My Green Job: Reproductive Scientist at the Toronto Zoo

Toronto Zoo’s senior director of wildlife science, Gabriela Mastromonaco, is the only reproductive scientist working at a zoo in Canada. She helps create the next generation of genetically diverse animals to live in zoos and for release into the wild.

Mastromonaco’s motto is: “If you don’t have reproduction, you don’t have species survival.” Not content to use current reproductive approaches, she wants to push the field forward  — and has 110 scientific publications to prove it. For her innovative approach to animal reproduction and biodiversity, she’s been nominated for the Indianapolis Prize, which is so prestigious it’s been dubbed the Nobel for animal conservation.

Diane Peters: How did you get into this career?

Gabriela Mastromonaco: I started in human reproduction and I was going to help make more humans. But then I realized it wasn’t where I wanted to be. After doing an undergraduate and then a master’s in microbiology at the University of Toronto, I worked at the Toronto Zoo as a research assistant for four years. Animal reproduction and specifically wildlife reproduction became my passion. I did my PhD in reproductive biotechnology at the University of Guelph as a mature student at the age of 30. Then I went back to the zoo to lead the reproductive science program, knowing it was the only zoo in Canada that had committed to a science that can be forgotten. 

DP: When do you assist in reproduction at the zoo?

GM: Most of our animals do natural reproduction, and that’s the way we want it. But if they have a challenge, such as a behavioural or physical challenge, or sometimes we’re trying to move genetics around the world, then we assist. Genetic management and diversity is the number one reason we would do assisted reproduction.

DP: I understand you have brought tech-related innovations to your work. How so?

GM: When the zoo first started, we were focused on current technologies and sperm. I built out the embryo side and then an in-vitro fertilization lab and freezing embryos. About 15 years ago, I started a cell culture bank, where we preserve the cells of about 75 different animal species in liquid nitrogen tanks. In the future, we’re going to be doing reproduction with stem cell technologies, and for that to happen, we need cell cultures from genetically valuable animals. So now the Toronto Zoo has one of the most diverse — and the only wildlife — living cell banks in the world. Some of the research we’re doing is how to take these cells and convert them to become sperm and eggs and embryos.

DP: How do you deal with concerns around animal welfare and assisted reproduction?

GM: We are certified by the Canadian Council for Animal Care, which makes sure animals always get optimal care according to the latest evidence; right now we are the only zoo in Canada that has that certification. We are bound by the same animal use regulations as any university or research institute. We also have our own internal welfare science department. Before we do any procedure, it has to go through a couple of layers of internal approvals. 

DP: How does biodiversity in a zoo help in the wild?

GM: All our animals at the zoo have a purpose for why they are here. Some might be part of an education initiative to connect an animal here with a problem in their native home such as palm oil poaching or habitat loss, while others are involved in a release program. A lot of our species such as frogs, reptiles, and some fishes are part of our zoo population, but their offspring get released back into the wild. As well, zoos are like nature’s insurance policy. Genetic material is being safeguarded in a living animal and in our cell culture bank. In the event of a natural disaster or epidemic that impacts an animal population, we’ve protected genetic diversity and can use it to repopulate a species.

DP: I heard you thawed a batch of 35-year-old wood bison sperm.

GM: Yes, with our wood bison project, we’ve made sex-sorted calves: This is where you take the sperm and sort it to only give us the female sperm, and we made female calves. If you’re going to have a conservation herd, you need a lot of females. It’s been such an impactful program because we partnered with Parks Canada and the University of Saskatchewan to bring genetic material from the wild to encourage more genetic diversity. 

DP: What does your average day look like?

GM: I do a lot of hands-on work, but it’s very seasonal. I might go into the field for a week at a time to do some of that bison work. That takes place in Alberta and Saskatchewan. My primary day to day is really about building partnerships. I write a lot of grant proposals. I'm an adjunct professor at the University of Guelph, so I do a lot of teaching at universities; I’m engaged with universities to build out the training for the next generation of scientists. So, basically, I talk a lot and I write a lot.

DP: The Indianapolis Prize is a big deal. How do you feel about this nomination?

GM: It allowed me to look back and realize, I guess I have had some impact. Also, the nomination comes from my colleagues. Prize organizers permitted me to read the letters. It was so endearing that colleagues — both within and outside of the zoo — the picture they painted of my career and success. 

I have spent the majority of my career not focusing on myself, and I’m known for collaboration. The one thing about conservation is it cannot be done alone. It cannot be done in a silo. You have to build partnerships. And I guess over 25 years, I've been fairly effective at doing that.

If you wish to support the Toronto Zoo, you can visit, volunteer or donate to the Toronto Zoo Wildlife Conservancy.

Read more about how parks are rebuilding Prairie bison herds in Wanuskewin Heritage Park.