Turns out that whale sharks  have an in-built sperm bank which allows them to fertilise hundreds of eggs at different times within their body and then stagger the births after mating just the once.

Perth researcher Brad Norman explains a new scientific discovery about one of the world’s threatened species – the whale shark.

Mr Norman was one of six researchers led by Chicago-based geneticist Jennifer Schmidt who analysed 29 preserved embryos from the first pregnant female whale shark ever to be caught.

He says varying the development of the embryos could be a way of protecting the species.

“By staggering the delivery of pups, the strategy serves to reduce the risk of losing an entire litter at any one location.

CHICAGO, Illinois — How do female whale sharks meet their perfect mates and go on to produce offspring? While little is known about the reproductive behavior of these ocean-roaming giants, a newly published analysis led by University of Illinois at Chicago biologist Jennifer Schmidt reveals new details about the mating habits of this elusive, difficult-to-study fish.

Schmidt, a UIC associate professor of biological sciences, determined paternity of 29 frozen embryos saved from a female whale shark caught off the coast of Taiwan in 1995. The embryos, studied in collaboration with Professor Shoou-Jeng Joung at the National Taiwan Ocean University, are extremely rare.

The pregnant shark carried a surprisingly large number of embryos — 304 — still in the uterus and representing a spectrum of age and development stages ranging from being still egg-encased to developed, near-term animals.

Schmidt and her colleagues spent several years developing DNA genetic markers to study whale sharks, initially for population genetics, but in this study the tool was used to determine paternity.