(DRAFT) - Taxonomy
Species halibut, Atlantic
Species Id M010088
Date 27 AUG 96
TAXONOMY
NAME - halibut, Atlantic
OTHER COMMON NAMES - grays, cherry bellies and Fr. fletan atlantique
ELEMENT CODE -
CATEGORY - Fish
PHYLUM AND SUBPHYLUM - ,
CLASS AND SUBCLASS - Osteichthyes,
ORDER AND SUBORDER - Pleuronectiformes,
FAMILY AND SUBFAMILY - Pleuronectidae,
GENUS AND SUBGENUS - Hippoglossus,
SPECIES AND SSP - hippoglossus,
SCIENTIFIC NAME - Hippoglossus hippoglossus
AUTHORITY - Linnaeus, 1758
TAXONOMY REFERENCES - 258 and 231
COMMENTS ON TAXONOMY -
Fr.: fletan atlantique
This species was called Hippoglossus vulgaris, even within recent years, in
parts of Europe but the valid name is H. hippoglossus.*258*
A closely related species, Hippoglossus stenolepis Schmidt, is important
commercially in the Pacific Ocean and may well be indistinguishable from H.
hippoglossus.*258*
The family pleuronectidae is a large family of benthic marine fishes
(occasionally found in brackish water; rarely in fresh water), closely
related to the percomorph fishes, inhabiting the Arctic, Atlantic, and
Pacific oceans. Bottom fishes of continental shore waters, often lying
partially concealed in mud or sand. The asymmetry and behavioral life
stages of righteye flounders are similar to those of Bothidae, the lefteye
flounders, the eyes migrating to the right side of the head in righteye
flounders, and the fish commencing to lie on the left side with the right
side (or eyed side) uppermost; sometimes called dextral flounders. Eggs
without an oil globule.
Body oval, sometimes elongated, laterally compressed; the mouth small to
large, asymmetrical, lower jaw more or less projecting; teeth usually small,
obsure, palatines, toothless; normally both eyes on right side of head may
be raised and moved independently; preopular margin free.*258*
Taxonomy - 1 (DRAFT) - Status
Species halibut, Atlantic
Species Id M010088
Date 27 AUG 96
STATUS
Coded Status
Commercial
Commercial/consumption
REFERENCES FOR STATUS - 258
COMMENTS ON STATUS -
Atlantic halibut is highly regarded as a food fish and commands a high
price. It is caught commercially by otter trawls and longlines.*258*
The commercial yield averaged around 2,268,000 kg for many years.
The catch has declined only slightly in recent years.*258*
The peak of Canadian landings occurred in 1950 when 5909 t were landed.
Halibut have a higher landed value per pound than other Atlantic groundfish,
making it economically feasible for fishermen to land relatively small
quantities. The white, flaky, and relatively dry flesh is not smoked but
marketed fresh and frozen.*258*
Status - 1 (DRAFT) - Distribution
Species halibut, Atlantic
Species Id M010088
Date 27 AUG 96
DISTRIBUTION
Distribution - 1 HABITAT ASSOCIATIONS
HABITAT - MARINE
REFERENCES FOR HABITAT - 258
LAND USE -
Water
REFERENCES FOR LAND USE - 258
COMMENTS ON HABITAT ASSOCIATIONS -
Atlantic halibut, largest of the flatfishes, ranges widley over Canada's
Atlantic fishing grounds. It avoids temperatures below about 2.5 degrees C
and tends to move from shallow water (<36.6 m) into deeper water in winter,
returning to shallow waters in summer. Young halibut appear to be most
available in shallow waters, 37-55 m, whereas large mature fish inhabit
deeper waters, 165-229 m.*258*
ANIMAL/PLANT SPECIES ASSOCIATIONS -
Greenland shark - Somniosus microcephalus
seals
Parasites: monogeneans, trematodes, cestodes, nematodes, acanthocephalans,
copepods*258*
REFERENCES FOR SPECIES ASSOCIATIONS - 258
COMMENTS ON SPECIES ASSOCIATIONS -
PREDATION AND COMPETITION: Larval and juvenile halibut undoubtedly fall
prey to other fishes but evidence appears to be lacking. The Greenland
shark Somniosus microcephalus and seals are said to prey on halibut.
However, in a study of 279 harbor seal stomachs, no evidence of halibut was
found.*258*
PARASITES AND DISEASE: The halibut is regarded as a very 'clean' fish by
fishermen and processors, but it is, nevertheless, host to a number of
external and internal parasites, including monogeneans, trematodes,
cestodes, nematodes, acanthocephalans, and copepods. Much of our knowledge
of the parasites of halibut results from a series of papers on parasites in
Gulf of St. Lawrence flatfishes . Researchers recorded the parasite fauna
of Atlantic halibut, listing 34 species. Infection by blood parasites in
one of seven specimens examined from the Labrador-Newfoundland area was
reported .*258*
Habitat Associations - 1 (DRAFT) - Food Habits
Species halibut, Atlantic
Species Id M010088
Date 27 AUG 96
FOOD HABITS
TROPHIC LEVEL -
CARNIVORE
REFERENCES FOR TROPHIC LEVEL - 258
LIFESTAGE FOOD FOOD PART
Juvenile Invertebrate Cordates Not Specified
Juvenile Annelids Not Specified
Juvenile Crustaceans Not Specified
Adult Invertebrate Cordates Not Specified
Adult Fish Not Specified
REFERENCES FOR ADULT FOOD - 258
REFERENCES FOR JUVENILE FOOD - 258
COMMENTS ON FOOD -
Atlantic halibut are voracious feeders. Up to a length of about 30 cm, food
consists almost exlusively of invertebrates, many marine annelid worms and
crustaceans such as crabs, decapod shrimp, and euphausiids. At 30-80 cm in
length both invertebrates and other fishes are eaten, but halibut over 80 cm
long feed almost exclusively on other fishes.*258*
COMMENTS ON ADULT FOOD -
At 30-80 cm in length both invertebrates and other fishes are eaten, but
halibut over 80 cm long feed almost exclusively on other fishes.*258*
COMMENTS ON JUVENILE FOOD -
Atlantic halibut are voracious feeders. Up to a length of about 30 cm, food
consists almost exlusively of invertebrates, many marine annelid worms and
crustaceans such as crabs, decapod shrimp, and euphausiids.*258*
Food Habits - 1 (DRAFT) - Environment Associations
Species halibut, Atlantic
Species Id M010088
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 Water Temperature: Specified in Comments
E
BA Water Depth Preference: Specified in Comments
A Water Temperature: Specified in Comments
A Water Depth Preference: Specified in Comments
REFERENCES FOR ENVIRONMENTAL ASSOC_ - 258
REFERENCES FOR ADULT ENVIRONMENTAL ASSOC_ - 258
REFERENCES FOR BREEDING ADULT ENVIRONMENTAL ASSOC_ - 258
REFERENCES FOR EGG ENVIRONMENTAL ASSOC_ - 258
COMMENTS ON ENVIRONMENTAL ASSOCIATIONS -
Available evidence indicates that spawning occurs at a depth of about 183 m
or greater. In the northeast Atlantic, halibut spawn at depths of 1000 m or
more.*258*
Eggs were most abundant in waters where temperature and
salinities ranged between 4.5 and 7.0 degrees C and 33.8 and 35.0 ppt.*258*
Atlantic halibut, largest of the flatfishes, ranges widley over Canada's
Atlantic fishing grounds. It avoids temperatures below about 2.5 degrees C
and tend to move from shallow water (<36.6 m) into deeper water in winter,
returning to shallow waters in summer. Young halibut appear to be most
available in shallow waters, 37-55 m, whereas large mature fish inhabit
deeper waters, 165-229 m.*258*
COMMENTS ON ADULT ENVIRONMENTAL ASSOC_ -
Atlantic halibut, largest of the flatfishes, ranges widley over Canada's
Atlantic fishing grounds. It avoids temperatures below about 2.5 degrees C
and tend to move from shallow water (<36.6 m) into deeper water in winter,
returning to shallow waters in summer. Young halibut appear to be most
available in shallow waters, 37-55 m, whereas large mature fish inhabit
deeper waters, 165-229 m.*258*
Environment Associations - 1 (DRAFT) - Environment Associations
Species halibut, Atlantic
Species Id M010088
Date 27 AUG 96
COMMENTS ON BREEDING ADULT ENVIRONMENTAL ASSOC_ -
Available evidence indicates that spawning occurs at a depth of about 183 m
or greater. In the northeast Atlantic, halibut spawn at depths of 1000 m or
more.*258*
COMMENTS ON EGG ENVIRONMENTAL ASSOC_ -
Eggs were most abundant in waters where temperature and
salinities ranged between 4.5 and 7.0 degrees C and 33.8 and 35.0 ppt.*258*
Environment Associations - 2 (DRAFT) - Life History
Species halibut, Atlantic
Species Id M010088
Date 27 AUG 96
LIFE HISTORY
MORPHOLOGY/DESCRIPTION: Body strongly laterally compressed, a typical
flatfish, normally lying on its left side, right side uppermost, very
occasionally reversed. Head about 25 percent of total length; mouth large,
its angle under the front of eye, lower jaw strong and projecting, strong
teeth in both jaws; eye well developed and projecting somewhat above
surface. Branchiostegals 7. Fins: soft rayed; dorsal 92-107, extending
from above eyes to caudal peduncle; caudal large and distinctly concave, not
rounded; anal 69-84, preceded by spine-like bone covered by skin in large
specimens, similar to dorsal but shorter, beginning below base of pectorals
and ending below posterior end of dorsal; vent just in front of beginning of
anal fin; pelvics small, below and in front of pectorals; pectorals just
posterior to gill cover, obliquely pointed on eyes side, short and rounded
on blind side. Scales covering head and body. Lateral line prominent and
arched over pectoral fin. Vertebrae 50 or 51. Commercially caught halibut
range from 2.3 to 56 kg in weight. Color variable, upper surface greenish
brown to very dark brown, color extending onto fins; lower side usually
strikingly white, occasionally mottled with gray ('grays') or mottled with
red ('cherry bellies').*258*
REPRODUCTION: The time and place of spawning for Atlantic halibut are of
great interest from a management viewpoint, but until relatively recent
times were largely unknown. Halibut are now known to spawn in late winter
and early spring in most of the Canadian area--mainly during February,
March, and April. However, the spawning grounds are not clearly defined.
Available evidence indicates that spawning occurs at a depth of about 183 m
or greater. In the northeast Atlantic, halibut spawn at depths of 1000 m or
more. A female weighing 90.7 kg may produce over 2 million eggs. The eggs
are spherical and about 3.0 mm in diameter. They are of neutral buoyancy
and float at intermediate depths greater than 54 m but tend to sink toward
the bottom as development proceeds. Experimental work indicated halibut
eggs would float in salinities greater than about 37 ppt. However, field
studies in Norwegian fiords indicated specific density of the egg is
important. Eggs were most abundant in waters where temperature and
salinities ranged between 4.5 and 7.0 degrees C and 33.8 and 35.0 ppt.
Incubation takes 16 d at a temperature of about 6 degrees C, but the length
of time the larvae are pelagic is not known.*258*
GROWTH: Atlantic halibut have a more rapid rate of growth than any other
flatfish, particularly at ages over 10 yr. The lengths at various ages
determined by researchers for Gulf of St. Lawrence halibut are given in
Table 1. Table 2 gives weights at various lengths based on a sample of 269
male and female halibut from Western Bank, Scotian Shelf.*258
Table 1
Length, FL (cm)
Age
(yr) Males Females
5 61.0 58.4
10 91.4 104.1
15 129.5 145.1
Life History - 1 (DRAFT) - Life History
Species halibut, Atlantic
Species Id M010088
Date 27 AUG 96
20 147.6 170.5
25 154.9 185.7
Table 2
Length (cm) Weight (kg)
41.0 0.7
60.0 2.4
80.0 5.9
100.0 12.1
120.0 12.7
Females grow faster than males after the first few years and attain a much
larger maximum size. Studies indicated that older and larger male and
female halibut were taken in the Gulf of St. Lawrence than off western Nova
Scotia, although the difference in the growth rate of males from the two
regions was greater than for females. Studies also noted that halibut from
the Gulf of St. Lawrence and Scotian Banks grew at about the same rate as
those from Greenland, possibly slightly faster than those off northern
Norway, and more slowly than those from the Faroes. A recent study suggests
that there has been a marked decrease in the length at maturity. In the
period 1959-69 the length at which 50 percent of individuals reached
maturity was 84 cm for males and 98 cm for females, but in the period
1970-79 the lengths declined significantly to 66 cm for males and 70 cm for
females. The figures suggest the population is being heavily cropped.*258*
Halibut are aged by reading the growth rings on the otoliths, or 'ear
stones', but the older the fish the more difficult it is to interpret the
growth rings. Very large fish are estimated to be in the range of 30-35 yr
old.*258*
The halibut is one of the largest species occurring in the Canadian Atlantic
area. Very large specimens in excess of 90 kg seem now to be most ununsual
but researchers reported a specimen caught in the Gulf of Maine in 1917,
noting that "since it weighed 615 pounds, eviscerated with the head still
attached,... it must have been as heavy as 700 pounds when alive." Average
sizes range upward from 4.5 kg, depending on fishing ground and gear. The
largest Atlantic halibut taken by angling listed by the International Game
Fish Association weighed 113.4 kg caught off Gloucester, MA, in 1981.*258*
PREDATION AND COMPETITION: Larval and juvenile halibut undoubtedly fall
prey to other fishes but evidence appears to be lacking. The Greenland
shark Somniosus microcephalus and seals are said to prey on halibut.
However, in a study of 279 harbor seal stomachs, no evidence of halibut was
found.*258*
PARASITES AND DISEASE: The halibut is regarded as a very 'clean' fish by
fishermen and processors, but it is, nevertheless, host to a number of
external and internal parasites, including monogeneans, trematodes,
cestodes, nematodes, acanthocephalans, and copepods. Much of our knowledge
of the parasites of halibut results from a series of papers on parasites in
Gulf of St. Lawrence flatfishes . Researchers recorded the parasite fauna
Life History - 2 (DRAFT) - Life History
Species halibut, Atlantic
Species Id M010088
Date 27 AUG 96
of Atlantic halibut, listing 34 species. Infection by blood parasites in
one of seven specimens examined from the Labrador-Newfoundland area was
reported .*258*
LIFE HISTORY CODES -
Breeding/Spawning Season: February
Breeding/Spawning Season: March
Breeding Spawning Season: April
Average Number of Offspring/Reproductive Effort: Grea
REFERENCES FOR LIFE HISTORY- 258
Life History - 3 (DRAFT) - Management Practices
Species halibut, Atlantic
Species Id M010088
Date 27 AUG 96
MANAGEMENT PRACTICES
Management Practices - 1 (DRAFT) - References
Species halibut, Atlantic
Species Id M010088
Date 27 AUG 96
References
258 * Scott, W.B., M.G. Scott. 1988. Atlantic Fishes of Canada.
Canadian Bulletin of Fisheries and Aquatic Sciences (219) (ed.).
University of Toronto Press Toronto, Canada:731.
References - 1