(DRAFT) - Taxonomy
Species cusk
Species Id M010087
Date 27 AUG 96
TAXONOMY
NAME - cusk
OTHER COMMON NAMES - cusk, tusk, torsk and Fr. brosme
ELEMENT CODE -
CATEGORY - Fish
PHYLUM AND SUBPHYLUM - ,
CLASS AND SUBCLASS - Osteichthyes,
ORDER AND SUBORDER - Gadiformes,
FAMILY AND SUBFAMILY - Gadidae,
GENUS AND SUBGENUS - Brosme,
SPECIES AND SSP - brosme,
SCIENTIFIC NAME - Brosme brosme
AUTHORITY - Muller, 1776
TAXONOMY REFERENCES - 258
COMMENTS ON TAXONOMY -
In the family of codfish, medium to large-sized bottom fishes, living in
cool seas, except for one freshwater holarctic genus, Lota. Found mainly in
the northern hemisphere. Most species are bottom fishes inhabiting inshore
waters and continental shelves, some to depths of 1300 m.
Cods are generally heavy-bodied, elongate, usually with a stout caudal
peduncle. Head large: mouth large; teeth usually well developed on upper
(premaxillary) and lower jaws and on head of vomer; eye moderate. Gill
rakers usually short and stubby. Branchiostegals 6-8. Fins are well
developed. Scales cycloid, small. Lateral line well developed. Swim
bladder without pneumatic duct (physoclistous). Vertebrae 42-82. Color
generally somber, ranging from tan to brown to silvery. Predaceous fishes
feeding heavily on other fishes and invertebrates.
The cods are of great economic importance and support extensive commercial
fisheries.*258*
The cranial osteology of cusk was studied and compared with similar
structures in the genera Urophycis, Gadus, and Merluccius.*258*
Taxonomy - 1 (DRAFT) - Status
Species cusk
Species Id M010087
Date 27 AUG 96
STATUS
Coded Status
Commercial/consumption
REFERENCES FOR STATUS - 258
COMMENTS ON STATUS -
The cusk is a commercial groundfish species of limited importance, caught
mainly as a by-catch when seeking other species; Canadian catches are mainly
from the western portion of the Scotian Shelf. Because of the rough bottom
cusk inhabit, they are more often caught by longlines than by otter trawl.
The flesh is white, flaky, and of good flavor. It is sold fresh, frozen,
and smoked.*258*
Status - 1 (DRAFT) - Distribution
Species cusk
Species Id M010087
Date 27 AUG 96
DISTRIBUTION
Distribution - 1 HABITAT ASSOCIATIONS
HABITAT - MARINE
REFERENCES FOR HABITAT - 258
LAND USE -
Water
REFERENCES FOR LAND USE - 258
NATIONAL WETLAND INVENTORY CODES
NWI NWICLS NWIMOD NWISPEC
Marine UB1 2
REFERENCES FOR NWI - 258
COMMENTS ON HABITAT ASSOCIATIONS -
The cusk lives somewhat sluggishly, on hard, rough or rocky bottom,
usually at depths of 73-363 m, temperatures of 2-12 deg C, and salinities
of 32-34 ppt, along the Scotian Shelf. The preferred depths, temperatures,
and salinity of 128-144 m, 6-10 deg C, and 34 ppt. It is noteworthy that
cusk seem to prefer relatively warm water and intermediate depths.*258*
ANIMAL/PLANT SPECIES ASSOCIATIONS -
Hooded seal
trematode (Prosorhynchus squamatus)
REFERENCES FOR SPECIES ASSOCIATIONS - 258
COMMENTS ON SPECIES ASSOCIATIONS -
Predation and competition: In Greenland waters a cusk was removed from the
mouth of a hooded seal. The somewhat sluggish nature of cusk may make them
more susceptible to seal predation when within depth range.*258*
Parasites and disease: Little is known of the parasites of the cusk. Only
the trematode Prosorhynchus squamatus is listed.*258*
Habitat Associations - 1 (DRAFT) - Food Habits
Species cusk
Species Id M010087
Date 27 AUG 96
FOOD HABITS
TROPHIC LEVEL -
CARNIVORE
REFERENCES FOR TROPHIC LEVEL - 258
LIFESTAGE FOOD FOOD PART
General Crustaceans Not Specified
General Malacostraca Not Specified
General Molluscs Not Specified
General Starfish Not Specified
REFERENCES FOR GENERAL FOOD - 258
COMMENTS ON FOOD -
Direct observations of the food of cusk are meager. Examination of stomachs
of commercially caught cusk is usually unsuccessful because the stomachs
evert during capture and contents are lost. In European waters it is said
to feed on crustaceans, especially crabs and molluscs and occasionally
starfish. Presumably the diet is similar in Canadian waters.*258*
Food Habits - 1 (DRAFT) - Environment Associations
Species cusk
Species Id M010087
Date 27 AUG 96
ENVIRONMENTAL ASSOCIATIONS
G = General A = Adult
LIM = Limiting RA = Resting Adult
J = Juvenile FA = Feeding Adult
RJ = Resting Juvenile BA = Breeding Adult
FJ = Feeding Juvenile P = Pupae
L = Larvae E = Egg
RL = Resting Larvae
FL = Feeding Larvae
LIFESTAGE ENVIRONMENTAL ASSOCIATIONS
E Aquatic Habitat Zonation: Open water [pelagic zone]
E Aquatic Habitat Zonation: Specified in Comments
L Aquatic Habitat Zonation: Open water [pelagic zone]
L Aquatic Habitat Zonation: Specified in Comments
G Substrate: Rocks
G Substrate: Specified in Comments
G Water Depth Preference: 200-500 ft.
G Water Depth Preference: 500-1000 ft.
G Water Depth Preference: 1000-1500 ft.
G Water Depth Preference: Specified in Comments
G Water Temperature: Below 15 degrees C
G Water Temperature: Specified in Comments
G
G
BA Water Depth Preference: 500-1000 ft.
BA Water Depth Preference: Specified in Comments
REFERENCES FOR ENVIRONMENTAL ASSOC_ - 258
REFERENCES FOR BREEDING ADULT ENVIRONMENTAL ASSOC_ - 258
REFERENCES FOR LARVAE ENVIRONMENTAL ASSOC_ - 258
REFERENCES FOR EGG ENVIRONMENTAL ASSOC_ - 258
COMMENTS ON ENVIRONMENTAL ASSOCIATIONS -
The cusk lives somewhat sluggishly, on hard, rough or rocky bottom,
usually at depths of 73-363 m, temperatures of 2-12 deg C, and salinities
of 32-34 ppt, along the Scotian Shelf. The preferred depths, temperatures,
and salinity of 128-144 m, 6-10 deg C, and 34 ppt. It is noteworthy that
cusk seem to prefer relatively warm water and intermediate depths.*258*
COMMENTS ON BREEDING ADULT ENVIRONMENTAL ASSOC_ -
The reproductive biology of the cusk is not widely known for the northwest
Atlantic. It is suggested that spawning takes place from May to August but
that most spawning occurred in the last two weeks of June, and usually
occurred in depths less than 183 m. In the Gulf of Maine spawning is
somewhat earlier, April-July. Cusk are prolific. It was reported that
100,000 eggs were found in a fish 56 cm TL and 3,927,000 eggs for one 90 cm
Environment Associations - 1 (DRAFT) - Environment Associations
Species cusk
Species Id M010087
Date 27 AUG 96
TL. Cusk fecundity is approximately proportional to the cube of the length.
The eggs, 1.3-1.5 mm in diameter, are spherical, buoyant, and pelagic ith a
coppery tint and a pinkish oil globule. The surface of the egg is finely
pitted.*258*
Environment Associations - 2 (DRAFT) - Life History
Species cusk
Species Id M010087
Date 27 AUG 96
LIFE HISTORY
Description: Body robust, elongate, cylindrical before anus, laterally
compressed posteriorly. Head large, upper jaw slightly protruding; mouth
large; several rows of sharp teeth on jaws, vomer, and palatines; barbel on
chin equal to or greater than eye diameter; eye moderate. Gill rakers
11-13, broad, snout tubercles with small spines. Branchiostegals 7. Fins:
dorsal, 1, 85-105 rays; caudal rounded, confluent with dorsal and anal;
anal, 1, 62-75 rays; pelvics small, no elongate rays; pectorals brush-like.
Scales small, cycloid. Lateral line complete, arched over pectorals.
Vertebrae 64 or 65. Size to length 101 cm TL and weight of 12.3 kg. Color
variable, dark reddish or greenish brown, sometimes lighter brown, shading
to cream or white on belly. Median fins same as body color at bases, with
black near margins and white on edges.*258*
Reproduction: The reproductive biology of the cusk is not widely known for
the northwest Atlantic. It is suggested that spawning takes place from May
to August but that most spawning occurred in the last two weeks of June, and
usually occurred in depths less than 183 m. In the Gulf of Maine spawning
is somewhat earlier, April-July. Cusk are prolific. It was reported that
100,000 eggs were found in a fish 56 cm TL and 3,927,000 eggs for one 90 cm
TL. Cusk fecundity is approximately proportional to the cube of the length.
The eggs, 1.3-1.5 mm in diameter, are spherical, buoyant, and pelagic ith a
coppery tint and a pinkish oil globule. The surface of the egg is finely
pitted.*258*
Growth: Hatching occurs when embryos are about 4 mm long. The young remain
pelagic until they are about 50 mm long, when they seek bottom. The growth
rate of young fish seems not to be documented. However, in general, males
were longer than females at a given age. Male cusk from the Scotian Shelf
mature at a younger age than females. Some males were mature at 5 yr of age
and all were mature by age 10. Some females were mature at 6 yr and all by
10 yr. Fifty percent maturity for males occurs at 4.7 yr and 43.5 cm; 50
percent of females mature at 6.5 yr and 50.7 cm. The oldest specimen was 14
yr old, a male, 95.0 cm TL, weighing approximately 9.0 kg. Commercially
caught cusk average about 55-65 cm long and about 7-10 yr of age. Otoliths
are used for age determination.*258*
Predation and competition: In Greenland waters a cusk was removed from the
mouth of a hooded seal. The somewhat sluggish nature of cusk may make them
more susceptible to seal predation when within depth range.*258*
Parasites and disease: Little is known of the parasites of the cusk. Only
the trematode Prosorhynchus squamatus is listed.*258*
LIFE HISTORY CODES -
Breeding Spawning Season: April
Breeding/Spawning Season: May
Breeding/Spawning Season: June
Breeding/Spawning Season: July
Breeding/Spawning Season: August
Average Number of Offspring/Reproductive Effort: Grea
Life History - 1 (DRAFT) - Life History
Species cusk
Species Id M010087
Date 27 AUG 96
REFERENCES FOR LIFE HISTORY- 258
Life History - 2 (DRAFT) - Management Practices
Species cusk
Species Id M010087
Date 27 AUG 96
MANAGEMENT PRACTICES
Management Practices - 1 (DRAFT) - References
Species cusk
Species Id M010087
Date 27 AUG 96
References
References - 1