Roughhead Grenadier

Macrourus berglax

SARA Status
No Status
NS
Special Concern
SC
Threatened
TH
Endangered
EN
Extirpated
EX

SARA Status

  • No Status NS
  • Special Concern SC
  • Threatened TH
  • Endangered EN
  • Extirpated EX
COSEWIC Status
Not at Risk
NR
Special Concern
SC
Threatened
TH
Endangered
EN
Extirpated
EX

COSEWIC Status

  • Not at Risk NR
  • Special Concern SC
  • Threatened TH
  • Endangered EN
  • Extirpated EX

Description

Roughhead Grenadier (Macrourus berglax) is one of only four Macrourus species in the world and the only one found in the North Atlantic. It belongs to the family Macrouridae, a family commonly referred to as “rattails”. It has the following characteristics:

  • Elongated body with a long, tapering, pointed tail;
  • Large, fairly broad head with ridges on top bearing strong, small spines;
  • A ridge (below each eye) extending from the snout tip to a lower corner of the gill cover;
  • Prominent, pointed snout, and a small barbel on its chin;
  • Body is ash grey in colour with a slightly darker chest, and anal fin has a narrow dark edge;
  • Can grow to 110 cm in length; and
  • Females have been aged up to at least 25 years.

Habitat

Roughhead Grenadier is found in the North Atlantic Ocean in temperate to arctic waters along the continental slope. In the eastern North Atlantic, this species is found from the Irish Atlantic Slope north to the Faroe Islands, Norwegian coast to Spitzbergen, and into the Barents Sea. In Canadian waters, Roughhead Grenadier has a continuous distribution and is most commonly found along the slope of the Labrador and Northeast Newfoundland Shelves, the northeastern slope of the Grand Bank, and off of the Flemish Cap. It occurs less commonly north to Baffin Bay and south to Georges Bank.

Roughhead Grenadier is a deep-sea fish that inhabits open water at depths of 400–1,200 m, and sometimes as deep as 2,740 m. It has a specialized swim bladder that prevents the leakage of oxygen through the bladder wall when under high pressure in deep water. This species is typically found at water temperatures of 2–5.4 °C, and rarely slightly below 0°C. Roughhead Grenadier is slow-growing, matures late in life, and produces few eggs relative to other cod-like fish. Eggs are fertilized externally during a spawning event (known as “batch” spawning) offshore, which may extend over an entire year. Females mature at 13–15 years of age and can live to 25 years of age. Males have a shorter lifespan.

Threats

Fishing is the principal threat to Roughhead Grenadier, which can be a significant bycatch in deepwater fisheries such as those targeting Greenland Halibut (Reinhardtius hippoglossoides). Directed fishing of Roughhead Grenadier has been under moratorium in North Atlantic Fisheries Organization Subareas 0, 2, and 3 since 1997.

Roughhead Grenadier populations are very susceptible to mortality caused by humans, because of their life-history characteristics (long lifespan, slow growth rate, late maturity, and low fecundity) that limit this species' recovery after a disturbance.

Further Information

For more information, visit the Species at Risk (SARA) Public Registry Profile.

Text Sources:

COSEWIC. 2007.  COSEWIC assessment and status report on the Roughhead Grenadier Macrourus berglax in Canada.  Committee on the Status of Endangered Wildlife in Canada. Ottawa. vii + 40 pp.

Roughhead Grenadier

Illustration of a Roughhead Grenadier

Illustration of a Roughhead Grenadier viewed from the side.
(Illustration: Gary Taylor)

The Roughhead Grenadier is ash grey in colour. It has a large head (approximately 25% of the total length of the body) with large eyes and a moderately slender body, tapering uniformly to a pointed tail. The head is fairly broad with ridges on top bearing strong, small spines. It has a prominent pointed snout that is equal to eye height. A small chin barbel is present.

Scientific name: Macrourus berglax
SARA status: No Status
COSEWIC status: Special Concern (April 2007)
Regions: Newfoundland and Labrador, Nunavut, and Nova Scotia

Did You Know?

Common names for the Roughhead Grenadier include Rattail, Onion-Eye, and Smooth-Spined Rattail. Inuit refer to it as “ingminniset”, which means “it bellows when dying”.

This species is distinguished from other grenadiers in the North Atlantic by its prominent pointed snout, a ridge (below each eye) extending from the snout tip to a lower corner of the gill cover, and ridges with strong, small spines on top of its broad head. Like many deepwater species, young grenadiers feed mainly on small bivalves, starfish, shrimp, and marine worms, then gradually switch to eating fish, shrimp, and large bivalves as they grow in length. Female Roughhead Grenadiers grow larger and heavier than males and can live to at least 25 years of age. The male Roughhead Grenadier has two large, drumming muscles on the front part of its swim bladder.

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