(DRAFT) - Taxonomy
Species hake, silver
Species Id M010597
Date 27 AUG 96
TAXONOMY
NAME - hake, silver
OTHER COMMON NAMES - silver hake and whiting
ELEMENT CODE -
CATEGORY - Fish
PHYLUM AND SUBPHYLUM - ,
CLASS AND SUBCLASS - Osteichthyes,
ORDER AND SUBORDER - Gadiformes,
FAMILY AND SUBFAMILY - Gadidae,
GENUS AND SUBGENUS - Merluccius,
SPECIES AND SSP - bilinearis,
SCIENTIFIC NAME - Merluccius bilinearis
AUTHORITY - Mitchill, 1814
TAXONOMY REFERENCES - 258 and 231
COMMENTS ON TAXONOMY -
Fr.: merlu argente
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*
Taxonomy - 1 (DRAFT) - Status
Species hake, silver
Species Id M010597
Date 27 AUG 96
STATUS
Coded Status
Commercial
Commercial/consumption
REFERENCES FOR STATUS - 258
COMMENTS ON STATUS -
Silver hake are generally frozen in blocks for human consumption. A limited
amount of silver hake appears on the domestic market as fresh or frozen
fillets, or fresh or frozen, dressed whole fish.*258*
Status - 1 (DRAFT) - Distribution
Species hake, silver
Species Id M010597
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 OW0
REFERENCES FOR NWI - 258
COMMENTS ON HABITAT ASSOCIATIONS -
A benthic species occurring over a wide range of depths, from the shallows
at the head of the Bay of Fundy, where they may be abundant or stranded at
low tide, to depths of over 910 m.*258*
ANIMAL/PLANT SPECIES ASSOCIATIONS -
cod
pollock
swordfish
spiny dogfish
silver hake (cannabalistic)
Parasites: Anthocotyle (a monogenean), Clestobothrium crassicieps (a
cestode), Anisakis simplex and Thynnascaris adunca (nematodes), and Caligus
curtus, C. elongatus, and Chondracanthus merlucci (copepods)*258*
REFERENCES FOR SPECIES ASSOCIATIONS - 258
COMMENTS ON SPECIES ASSOCIATIONS -
PREDATION AND COMPETITION: Because of their abundance, silver hake are
eaten by many other fishes, including cod, pollock, swordfish, and spiny
dogfish. The pelagic young are also eaten by many pelagic predators.
Silver hake are cannibalistic and at times small silver hake, especially 1
and 2 yr olds, may constitute up to 12.6 percent of the diet of large silver
hake. Silver hake and red hake are regarded as food competitors.*258*
PARASITES AND DISEASE: The silver hake has a limited parasite fauna;
researchers list only one monogenean, Anthocotyle merlucii, one cestode,
Clestobothrium crassiceps, two nematodes, Anisakis simplex and Thynnascaris
adunca, and three copepods, Caligus curtus, C. elongatus, and Chondracanthus
merlucci. Another copepod, Sphyrion lumpi, was reported from specimens
caught off Maine. Infection by a blood parasite (piroplasm) was detected in
one of 52 specimens from the Labrador-Newfoundland area.*258*
Habitat Associations - 1 (DRAFT) - Food Habits
Species hake, silver
Species Id M010597
Date 27 AUG 96
FOOD HABITS
TROPHIC LEVEL -
CARNIVORE
REFERENCES FOR TROPHIC LEVEL - 258
LIFESTAGE FOOD FOOD PART
Adult Gadiformes Not Specified
Adult Clupeiformes Not Specified
Adult Atheriniformes Not Specified
Adult Squid, Octopus Not Specified
Adult Crustaceans Not Specified
Adult Fish Not Specified
Adult See Comments; Food
REFERENCES FOR ADULT FOOD - 258
COMMENTS ON FOOD -
Silver hake have long been regarded as voracious predators, as indeed they
are. Larger hake, over 20 cm long, are generally nocturnal feeders, but
smaller fish seem to feed through the day. They consume many species,
especially gadids, including their own young (cannibalism). They also feed
heavily at times on pelagic species, including Atlantic herring, gaspereau,
myctophids, smelt, silversides, mackerel, sand lance, butterfish,
snakeblennies, and longhorn sculpins. They are opportunistic feeders and
consume large quantities of squid when available.*258*
In western Scotian Shelf waters gadids made up 51.2 percent of food;
crustaceans, especially euphausiids, made up 28.4 percent; and unidentified
fishes the remainder.*258*
Crustaceans, especially euphausiids, and small fishes are important prey of
small silver hake. As silver hake increase in size, fishes become
increasingly important prey; large hake are considered to have a depressing
effect on the populations of 1-or-2-yr-old silver hake. The control
exercised by large silver hake on the population size of their own species
may be quite significant.*258*
COMMENTS ON ADULT FOOD -
Silver hake have long been regarded as voracious predators, as indeed they
are. Larger hake, over 20 cm long, are generally nocturnal feeders, but
smaller fish seem to feed through the day. They consume many species,
especially gadids, including their own young (cannibalism). They also feed
heavily at times on pelagic species, including Atlantic herring, gaspereau,
myctophids, smelt, silversides, mackerel, sand lance, butterfish,
snakeblennies, and longhorn sculpins. They are opportunistic feeders and
consume large quantities of squid when available.*258*
In western Scotian Shelf waters gadids made up 51.2 percent of food;
crustaceans, especially euphausiids, made up 28.4 percent; and unidentified
fishes the remainder.*258*
Food Habits - 1 (DRAFT) - Food Habits
Species hake, silver
Species Id M010597
Date 27 AUG 96
Crustaceans, especially euphausiids, and small fishes are important prey of
small silver hake. As silver hake increase in size, fishes become
increasingly important prey; large hake are considered to have a depressing
effect on the populations of 1-or-2-yr-old silver hake. The control
exercised by large silver hake on the population size of their own species
may be quite significant.*258*
Food Habits - 2 (DRAFT) - Environment Associations
Species hake, silver
Species Id M010597
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: Below 15 degrees C
A Water Depth Preference: Specified in Comments
A Water Temperature: Below 15 degrees C
REFERENCES FOR ENVIRONMENTAL ASSOC_ - 258
REFERENCES FOR ADULT ENVIRONMENTAL ASSOC_ - 258
REFERENCES FOR EGG ENVIRONMENTAL ASSOC_ - 258
COMMENTS ON ENVIRONMENTAL ASSOCIATIONS -
Eggs hatch in about 48 h at water temperatures of 20-22 degrees C, but
normal development occurs at 12.2-15.6 degrees C.*258*
A benthic species occurring over a wide range of depths, from the shallows
at the head of the Bay of Fundy, where they may be abundant or stranded at
low tide, to depths of over 910 m. Its depth distribution is determined in
large measure by temperature. It prefers warmer water than that preferred
by most gadid fishes. Studies cited preferred temperatures of 6-8 degrees C
on the Scotian Shelf and noted that silver hake moved into shallower water
as summer progressed and waters warmed.*258*
COMMENTS ON ADULT ENVIRONMENTAL ASSOC_ -
A benthic species occurring over a wide range of depths, from the shallows
at the head of the Bay of Fundy, where they may be abundant or stranded at
low tide, to depths of over 910 m. Its depth distribution is determined in
large measure by temperature. It prefers warmer water than that preferred
by most gadid fishes. Studies cited preferred temperatures of 6-8 degrees C
on the Scotian Shelf and noted that silver hake moved into shallower water
as summer progressed and waters warmed.*258*
COMMENTS ON EGG ENVIRONMENTAL ASSOC_ -
Eggs hatch in about 48 h at water temperatures of 20-22 degrees C, but
normal development occurs at 12.2-15.6 degrees C.*258*
Environment Associations - 1 (DRAFT) - Life History
Species hake, silver
Species Id M010597
Date 27 AUG 96
LIFE HISTORY
MORPHOLOGY/DESCRIPTION: Body elongate, rounded to anus, laterally
compressed posteriorly. Head pointed, lower jaw projecting; mouth large,
jaws with two or more rows of sharp recurved teeth; eye large. Gill rakers
on first arch long, slender, 15-22. Branchiostegals 7. Fins: dorsals, 2,
first of 11-14 rays, second 37-42; caudal weakly forked; anal, 1, 38-42;
pelvics slightly anterior to, and smaller than, pectorals; pectorals 13-17.
Scales small, cycloid. Lateral line complete, almost straight, 103-130
scales. Peritoneum dusky, reddish. Vertebrae 54. Size averages about
30.5-40.6 cm long and about 0.5 kg in weight. Color silvery and iridescent
when fresh from water, soon fading to brownish or dark gray above; silvery
on sides, silvery white below. Fins transparent, but upper fins often
black-edged, lower fins white-edged; axil and edge of pectoral fin blackish;
inside of mouth, near throat, dusky blue.*258*
REPRODUCTION: Spawning occurs from June to September, peaking usually in
July and August; it may occur over a wide area of the continental shelf from
Sable Island Bank westward. A few ripe and spawning fish have been noted on
the Scotian Shelf as early as March, but most spawning occurs in July. A
principal spawning area on Sable Island and western banks was noted by
researchers.*258*
The eggs are 0.82-1.0 mm in diameter, buoyant, spherical, and transparent
and have an oil globule about 0.25 mm in diameter. They remain pelagic in
the water column for a few days until hatching. Eggs hatch in about 48 h at
water temperatures of 20-22 degrees C, but normal development occurs at
12.2-15.6 degrees C.*258*
GROWTH: Larvae are 2.6-3.5 mm long on hatching, and are pelagic for 3-5 mo,
when they move down in the water column and seek bottom. The lengths of
pelagic larvae taken on the Scotian Shelf indicated that spawning occurred
progressively from east to west and continued for some weeks at each
site.*258*
Determination of growth rates for silver hake has been hampered by
difficulties in interpreting growth lines on otoliths. Growth is fairly
rapid. They attain lengths of about 20 cm at 1 yr, 28 cm at 2 yr, and 33 cm
at 3 yr. Three-year-old females may range from 28 to 44 cm long, depending
on attainment of sexual maturity. Many silver hake attain sexual maturity
at age 2 yr, and almost all over 32 cm long or 3 yr of age were mature.
Maximum age is about 12 yr. Largest sizes were reported as 37 cm for males
and 65 cm for females. Maximum size to about 76 cm and a weight of about
2.3 kg.*258*
PREDATION AND COMPETITION: Because of their abundance, silver hake are
eaten by many other fishes, including cod, pollock, swordfish, and spiny
dogfish. The pelagic young are also eaten by many pelagic predators.
Silver hake are cannibalistic and at times small silver hake, especially 1
and 2 yr olds, may constitute up to 12.6 percent of the diet of large silver
hake. Silver hake and red hake are regarded as food competitors.*258*
PARASITES AND DISEASE: The silver hake has a limited parasite fauna;
Life History - 1 (DRAFT) - Life History
Species hake, silver
Species Id M010597
Date 27 AUG 96
researchers list only one monogenean, Anthocotyle merlucii, one cestode,
Clestobothrium crassiceps, two nematodes, Anisakis simplex and Thynnascaris
adunca, and three copepods, Caligus curtus, C. elongatus, and Chondracanthus
merlucci. Another copepod, Sphyrion lumpi, was reported from specimens
caught off Maine. Infection by a blood parasite (piroplasm) was detected in
one of 52 specimens from the Labrador-Newfoundland area.*258*
LIFE HISTORY CODES -
Breeding/Spawning Season: June
Breeding/Spawning Season: July
Breeding/Spawning Season: August
Breeding/Spawning Season: September
Display Site: Water
Average Number of Offspring/Reproductive Effort: Grea
REFERENCES FOR LIFE HISTORY- 258
Life History - 2 (DRAFT) - Management Practices
Species hake, silver
Species Id M010597
Date 27 AUG 96
MANAGEMENT PRACTICES
Management Practices - 1 (DRAFT) - References
Species hake, silver
Species Id M010597
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