The secret life of whale sharks no longer a mystery

The secret life of whale sharks no longer a mystery
Samantha Reynolds with a whale shark. Credit: Janine Marx

Whale shark researchers have marked International Whale Shark Day by solving a long-standing mystery about where the world's largest fish go during the Australian spring and summer.

In a world-first, researchers from The University of Queensland and the non-profit ECOCEAN have tracked and recorded a full return migration of whale sharks to and from Ningaloo Reef in Western Australia.

UQ graduate and ECOCEAN marine biologist Samantha Reynolds said the study revealed surprising insights into the importance of the Ningaloo Reef area.

"Our tagged whale sharks were tracked returning to Ningaloo Reef throughout the year, and our modelling suggests that it provides suitable habitat for them year-round," Ms Reynolds said.

"The eco-tourism industry takes visitors swimming with whale sharks at Ningaloo Reef in autumn and winter, but until now the creatures' whereabouts at other times of the year has remained a mystery.

"Whale shark season at Ningaloo could last all year," Ms Reynolds said.

"This is valuable information for the eco-tourism industry and could provide a boon for the local Ningaloo economy.

"It's also vital information for the long-term management and conservation of whale sharks.

"They are an endangered species. We need to know which areas are critical habitat for them, so we can protect them into the future."

The secret life of whale sharks no longer a mystery
Credit: University of Queensland

Ms Reynolds said the work had been part of the most extensive satellite tracking study of whale sharks in Australia.

It identified areas along the WA coast, in the Timor Sea and in Indonesian and international waters that could be important habitat.

"Our study highlights the need for international co-operation for the protection of whale sharks," Ms Reynolds said.

"Many of these areas are not designated as Marine Protected Areas and some of the tagged sharks we studied travelled to areas where they could be under threat from ship strike, pollution or targeted fishing.

"The conservation status of whale sharks was changed from vulnerable to endangered last year, because of these threats."

Whale sharks (Rhincodon typus) are slow-moving filter-feeding carpet , living to 80 years, with the largest confirmed individual weighing about 21.5t with a length of 12.65m.

The research, published in Diversity and Distributions, continues this month with more satellite tagging.


Explore further

Whale sharks shown to favour much of the Western Australian coastline

More information: Samantha D. Reynolds et al. Movement, distribution and marine reserve use by an endangered migratory giant, Diversity and Distributions (2017). DOI: 10.1111/ddi.12618
Journal information: Diversity and Distributions

Citation: The secret life of whale sharks no longer a mystery (2017, August 30) retrieved 22 July 2019 from https://phys.org/news/2017-08-secret-life-whale-sharks-longer.html
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