School shark

What it is

The school shark is a small, slender houndshark with an elongated snout and a crescent-shaped mouth. Its teeth are small, triangular, and serrated, set at an angle facing backward. The first dorsal fin is triangular with a straight leading edge, positioned just behind the pectoral fins. The second dorsal fin is similar in size to the anal fin and sits directly above it. Adults are dark bluish grey on top and white underneath, while juveniles display black markings on their fins. Males typically reach 135 to 175 cm, whereas females grow larger, ranging from 150 to 195 cm.

Where it lives

This species inhabits temperate waters globally, preferring temperatures between 10 and 20 °C. It lives near the seabed at depths up to 800 metres. Populations exist in the Northeast Atlantic and Mediterranean, though they are uncommon there. In the Southwest Atlantic, it ranges from Patagonia to southern Brazil. It is also found off Namibia and South Africa. In the Pacific, it occurs from British Columbia to Baja California in the north, and off Chile and Peru in the south. Southern Australia, Tasmania, and New Zealand also host significant populations.

How it lives

School sharks are migratory and opportunistic feeders. Tagged individuals have travelled over 1,200 km along Australian coasts or crossed oceans from the UK to Iceland. They hunt in midwater and near the bottom, eating sardines, flatfish, rockfish, and squid. Uniquely, reef-dwelling individuals show a strong preference for barracuda, a predator-prey dynamic that fossil evidence suggests has existed for 50 million years. They are not known to be aggressive towards humans but are caught extensively in commercial fisheries.

Breeding and life cycle

Reproduction is ovoviviparous, meaning eggs hatch inside the uterus and embryos feed on yolk sacs. Males mature at 8 to 13 years, while females take 11 to 18 years. Gestation lasts about one year. Litter sizes average between 28 and 38 pups, depending on the mother's size. Females may store sperm, allowing pups in one litter to have different fathers. Births occur in sheltered bays and estuaries, which serve as nursery areas where juveniles remain while adults migrate to deeper waters.

Fish and people

Historically, this shark was vital for its liver oil, which has exceptionally high vitamin A content. During World War II, it supplied most of the vitamin A in the United States before stocks collapsed. Today, its meat is eaten fresh or preserved. In New Zealand, Māori traditions value it as kapetā, using oil for cosmetics. In Andalusia, it is known as cazón and served marinated. In Greece, it is called galéos and eaten with garlic dip. In the UK, it sometimes replaces cod in fish and chips. It remains a key commercial species in southern Australia.

Status and threats

The IUCN classifies the school shark as Critically Endangered due to severe overexploitation. Fisheries target it for liver oil, meat, and fins using gillnets and longlines. Nursery habitats face degradation from siltation, and deep-sea cables may disrupt migration via magnetic interference. Greenpeace listed it on its seafood red list in 2010. While New Zealand classifies it as Not Threatened domestically, it remains threatened overseas. Conservation efforts focus on managing fishing pressure and protecting pupping grounds.

Relatives and look-alikes

It is the only living member of the genus Galeorhinus. Fossil records show a similar extinct species, G. cuvieri, dating back to the Eocene. It is often confused with other houndsharks in the family Triakidae. In some markets, the term cazón refers to other shark species prepared in similar ways. It shares commercial importance in Australia with the gummy shark, though they are distinct species.

Questions people ask about School shark

Good reading and sources

• School shark on WikipediaEncyclopedia
• More photos on Wikimedia CommonsPhotos
• Wikidata recordOpen data