Regulars help research
Two of the Ningaloo Marine Park’s favourite annual visitors are believed to be the longest-studied wild sharks in the world, according to Murdoch University researchers.
Whale sharks Stumpy and Zorro have been coming to the Ningaloo coast for 22 years and have given researchers an extraordinary glimpse into the life of WA’s marine emblem.
One of the researchers watching over them as they matured has been Murdoch University research leader Brad Norman.
Dr Norman said the two 40year-old sharks had contributed significantly to the understanding of whale shark movements and identification methods.
“I started back in 1994 and I was using slide film to take photos of whale sharks,” he said.
“Everything is digital now, so it’s a lot easier to get more photos and monitoring done.
“Based on photographs of the shape and length of the claspers, which are the paired external reproductive organs of whale sharks up to 60cm long, Zorro first reached maturity in 1998 and Stumpy in 2001.”
Identifying both sharks is easy because of their unique tail fins but Mr Norman said extensive research had proved difficult at times as they may be sighted only once or twice a year.
Of more than 1300 whale sharks identified since research began off the Ningaloo coast, most sharks have been juvenile males who may hang around for only two or three years.
Dr Norman said the next frontier for research, of which he hoped Zorro and Stumpy would play a part, was to learn more about their breeding habits. “When they’re not at Ningaloo, they must go somewhere where they breed and that is still one of the big mysteries,” he said.
Stumpy and a swimmer off the Ningaloo coast.