In a rare record, researchers filmed dozens of black-haired sharks in Ilha Grande Bay in Angra dos Reis on the green coast of Rio de Janeiro. The species, considered endangered, was sighted swimming in a group this week, in the Piraquara de Fora Cove.
A study with the participation of the project Tubarões da Bay of Ilha Grande and the Brazilian Institute of Nature Conservation (Ibracon) points out that peaks of concentration occur between May and August, with up to 113 sharks registered in a single stretch of the cove. The findings were published in the first scientific article on the subject, in Aquatic Conservation magazine.
“We are facing a rare and relevant event for the conservation of coastal sharks in the South Atlantic. It is important to highlight that the presence of these animals is not a risk to bathers,” explains Fernanda Rolim, a USP researcher and the study author.
According to the research, one of the possible explanations for the concentration of sharks in the region is the search for warmer waters during autumn and winter months. As some of the registered individuals were pregnant females, the researchers suggest that this thermal variation may favor the presence of animals in this reproductive stage, as high temperatures benefit embryonic development and digestion, and may even reduce gestation time. The abundance of prey, such as mullets, can also contribute to the place to function as a food area.
“We have observed a consistent standard of return of these sharks to the same region, year after year. This indicates that the cove can have an important and predictable ecological function, which reinforces its potential as a priority area for conservation,” says Leonardo Mitrano Neves, scientific coordinator of the project.
The ecological importance of the place has also just been recognized internationally. Last week, the Piraquara de Fora Cove was officially included in the list of important areas for the International Union for the Conservation of Nature (IUCN). The authors of the study also propose the expansion of the protected area, especially during the winter.
“It is a region of great biodiversity, where diving tourism is strong and the ecosystem depends on key species, such as sharks. Ensuring the conservation of these predators is essential to maintain the balance of marine environments,” says Nathan Lagai of the Urban Mar Institute, which also integrates the study.
Black collar sharks feed on fish and are considered harmless. In adulthood, they can reach more than two meters in length and weigh more than 80 pounds. The species has a placental viviparous reproduction, in which the mother feeds the embryos directly through the placenta. The gestation period lasts between 10 and 12 months, with the birth of 1 to 10 puppies at a time.
This content was originally published in researchers filming dozens of black-granted sharks in Ilha Grande, in RJ on CNN Brazil.
Source: CNN Brasil
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