Remote camera traps are now being used underwater to study shark behaviour for conservation research.
The Caribbean reef shark has a relatively short, broadly rounded snout
From land to sea
During the last decade, camera traps have become a popular tool with biologists and conservationists to monitor land-based wildlife, particularly threatened and elusive species such as the snow leopard. Now, this technology has been put to use in an entirely different realm – the oceans.
Sharks, like their feline counterparts, are threatened top predators, so between 2005 and 2010, a team of marine biologists from New York’s Stony Brook University deployed underwater video camera traps in Belize to monitor the population of Caribbean reef sharks found there.
The idea behind the baited camera traps, nicknamed ‘chum cams’, was to find out whether Marine Protected Areas, where fishing is entirely prohibited, are home to more sharks than non-protected areas. In total, 200 cameras were placed both inside marine reserves and in fishing zones in the Caribbean Sea.
Bony fish and large crustaceans are among the preferred prey species of the Caribbean reef shark
Feeding on film
The smell of the bait, or ‘chum’, attracted sharks to the camera traps, which enabled scientists to record, count and compare the shark populations in two different marine reserves, Glover’s Reef and Caye Caulker, with those found in two fishing zones.
According to the research, published in the journal PLoS One, sharks were caught on film at nearly four times as many camera sites within the marine reserves as in non-protected areas. Data from tagged sharks also revealed that many sharks remain in the protected areas year-round.
“Although we know that relatively sedentary reef fish and lobsters benefit from marine reserves, this study now presents visual proof that large, active sharks are also dramatically more abundant inside these protected areas, too,” said Mark Bond, lead author of the paper and doctoral student at the Institute for Ocean Conservation Science.
“These areas provide the sharks and other coral reef species a respite from fishing, which means decreased fishing mortality for the sharks and more prey for them to eat.”
Caribbean reef shark injured by a fishing hook
Sharks at risk
In recent decades, populations of many shark species have suffered steep declines, with the lucrative trade in fins for shark fin soup being a key contributor. The Caribbean reef shark, which is intensively fished and is also often caught as bycatch, is currently listed as Near Threatened on the IUCN Red List.
“Our study demonstrates that marine reserves can help protect shark species that live on coral reefs. Moreover, the use of underwater video monitoring provides us with an excellent tool to determine if populations are recovering and thriving inside these reserves,” concludes co-author Ellen K. Pikitch, executive director of the Institute for Ocean Conservation Science.
Further shark research, this time surrounding the concept of ecotourism, was also published this week in the British Ecological Society’s journal Functional Ecology. This study, by scientists at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science, revealed that the feeding of tiger sharks at offshore dive sites does not appear to adversely affect their behaviour.
Dive operations offering shark feeding tours have become a highly lucrative industry, and there were fears that feeding sharks could change the behaviour of the animals, making them more susceptible to threats. However, by using satellites to track the behaviour and movement of tiger sharks off Florida and in the Bahamas, the researchers discovered that this was not the case.
The researchers hypothesised that tiger sharks in the Bahamas, where chum is used to attract sharks for dives, would show restricted movements at the dive sites. However, the opposite was found to be true. Tiger sharks in the Bahamas site roamed over an area almost five times greater than tiger sharks in Florida, where the use of chum to attract sharks is illegal.
In a study conducted last year by co-author Neil Hammerschlag, results indicated that shark dive tourism generated more money for local economies than killing the animals for their fins.
He said, “Given the economic and conservation benefits, we believe managers should not prevent shark diving tourism out of hand until sufficient data were to demonstrate otherwise.”
Read more on this story at Mongabay.com – Camera traps go under the ocean, seeking sharks.
Read more about the shark and ecotourism story at CBC News – Ecotourism no threat to tiger shark behaviour.
Learn more about sharks on ARKive.
Kathryn Pintus, ARKive Species Text Author