Investigating baby sharks in a changing world

Climate change threatens shark populations worldwide, second only to fishing. Increasing ocean temperatures and decreasing pH and oxygen will impact all marine life, but sharks may be particularly vulnerable. They grow slowly, take a long time to mature, do not produce as many young as other fish species, and therefore may be unable to adapt fast enough to keep pace with climate change.

The Physioshark Project, led by Coral CoE’s Dr Jodie Rummer and primarily based on Moorea, French Polynesia, has been investigating how climate change stressors affect newborn sharks since 2013. Because all 4.7 million km² of French Polynesian waters comprise a shark sanctuary — the largest in the world – shark fishing/exploitation is banned. This provides a rare opportunity to study resident shark populations in the absence of their number one stressor. But, even the best-managed marine sanctuaries are not immune to climate change.

The physioshark project collects data from neonate and juvenile blacktip reefsharks and sicklefin lemonsharks around Moorea, French Polynesia. Credit: Tom Vierus @tomvierusphotography

The Physioshark team has been characterising and closely monitoring environmental conditions at 11 potential shark nursery areas around the island. They have been executing field and laboratory-based experiments on newborn blacktip reef and sicklefin lemon sharks to understand how they respond to environmental conditions they currently face. Their most recent publication (Bouyoucos et al., 2018) evaluates the physiological status and survival of neonatal reef sharks under stress.  The team found that, even under the best environmental and handling conditions, it takes newborn blacktip reef sharks over eight hours to recover from exercise. In the wild, this could be after a predator-prey interaction or if they are accidentally caught and released by fishers. The team is now starting to model sharks’ responses to conditions predicted with climate change to understand how habitat availability may change over time and the sharks’ capacity to adapt. This information will be key to understanding the efficacy of shark conservation tools, including sanctuaries.

To learn more, watch this short video that debuted at the New York City Wildlife Conservation Film Festival on 21 October 2018 and was the cornerstone of a community event on shark conservation at The Reef HQ Great Barrier Reef Aquarium on 4 October 2018.

The team has also been committed to communicating about shark biology and research via social media (instagram and facebook) and at the community level. Through these avenues, the team discusses why sharks are vulnerable in a changing world and why it is crucial to protect them. Through lab visits and school presentations, the Physioshark team educates the public, especially the youth, about the importance of sharks, gaining support from the communities they depend on for accessing field sites, and conveying appreciation for the opportunity to do research on Moorea.

Dr. Rummer’s PhD candidate, Ian Bouyoucos setting up a respirometry experiment in the physioshark lab. Credit: Tom Vierus @tomvierusphotography

Beyond maintaining ecosystem balance, sharks are also of economic and cultural significance. Tourism is French Polynesia’s largest income source, which relies on healthy marine ecosystems including shark populations. Traditionally, sharks also play a significant role in local culture and are represented in numerous Polynesian legends. Through outreach and education, the Physioshark team can help ensure that sharks maintain a high profile and that Polynesians understand current and future threats sharks face and what they can do to protect them and, thus, a part of their heritage.

Follow the project on instagram and facebook #physioshark @physioshark