A captive breeding program may help prevent the aquarium trade from eradicating its most illustrious client.
The clownfish is perhaps the world’s most widely-recognised reef fish. Aqua Immersion/Flickr (CC BY-NC-ND 2.0)
Since its 2003 release, Pixar’s Finding Nemo has inspired a generation of ocean lovers and marine biologists, and instilled conservation values into children globally. Following the film’s success, title character Nemo was thrust into the spotlight and is now one of the most recognisable fish in the world. Unfortunately, the film also had an unexpected and damaging impact on its star species, the clownfish.
The popularity of this charismatic reef fish skyrocketed after the release of Finding Nemo. More and more people wanted to see and interact with clownfish, but not necessarily in their natural habitat: Everyone wanted a pet Nemo.
But all those fish have to come from somewhere.
An alarming 90% of all aquarium fish have been wild harvested, resulting in around a million fish being removed from reefs globally each year. This number includes not only clownfish, but also blue tang (Dory in Finding Nemo), moorish idol (Gill), and a range of other popular aquarium species. To meet increasing demand for these species, more fish are being harvested each year, causing local population declines of up to 75% in some regions. Indonesia, the Philippines, and Thailand are popular locations for clownfish harvesting, but these practices also occur in Australia, the Maldives and Hawaii, among others.
Moorish idol (left) and blue tang (right) are both especially vulnerable to overharvesting for the aquarium trade. Ted/Flickr (CC BY-SA 2.0); Nathan Rupert/Flickr (CC BY-NC-ND 2.0)
Wild harvesting practices not only reduce population numbers but also disrupt the surrounding coral ecosystem. A popular method for collecting aquarium species is cyanide fishing, in which cyanide is used to stun the fish, making them easier to catch. Unfortunately, this practice damages the surrounding coral, causing mortality of both corals and the invertebrates that hide in them. The loss of clownfish from their anemones makes their hosts more vulnerable to predators and climate-induced coral bleaching events.
To reduce the number of wild reef fish collected and sold for the aquarium trade, a more sustainable alternative is desperately needed. Luckily for clownfish, they are easily bred in captivity, providing a sustainable way to keep clownfish as pets. Unfortunately for Dory, blue tangs are much harder to breed in captivity; despite the first successful captive breeding of blue tangs in 2016, there is not enough supply to meet demand.
There are a range of benefits from adopting a captive breeding strategy. Captive-bred fish live longer in consumer tanks than wild-harvested fish, due to the stressful transition from ocean to tank. Further, juveniles from captive breeding programs can be released back onto reef ecosystems to restore wild population numbers.
The Saving Nemo initiative began in 2007 as a clownfish breeding program at Flinders University, intended to reduce the number of wild-sourced clownfish sold into the aquarium trade and raise awareness for the plight of aquarium fish species. A decade on, the program has grown to include both educational and research programs and a thriving breeding centre. Through educational programs, both on campus at Flinders University and at schools throughout Australia, Saving Nemo reaches thousands of students each year, teaching them about the aquarium trade, climate change and scientific hypothesis testing.
Saving Nemo involves Australian schoolkids in the captive breeding of reef fish. © Saving Nemo
The Saving Nemo Clownfish Club, set to launch next year, will take the breeding program to the next level. Schools around Australia will be invited to maintain their own clownfish breeding tanks, to increase marine science education in the classroom and provide hands-on learning opportunities for students. By moving juvenile fish between different schools, we can also increase genetic diversity within the breeding program.
Finding Nemo and its sequel introduced generations of children to the wonderful clownfish. The least we can do is educate the public to ensure that the aquarium trade doesn’t wipe out its biggest and brightest star.
Cassie Hoepner is affiliated with the Saving Nemo Conservation Organisation. Edited by Andrew Katsis.
