Written by guest contributor - Yolanda Evans.

A small glimpse of grey amongst the the vibrant green of the kelp around the temperate coastal waters could be no other then the incredible Broadnose Sevengill shark! Hinted by their common name, these sharks have seven pairs of gill slits - unlike the typical five. These sharks can reach up to 3 metres long and are commonly misidentified as the other species of sevengill the Sharpnose Sevengill. The Broadnose is distinguished by small black and white freckles on their fins and underside and a much larger head then the Sharpnose. 

Unlike many other sharks in the Hexanidae family (Cowsharks), this species prefers waters of less then 50 m in depth; sometimes being found in river estuaries where the depth is around 1m! However, Brodnose’s make seasonal migration during the winter to the continental shelves, following their food and sexually mature females.

Broadnose Sevengill’s have a unique tooth shape in their lower jaws: they are shaped like combs which they use to anchor into their prey. This sharks favourite snacks large fish (including other sharks) and crustaceans but they have been videoed eating carrion (dead/decaying bodies), making them scavengers. There are even reports of cannibalism as the older sharks eat the younger to reduce competition. Once they’ve eaten a meal they wont have to eat again for weeks, in fact, in a month they only consume 6% of their body weight! 

Predominantly being a solitary shark, they do sometimes congregate in groups to hunt. They mainly do this to get to bigger prey which could be too much work for a single shark. Stalking behind their prey, these sevengill’s will then rapidly burst out to chase down their prey. 

Sevengill’ are ovoviviparous and can give birth to 60-180 pups, an incredibly high amount. The pups remain in the shallow waters until they reach a certain size to help avoid predators. 

Recent carcasses of these sevengill’s have been found worldwide, all with their livers missing. Who could be behind this series of surgically-precise murders other then the infamous Orca. Orca, or Killer Whales,purposefully seek out Broadnose Sevengill sharks for their livers rich in fats, making a high calorie snack for these mammals. The Orca turn the shark over on their backs, putting them in a state of tonic immobility, and then using their sharp conical teeth they precisely remove the liver leaving the rest of the shark as it doesn’t have the same nutritional value. However, a few videos have emerged of these Orcas then playing with their food, pushing the dead sharks body up and down with their snouts! 

Orca’s aren’t the only mammal to purposefully hunt down these sharks as the Broadnose Sevengill’s are also targeted by humans for their meat, skin for leather, and their oil, however, their main threat is being caught as by-catch during industrial fishing. The IUCN lists them as Data Deficient, however, it is expected that they are Near Threatened.

SCIENTIFIC NAME: Notorynchus cepedianus

FAMILY: Hexanchidae

MAXIMUM SIZE: Up to 3.3 meters (10.8 feet) in length

DIET: Feeds on a variety of prey including fish, squid, crustaceans, and even other sharks

DISTRIBUTION: Broadnose Sevengill Sharks have a cosmopolitan distribution, found in coastal and offshore waters in temperate and tropical regions worldwide.

HABITAT: Found in a variety of habitats, including estuaries, bays, and shallow reefs, as well as deeper waters of up to 150 meters (492 feet) in depth.

CONSERVATION STATUS:

While there is little data on population trends, this species is known to be caught as bycatch in some commercial and recreational fisheries, and there is also concern over the impact of habitat loss and degradation on their populations.

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