Study finds whale sharks home­bod­ies

Pilbara News - - News - Tom Zaun­mayr

Teenage hu­mans are well known for their abil­ity to lock them­selves in their rooms and never stray too far, and it seems young whale shark world may be no dif­fer­ent.

Re­searchers from the Univer­sity of West­ern Aus­tralia, Aus­tralian In­sti­tute of Ma­rine Sci­ence and col­lab­o­ra­tors across the In­dian Ocean have found ju­ve­nile male whale sharks don’t ven­ture too far from home.

The re­searchers used pho­toiden­ti­fi­ca­tion data, col­lected by ci­ti­zen sci­en­tist, in­clud­ing crews work­ing on the tour boats, and re­searchers, to as­sess the con­nect­ed­ness of five whale shark ag­gre­ga­tion sites across the In­dian Ocean over a decade.

Af­ter sift­ing through more than 6000 pho­tos, they found on av­er­age 35 per­cent of whale sharks were seen again at the same site in more than one year but no sharks were found to have moved across the In­dian Ocean.

UWA Oceans In­sti­tute and AIMS PhD re­searcher Sa­man­tha An­drze­jaczek said the re­searchers had ini­tially thought the ju­ve­niles crossed oceans to visit other im­por­tant sites dur­ing their mi­gra­tion.

“Whale sharks are un­der threat from hu­man im­pacts of hunt­ing and ship strike and it makes it much eas­ier to plan for con­ser­va­tion if we only have to deal with neigh­bour­ing coun­tries in each re­gion rather than lo­cal­i­ties spread across the en­tire In­dian Ocean,” she said.

“Our young males don’t seem in any hurry to move on from their feed­ing grounds at Nin­ga­loo — we have some in­di­vid­u­als that have now been sighted here for 19 years and have even ma­tured.”

Most of the whale sharks at Nin­ga­loo are male teenagers.

Study co-author Mark Meekan said adult whale sharks still proved elu­sive in the In­dian Ocean.

“We know the teenage males are home­bod­ies, but that does not nec­es­sar­ily ap­ply to the rest of the pop­u­la­tion,” he said.

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