AQWA’s ‘Eggstraordinary’ Port Jackson pup

A premature Port Jackson shark has beaten the odds in what is a wonderful story of care, expertise and dedication for AQWA’s team of aquarists and marine scientists.

Port Jackson sharks, affectionately known as PJ’s, are a protected native Australian shark. Only 10% of Port Jackson shark eggs will survive to hatching.

One PJ hatchling, now residing at AQWA, has an even greater feat under its fins thanks to the dedication and expert care of AQWA’s curatorial team.

For those unfamiliar with the wild world of shark reproduction, some species give birth to live young, while others lay eggs, like the Port Jackson.

The tough pup in question ‘hatched’ from its protective egg case at approximately 3 months, while standard incubation is closer to 10 or 11 months.

Shark egg cases are not the typical hard-shelled eggs. Instead, they feature a translucent yet tough, leathery case.  Perfectly camouflaged among the foliage and soft growth of seafloors and reefs, these spiral shaped eggs are hidden by female PJ’s ‘screwing’ them into crevices to keep them safer from predators.

Of course, it’s what’s inside that counts. Shark embryos are sustained by a connected yolk-sack within the egg case.

Pj’s typically breed from late winter to end of spring and this is no different for the sharks in our care. Over this period our aquarists actively search for eggs to remove and take into nursery holds – because unfortunately, shark eggs are a tasty treat, even to other PJs, and are often preyed upon when left in aquaria.

In 2023 a total of 10 eggs were removed with inspections showing only 4 had early signs of fertilization. Three eggs quickly demonstrated excess fluid and minute crustacea inhabiting the egg, meaning they were compromised or likely never fertilized.

But that fourth and final egg showed the shadow of a growing embryo!

Upon inspection, a crack was detected in the case which would likely have resulted in the embryo failing to develop. The team made the decision to create an incision and remove the case to allow monitoring of the embryo and connected yolk sack.

Placed into facilities where conditions best replicated those inside an actual egg, the embryo was allowed to ‘feed’ from the yolk and mature while being monitored by the team.

The fascinating process of rearing a caseless, premature shark embryo had begun. Our team were lucky enough to witness up close the progressive development of gills, teeth, fins and skin, including the striking dark markings and shapes PJ’s are known for.

As the yolk depleted and the embryo edged towards full gestation, the team began providing the pup with typical first-foods and the opportunity to feed.

Pleasingly, the little shark with a slim chance of survival began to eat, grow and is now thriving!

For biologists, shark lovers and curious observers alike, the footage captured is a sight to behold – be sure to watch the video above to witness this pup grow before your eyes!