor at the
University of Southern Denmark, said that this study is an example of how data can be used to measure and improve animal welfare.
"By sharing data on their animals through ZIMS, zoos and aquariums are creating a global resource that can help us understand how animals live and thrive in human care. This can help us identify best practices and areas for improvement, as well as inform conservation actions for wild populations," she said.
The study also highlights some of the challenges and limitations that zoos and aquariums face in caring for marine mammals, such as space constraints, genetic diversity, disease outbreaks, and ethical concerns.
The authors suggest that further research is needed to address these issues and to evaluate the welfare of other marine mammal species and taxa.
