The Department of Environment has relaunched its Sharklogger Network, in which volunteer divers help monitor Cayman’s shark population.
The DoE decided that this week, which is Shark Week, was a good time to announce plans to restart the ‘citizen science’ programme that was halted last year due to COVID-19.
The Sharklogger Network was initially launched in 2016. It involves divers providing their dive logs that include reports on the presence or absence of sharks.
Eighteen volunteers have signed up and a number of organisations and dive operations, including the Central Caribbean Marine Institute, the Lobster Pot Dive Center, Ocean Frontiers, Divetech and Red Sail Sports Grand Cayman, have agreed to continue their participation.
Most of the volunteers had signed up previously, but have restated their interest in participating in the Sharklogger Network for the relaunch of the programme, Johanna Kohler, the DoE’s shark project research officer, said.
“Some were logging their dives each month, however, others had not logged since lockdown. So, we do actually have some limited data despite the reduced commercial diving due to COVID, which is fantastic because the standardized scientific shark research by DoE staff has been on hold during that time,” Kohler told the Cayman Compass in an emailed response to queries.
She added, “Even better, since the DoE social media post, we already have two new participants showing interest. But the more people who dive regularly who want to be a Sharklogger, the better the programme.”
The divers are asked to add all shark sightings to a ‘Shark Log’ – a spreadsheet provided by the DoE and designed specifically for the programme to help standardise the data. “Data quality is important for a statistically robust analysis and, ultimately, confidence in results,” Kohler said.
Anecdotally, there appears to have been an increase in the sighting of large sea animals, including sharks, in recent months. Kohler said that, while it may seem as though there have been more shark sightings lately, “this is likely due to more people being out and about on the beach and in the water during the calmer, longer summer days, which biases the trend, making it seem that sharks are more common over summer”.
She added, “But, interestingly, our research shows that Caribbean reef, nurse and hammerhead shark abundances are relatively stable throughout the year. There seems to be a slight shift in habitat in each species which may contribute as well, whereby people also see some species more in certain times of the year in certain areas.
“Also, sharks are somewhat shy creatures, so in some areas less people on and in the water may mean that the people who are out have a better chance of seeing a shark.”
Sharks, as apex predators, play an important role in keeping the balance of the marine environment. In 2015, when the National Conservation Law came into effect, sharks became legally protected animals in the Cayman Islands.
Despite that, sharks in Cayman waters are still vulnerable to fishing, coastal development, habitat degradation, pollution and climate change, Kohler said.
“Even if 100% protected, for changes in shark populations to occur, it takes decades, because of their life characteristics, such as slow growth, late maturity, low fecundity (small number of pups per litter). Hence, six years of protection is not enough for significant changes to occur in Cayman. The local community is great in helping with this effort by releasing accidentally caught sharks and helping us in monitoring the population. With time, we will be able to assess whether shark protection measures are sufficient and effective in protecting our sharks,” she said.
Sharks help the reefs by keeping prey populations healthy and in balance, by exerting top-down pressure which affects the entire food web and ecosystem. If they were to disappear, this would have a catastrophic effect, such as algae blooms.
“In the Cayman Islands, more algae means that our coral reefs will die, which can have a different negative effect on fish populations, so in order to keep our reefs and fish population healthy, we need sharks,” Kohler said.
She pointed out that, besides the ecological benefits, sharks are also of socio-economic value to Cayman. “A shark in Cayman is worth more alive than dead. Sharks are usually the highlight of any dive they are seen on and divers do travel around the world to see them.”
The non-consumptive economic value of sharks to the Cayman Islands, through tourism and recreation, has been estimated at US$46.8 million to $62.6 million a year, compared with an estimated consumptive use value, if sharks were sustainably fished, of no more than $1.3 million a year, according to a DoE survey.
Kohler said another DoE survey had shown that tourists who come to Cayman that don’t dive or snorkel or necessarily want to encounter a shark, still want to know that Cayman has a healthy shark population as the ecological benefits of sharks are widely known nowadays.
How to help
The department is inviting dive operators, as well as a frequent divers and snorkellers, to join the Sharklogger Network and contribute to local shark research, by emailing [email protected].