Valged haid kogunevad Atlandi ookeani uude levialasse

Suur valgehai (Elias Levy)
Suur valgehai (Elias Levy)

Valgehaide uusim ja potentsiaalselt tihedaim leviala on tuvastatud – ja selgub, et see asub Atlandi ookeani põhjaosas, Cape Codi lähedal Massachusettsis.

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.

Loe ka: Shark-sukeldumisoperaator esitab klientide vastu laimuhagid

Pikaajalist uuringut juhtis USA heategevusorganisatsiooni teadur Megan Winton Atlandi valgehai kaitseala (AWSC), töötades koos prof Gavin Fayga Massachusettsi ülikool Dartmouth's School for Marine Science and Technology (SMAST), kus Winton on doktorikraadi kandidaat, ja tuntud haide uurija dr Greg Skomal Massachusettsi merekalanduse osakonnast. 

Cape Cod oli kujunemas valgehaide hooajaliseks koondumiskohaks, kuid meeskond soovis saada täpseid andmeid kaitse- ja majandamismeetmete võtmiseks.

Algselt fotograafia ja video 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)
Suur valgehai uurija Megan Winton (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.

Hiljutised märgistamistoimingud on hõlmanud kiirendusmõõturi ja kaamera kinnitamist, et jälgida hai tegevust hetkest hetkeni.

“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.”  

Viimased uuringud suurte valgehaide kohta Cape Code'is (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.

Valgehai uuring avaldatakse ajakirjas Mereökoloogia edusari

Avastage "esimesi" 3D-hai mudeleid

Suur valgehai (uued interaktiivsed 3D-mudelid leiate nüüd World of Sharksi veebisaidilt (Byron Dilkes / SOSF)
Suur valgehai (Byron Dilkes / SOSF)

Šveitsis asuv Save Our Seas Foundation (SOSF) on oma World of Sharksi veebisaidile lisanud erinevatele platvormidele uusi interaktiivseid 3D valgehai ja mantaray mudeleid. Külastajaid kutsutakse uurima haide ja kiirte bioloogiat ja evolutsiooni, pöörates seda, mida SOSF nimetab oma "esimesteks" mudeliteks. Internetis

. veebisait 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.”

Täiustatud tehnikad tagavad, et mudelhaid on vormitruud ja esindavad ka ehtsat liikumist, ütleb SOSF.
Täiustatud tehnikad tagavad, et mudelhaid on vormitruud ja esindavad ka ehtsat liikumist, ütleb SOSF.

3D-mudelid kujundas koostöös SOSF-iga digitaalne Eluprojekt Massachusettsi ülikoolis. Avatud juurdepääsuga, neid saab mittetulunduslikuks kasutamiseks tasuta vaadata ja alla laadida.

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.

Samuti Divernetis: Valgehai puuri sukeldumiskomplekt Nova Scotiale, Kuidas puuris sukeldumine võib haidele positiivselt mõjuda, Sukelduja kohtumine vaalaga liiga lähedal, Cape Codi laevavrakilt leiti piraadiluud

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Keith Bolger
Keith Bolger
8 kuud tagasi

Näib, et pärast kõiki neid aastaid. Suur valgehai on lõpuks saanud koduvete kindlateks lemmikuteks, mille Jaws The Movies tegi nii kuulsaks, et nad tormavad elama filmides mainitud vetes.
Miks on teadlased nüüd nii üllatunud.
Fuck Sake'i pärast vaadake filme

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