Camera traps offer an extraordinary view into the secret lives of wild animals, and have given us an unparalleled glimpse into the world of many rare and endangered species. Now a team of marine biologists are starting to use them to spy on the creatures that live not in rainforests or on mountains, but beneath the waves.

The researchers, led by Stony Brook University, plan on setting up underwater camera traps in 400 locations around the globe over a period of three years, making the project the largest-ever attempt to survey the world’s shark populations.

A multidisciplinary project, it has two main objectives: The first, "to learn what features of a coral reef influence how many sharks and rays either live around or visit that reef," Dr Demian Chapman, who's leading the study, told IFLScience. The second objective, Chapman adds, is to learn how sharks actually influence the health of the coral reef. "So we want to ask questions like: Do coral reefs with a lot of sharks recover faster from disturbance than reefs without sharks?"

They also aim to improve our understanding of the conservation status of chondrichthyan fishes – sharks and their relatives. In a recent review of the animals, the International Union for Conservation of Nature concluded that while a whopping 30% of sharks are at risk of extinction, there simply isn’t enough data to assess 46% of species. The Global Finprint project aims to change this.

4 reefs and a funeral from Global FinPrint on Vimeo.

“This global survey will fill in data gaps that could help governments, fisheries and others better understand and conserve these important predators,” explains Mike Heithaus, who is part of the international team involved in the study. With recent estimates that around 100 million sharks are being killed every year, it’s crucial that we understand how the animals fit in with their ecosystem, and how their removal is affecting it.

The researchers are going to place cameras that have a bait cage attached on the sea floor. If there are any sharks or rays within the vicinity of the setup, which is called a baited remote underwater video (BRUV), they should smell and then swim toward the bait, activating the camera. BRUV then runs for a full 80 minutes and records whatever sea critters come in to investigate the food, allowing the team to standardize the results across every site they sample.

The use of the BRUVs is a significant change in direction from most previous studies that have assessed shark populations in the past, which normally rely on physically catching the fish on lines or tracking them with tags. This way, the sharks in effect catch themselves – only on camera.

All the data will then be made available through an open-access database, including information on species density, habitats and diversity trends. The researchers hope that this will mean policy makers and conservation management teams will have all the necessary information at hand when forming plans and initiatives to identify and protect priority habitats.