With so many species at risk due to human activities and climate change, it’s encouraging to hear about one that is doing well for itself: the oceanic manta ray population of over 22,000.Mobula birostris) off the coast of Ecuador.
The population is 10 times the number thought to be in other areas, and conservationists hope that the “unprecedented” group of manta rays can provide information about the conditions in which the fish thrive.
In 2019, the manta ray was also listed as endangered on the IUCN Red List of Threatened Species, and commercial fishing poses a serious threat to the species – whether by direct targeting or bycatch.
“It’s clear that there’s something different going on here,” says environmental scientist Joshua Stewart, of Oregon State University. “This is a very rare issue related to the hope of the sea. In some areas, we have a population of 1,000 to 2,000 animals, which makes this animal very difficult.”
Although it is clear that manta rays are endangered, it is not easy to study and monitor these animals: they spend a lot of time in hard-to-reach coastal areas, and their behavior can be unpredictable.
Since the late 1990s, scientists have been keeping a close eye on this group of manta rays off the coast of Ecuador. For this latest estimate, researchers used more than a decade of photos and videos taken between 2005 and 2018 to estimate the population of more than 22,000 people.
This means that the Isla de la Plata area is a favorite place for these fish. The group thinks that the abundance of food may be one of the reasons why the population is growing, with cold water, full of nutrients rising from the bottom and fed on ocean currents that provide a steady stream of zooplankton snacks.
“While there is good news about these people, it is a cautionary tale,” says Stewart. “Manta rays appear to be affected by environmental disturbances such as changes in sea temperature and food availability.”
“They will be affected by a warming climate if the pressure rises and the amount of food changes in line with the temperature of the ocean.”
Long-term studies like this are important because they give scientists a better idea of the world’s population. Quantitative and population comparisons are widely used in population comparisons, so it is important that marketers like this group M. birostris it is placed in.
The more accurate the data, the more effective the security measures can be. While catching manta rays in this part of the world is now illegal, issues like killing manta rays, fishing nets. bending and ship strikes remain a problem, alongside climate change – many fish appeared to be injured or scarred during surveys.
And the study is a success story for citizen science and manta rays. One of the main reasons that the population can be assessed (and more than 2,800 fish can be identified in more than 3,300 photos) is because of the photos sent by divers in the area.
Scientists identify manta rays in the images based on the unique pattern on their abdomens, similar to a human finger or the white spots on whale sharks. This allows researchers to count, track and monitor manta rays over time. Based on the observations and ray numbers, they can also estimate the population.
“Many of the images used in our research were contributed by hobbyists who became citizen scientists when they photographed manta rays,” says marine researcher Kanina Harty, from The Mantra Trust in the UK.
“We get a lot of information about each animal from these images.”
Research has been published in Marine Ecology Progress Series.
