Tubarões brancos reúnem-se – num novo hotspot do Atlântico

Grande tubarão branco (Elias Levy)
Grande tubarão branco (Elias Levy)

O hotspot mais recente e potencialmente mais denso para grandes tubarões brancos foi identificado – e verifica-se que se encontra nas águas do Atlântico Norte, ao largo de Cape Cod, em Massachusetts.

A team of researchers conducted an intensive “mark-recapture” survey to produce what they say is the first estimate of white shark abundance ever produced in the western North Atlantic.

Now, after eight years of fieldwork and analysis, they have revealed that approximately 800 individual sharks visited Cape Cod between 2015 and 2018.

Veja também: Operadora de mergulho com tubarões abre processos por difamação contra clientes

O estudo de longo prazo foi liderado por Megan Winton, cientista pesquisadora de uma instituição de caridade dos EUA. Conservação do tubarão branco do Atlântico (AWSC), trabalhando com o Prof Gavin Fay do Universidade de Massachusetts Dartmouthda Escola de Ciência e Tecnologia Marinha (SMAST), onde Winton é candidato a doutorado, e o notável pesquisador de tubarões, Dr. Greg Skomal, da Divisão de Pesca Marinha de Massachusetts. 

Cape Cod estava a emergir como um local de agregação sazonal de tubarões brancos, mas a equipa queria obter dados precisos para informar medidas de conservação e gestão.

Inicialmente fotografia e vídeo footage was used to identify the distinctive physical features of 393 individual sharks.

However, because this approach did not make full allowance for the great whites’ migratory behaviour, the researchers undertook an intensive mark-recapture survey. 

Megan Winton (SMAST)
Megan Winton, pesquisadora do grande tubarão branco (SMAST)

This technique involves capturing and tagging a number of individual sharks before releasing them back into the population.

As further groups are captured for tagging, the proportion already tagged is noted and, the bigger the population, the fewer tagged sharks are likely to be recaptured. 

Altogether 130 research trips were carried out in the process of developing a reliable model that would accommodate shark movements in and out of the surveyed area, and variations in residency and habitat use.

This has now resulted in the “superpopulation” estimate of 800 individuals, with the sharks tending to arrive when sea temperatures are warmest, in summer and early autumn.

As operações de marcação mais recentes incluíram a instalação de um acelerômetro e uma câmera para rastrear as atividades do tubarão a cada momento.

“We’ve found that white sharks are more intelligent, more social and more numerous than previously known,” says Winton.

“Cape Cod is the only area in the region where researchers can feasibly monitor the population, and our estimates suggest that the Cape is among the larger white shark hotspots worldwide, which is good news from a conservation standpoint.”  

As últimas pesquisas sobre grandes tubarões brancos em Cape Code (AWSC)

Concerns about public safety have been expressed around Cape Cod over the past decade as increasing numbers of sharks were spotted, and especially after a fatality occurred in the region at the end of the study period in 2018.

However, the team underline in their report that the risk to recreational water-users from great white sharks remains low. 

The sharks arrive with a rich diet of seals and smaller marine life in mind.

They are thought to have been increasingly attracted to Cape Cod because of its recovering population of grey and harbour seals, which had been hunted almost to extinction in the region before the US Marine Mammal Protection Act came into force in the early 1970s.

The regional population of these seals is now thought to number 30-50,000.

O estudo do grande tubarão branco é publicado na revista Série de Progresso da Ecologia Marinha

Explore modelos de tubarão 3D “primeiros do tipo”

Grande tubarão branco (novos modelos 3D interativos agora podem ser encontrados no site World of Sharks (Byron Dilkes/SOSF)
Grande tubarão branco (Byron Dilkes / SOSF)

The Swiss-based Save Our Seas Foundation (SOSF) has added new interactive 3D white shark and manta ray models across various platforms on its World of Sharks website. Visitors are invited to investigate the biology and evolution of sharks and rays by rotating what SOSF calls its “first-of-their-kind” models online

A site do Network Development Group includes infographics, podcast episodes, species cards and topic pages. “We wanted World of Sharks to be the ultimate shark FAQ – created to answer all the questions people want to ask about sharks and rays,” says CEO Dr James Lea.

“The key to all our understanding of sharks – why they do what they do and what is needed to help them recover – relies on there being a foundation of basic, reliable life history information.”

Técnicas avançadas garantem que os modelos de tubarões tenham uma forma fiel e também representem movimento genuíno, afirma a SOSF
Técnicas avançadas garantem que os modelos de tubarões tenham uma forma fiel e também representem movimento genuíno, afirma a SOSF

The 3D models were designed in collaboration with the SOSF by the Digital Life Project at the University of Massachusetts. Open-access, they are free to view and download for non-profit use.

Founded in 2003, SOSF’s stated aim is to secure the health and sustainability of the oceans, and the communities that depend on them, for future generations.

Its support for research, conservation and education projects worldwide focuses on endangered sharks, rays and skates, and it has permanent research and education centres in Seychelles, South Africa and the USA.

Também na Divernet: Conjunto de mergulho em gaiola de tubarão branco para a Nova Escócia, Como o mergulho em gaiola pode ser positivo para os tubarões, Encontro de baleia muito próximo do mergulhador, Ossos de pirata encontrados em navio naufragado em Cape Cod

VAMOS MANTER CONTATO!

Receba um resumo semanal de todas as notícias e artigos da Divernet Máscara de mergulho
Não fazemos spam! Leia nosso política de privacidade para mais informações.
Subscrever
Receber por
convidado

1 Comentário
Mais votados
Recentes mais velho
Comentários em linha
Ver todos os comentários
Keith Bolger
Keith Bolger
meses 8 atrás

Parece que depois de todos esses anos. O Grande Tubarão Branco finalmente se tornou o favorito das águas que ficaram famosas por Tubarão, o Filme, tanto que eles estão correndo para fixar residência nas águas mencionadas nos filmes.
Agora, por que os cientistas estão tão surpresos?
Pelo amor de Deus, assista aos filmes

Entre em contato

1
0
Adoraria seus pensamentos, por favor, comente.x