Broadnose sevengill shark

What it is

This shark has a thick body, broad head, and blunt snout. It is distinct for having seven gill slits instead of the usual five. The upper jaw holds jagged teeth while the lower jaw has comb-shaped ones. A single dorsal fin sits far back near the tail. The tail upper lobe is longer than the lower one. Its skin is silver-gray or brown on top with small black and white spots. The belly is pale to blend with sunlight from below. Juveniles often show white edges on their fins.

Where it lives

It lives in temperate waters across the Pacific and Atlantic Oceans. Sightings occur off China, Japan, Australia, New Zealand, Canada, the United States, Chile, Argentina, and South Africa. In San Francisco Bay, it is common near the Golden Gate Bridge. Most stay in shallow continental shelves, bays, and estuaries. Older individuals may dive to depths of 570 metres. In South Africa, they prefer sandy floors with some kelp.

How it lives

An opportunistic hunter, it eats sharks, rays, seals, and dead animals. It scavenges carcasses including drowned humans. Research shows mammals make up a large part of its diet. It hunts alone or in packs using stealth. After eating, it digests slowly for days. Orcas and larger sharks like the great white may prey on it. It patrols quietly near the sea floor. Activity levels are similar during day and night. Group formation may help avoid predators in open areas.

Breeding and life cycle

Females give birth to live young after a year-long pregnancy. Litters are large, containing over eighty pups. Birth happens in shallow bays during April and May. Newborns measure about forty centimetres. Males mature faster than females. Females reach reproductive age between twenty and twenty-five years. The species lives for around thirty years. Scientists have studied its hormones and reproduction to aid conservation.

Fish and people

Fisheries target it for liver oil and hide. Sport anglers catch it in tournaments. It is considered potentially dangerous to divers. Bites have been recorded but none were fatal. It adapts well to aquariums and is a keynote species in some facilities. Tourists often see it in temperate tanks. Apps allow divers to track sightings for research. Fishing is restricted in some areas like Washington state.

Status and threats

The IUCN lists it as Vulnerable globally. Threats include bycatch, pollution, and targeted fishing. Local declines occurred in San Francisco Bay due to intense fishing. New Zealand classifies it as Not Threatened but data poor. Conservation areas exist in South Africa and California. Recommendations suggest protecting Bahía Anegada in Argentina. Recreational limits apply in Victoria, Australia.

Questions people ask about Broadnose sevengill shark

Good reading and sources

• Broadnose sevengill shark on WikipediaEncyclopedia
• More photos on Wikimedia CommonsPhotos
• Wikidata recordOpen data