Around the world it has been shown how climate change is influencing temperatures and weather patterns Costa Rica does not escape this reality; experts warn about the impact on sharks and rays in the Cocos Island National Park.
According to research from the Center for Research in Marine Sciences and Limnology (Cimar-UCR), these species are at risk due to global warming. “The study revealed that due to global warming, the temperature of the ocean surface has increased, forcing rays and sharks to migrate to deeper waters,” highlights Cimar.
“But there is a limit to how far these species can dive, because at greater depths there is less oxygen, rays and sharks require a certain amount of oxygen to survive,” experts warn.
In addition, experts highlight that global warming also causes oxygen in the oceans to decrease. A situation that is generating an increasingly narrower strip of water where rays and sharks can live. The above, because it is located between what is known as the minimum oxygen layer and the surface waters heated by climate change.
According to the main researcher of the study, Mario Espinoza, “it is very likely that this same phenomenon is occurring in other areas of the Pacific Ocean, affecting other marine species.”
Some species increase, others decrease
Regarding the number of specimens of some species, Dr. Espinoza explained that the study found a decrease in the presence of the silky shark. “This is one of the most important species in fishing landings in Costa Rica,” he explained.
However, other species showed an increase in the study period, these are:
Marble stripe
Hammerhead shark
Galapagos Shark
Whitetip reef shark
Tiger shark
According to Espinoza, in the study 17 species of sharks and rays were recorded, of which:
15 species were observed between 50 and 100 meters deep
11 species in deeper dives between 300 and 400 meters
Fishing
Likewise, the co-author of the study, Dr. Tayler Clarke, warned that “these results have serious repercussions for the conservation of sharks and rays. “By occupying a smaller space in the water column, their capture is facilitated and without adequate management of fisheries, their vulnerability to overexploitation increases,” he highlighted.
To avoid overfishing, measures could be taken such as:
Expansion of existing marine protected areas
Creation of new protected areas.
Implement measures that impose greater limits and greater control over the fishery
Delimit the areas, times and depths where you can fish
Capture techniques used
“The study on Cocos Island is telling us that this situation could happen in other areas of the Pacific and the world, which is very worrying because it is evidence that not only shark and ray populations are affected by fishing. , but also that climate change could increase their vulnerability,” the experts highlight.
How was it determined?
To reach these conclusions, Cimar scientific staff monitored the behavior of the animals for 10 years, from 2010 to 2019. The observations were made with the help of the tourism company Undersea Hunter Group Company, which provided the DeepSee submarine to perform dives up to 400 meters deep.
These dives allowed the collection of a large amount of data and information, which was analyzed by the Cimar scientific team, the investigation details. “This is a unique study, since we rarely have such extensive time series in deep waters,” mentioned biologist Fabio Quezada.
“Most studies that have evaluated the status of shark and ray populations in the world are relatively short or focused on coastal and shallow environments, less than 40 meters. With which we would be losing valuable information about what is happening in deeper regions,” he added.
They also highlight the need to carry out monitoring in deeper areas of the ocean, integrating biological information on the species and environmental variables. “This will allow us to better understand the status of populations of threatened species and how they could adapt to climate change,” concluded the principal researcher. The results of this study, published in the international journal Scientific Reports of Nature.
