Port Jackson shark

What it is

This bullhead shark has a broad, blunt head with ridges above the eyes. Its body is grey-brown with dark, harness-like bands that cross the eyes and run along the back. Two dorsal fins of similar size sit near the rear, each preceded by a sharp spine. These spines are rumoured to be venomous. The mouth is small, and nostrils connect directly to it. Adults reach lengths of 1.65 metres, making them the largest in their genus.

Where it lives

The species lives in temperate coastal waters around southern Australia. Its range extends from southern Queensland down to Tasmania and west to central Western Australia. Rare sightings have occurred off New Zealand. It prefers rocky environments but also inhabits sandy bottoms, muddy areas, and seagrass beds. Sharks usually stay below 100 metres but can dive as deep as 275 metres.

How it lives

Active at night, this shark rests in caves or rocky outcrops during the day. It feeds on sea urchins, molluscs, and crustaceans, using specialised teeth to crush hard shells. Juveniles eat more soft-bodied prey. The shark can pump water over its gills while stationary, allowing it to breathe without swimming. Adults often rest in groups, showing preference for partners of similar sex and size.

Breeding and life cycle

Males mature at eight to ten years, females at eleven to fourteen. Breeding occurs annually from late August to November. Females lay pairs of eggs every eight to seventeen days, producing up to eight pairs per season. Eggs take ten to eleven months to hatch. Mortality rates for eggs are high, estimated at nearly ninety per cent, largely due to predation by other sharks.

Fish and people

This shark has no major commercial value and is not a common food source. It is generally harmless to humans, though one minor bite incident was recorded in Melbourne. Scientists use the species to study bottom-dwelling shark behaviour. It is sometimes caught as bycatch in fishing nets. Research has shown juveniles can learn to associate lights or sounds with food rewards.

Status and threats

The International Union for Conservation of Nature lists the species as Least Concern. However, egg mortality is very high. In New Zealand, it is classified as Vagrant with a Secure Overseas qualifier. Threats include predation on embryos by other sharks and incidental capture in fishing gear. Population trends remain largely unknown outside of these specific threats.

Questions people ask about Port Jackson shark

Good reading and sources

• Port Jackson shark on WikipediaEncyclopedia
• More photos on Wikimedia CommonsPhotos
• Wikidata recordOpen data