(DRAFT) - Taxonomy
Species pollock
Species Id M010599
Date 26 AUG 96
TAXONOMY
NAME - pollock
OTHER COMMON NAMES - pollock, Boston bluefish, harbor pollock, pollack, blister-back, coalfish, green cod, saithe, coley, merlan noire and merlan colin
ELEMENT CODE -
CATEGORY - Fish
PHYLUM AND SUBPHYLUM - ,
CLASS AND SUBCLASS - Osteichthyes,
ORDER AND SUBORDER - Gadiformes,
FAMILY AND SUBFAMILY - Gadidae,
GENUS AND SUBGENUS - Pollachius,
SPECIES AND SSP - virens,
SCIENTIFIC NAME - Pollachius virens
AUTHORITY - Linnaeus, 1758
TAXONOMY REFERENCES - 258 and 231
COMMENTS ON TAXONOMY -
Fr.: goberge
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 pollock
Species Id M010599
Date 26 AUG 96
STATUS
Coded Status
Sport Fish
Commercial
Commercial/consumption
REFERENCES FOR STATUS - 258
COMMENTS ON STATUS -
Pollock are commercially important and are caught by otter trawl, longline,
handline, weirs, and traps. Browns Bank, the Scotian Shelf, and the mouth
of the Bay of Fundy are centers of commercial fishing.
The flesh is slightly darker than cod or haddock flesh but is flaky and of
fine flavor. It is sold fresh, frozen, salted, and smoked. Usually
marketed as Boston bluefish in Canada.*258*
Status - 1 (DRAFT) - Distribution
Species pollock
Species Id M010599
Date 26 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 -
The pollock, of all the cod-like fishes, spends less time on bottom and
more time moving freely through the water column than does its
bottom-living relatives. Studies on the Scotian Shelf indicated a broad
overall depth range of 37-364 m and a preferred depth range of 110-181
m.*258*
ANIMAL/PLANT SPECIES ASSOCIATIONS -
harbor seals
pollock (cannibalism)
Parasites: Hemiuris levinseni (trematode), Echinorhynchus gadi
(acanthocephalan)
REFERENCES FOR SPECIES ASSOCIATIONS - 258
COMMENTS ON SPECIES ASSOCIATIONS -
PREDATION AND COMPETITION: Pollock appear to have few enemies. Pelagic
larval pollock probably fall prey to many predators but no reports have been
published. Some cannibalism has been noted. Adult pollock are eaten
occasionally by harbor seals.*258*
Pollock and silver hake eat similar foods and thus are competitors.*258*
PARASITES AND DISEASE: Helminth parasites of the alimentary tract were
studied by researchers who found 11 species as follows: trematodes (6),
nematodes (2), cestodes (2), and acanthocephalan (1). Trematodes were the
most common, especially Hemiuris levinseni. Anisakine nematodes and the
acanthocephalan Echinorhynchus gadi were next most common. Findings
indicated different levels of infection in pollock from the central Scotian
Shelf region, compared with pollock from the southwestern section,
suggesting separate populations of pollock in the two regions.*258*
In a review of parasites of pollock researchers listed 10 species or species
groups: one protozoan, one monogeneid, two trematodes, one nematode, one
acanthocephalan, and four copepods.*258*
A light infection by blood parasites was detected in specimens from the
Labrador-Newfoundland area.*258*
Habitat Associations - 1 (DRAFT) - Food Habits
Species pollock
Species Id M010599
Date 26 AUG 96
FOOD HABITS
TROPHIC LEVEL -
CARNIVORE
REFERENCES FOR TROPHIC LEVEL - 258
LIFESTAGE FOOD FOOD PART
Larva Copepods Not Specified
Juvenile Crustaceans Not Specified
Juvenile Fish Not Specified
Adult Crustaceans Not Specified
Adult Fish Not Specified
Adult Clupeiformes Not Specified
Adult Gadiformes Not Specified
Adult Atheriniformes Not Specified
Adult See Comments; Food
REFERENCES FOR ADULT FOOD - 258
REFERENCES FOR JUVENILE FOOD - 258
REFERENCES FOR LARVAE FOOD - 258
COMMENTS ON FOOD -
Pelagic larval pollock live largely on copepods. Following the larval
stage, the young move into shallow waters and eat small crustaceans,
especially amphipods. With increase in size, euphausiids, shrimps, and
small fishes become increasingly important for year-old pollock. When they
move offshore , euphausiids, especially Meganyctiphanes norvegica, become
important food for Bay of Fundy populations, but on the Scotian Shelf and in
the Laurentian Channel, fishes were more important foods. Fishes eaten in
the Bay of Fundy and Scotian Shelf include herring, sand lance, silver hake,
redfish, spotted lanternfish, and silversides.*258*
In a review of food of adult pollock along the Atlantic seaboard, studies
noted that fish and crustaceans were eaten in nearly equal proportions, but
larger pollock ate more fish than smaller ones did. In the Gulf of Maine
region, the average fork length of pollock was 64.5 cm, greater than for
fish from Georges Bank or western Nova Scotia, and fish, especially Atlantic
herring, was the most important food.*258*
COMMENTS ON ADULT FOOD -
With increase in size, euphausiids, shrimps, and
small fishes become increasingly important for year-old pollock. When they
move offshore , euphausiids, especially Meganyctiphanes norvegica, become
important food for Bay of Fundy populations, but on the Scotian Shelf and in
the Laurentian Channel, fishes were more important foods. Fishes eaten in
the Bay of Fundy and Scotian Shelf include herring, sand lance, silver hake,
redfish, spotted lanternfish, and silversides.*258*
In a review of food of adult pollock along the Atlantic seaboard, studies
Food Habits - 1 (DRAFT) - Food Habits
Species pollock
Species Id M010599
Date 26 AUG 96
noted that fish and crustaceans were eaten in nearly equal proportions, but
larger pollock ate more fish than smaller ones did. In the Gulf of Maine
region, the average fork length of pollock was 64.5 cm, greater than for
fish from Georges Bank or western Nova Scotia, and fish, especially Atlantic
herring, was the most important food.*258*
COMMENTS ON JUVENILE FOOD -
Following the larval stage, the young move into shallow waters and eat small
crustaceans, especially amphipods.*258*
COMMENTS ON LARVAE FOOD -
Pelagic larval pollock live largely on copepods.*258*
Food Habits - 2 (DRAFT) - Environment Associations
Species pollock
Species Id M010599
Date 26 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
BA Water Depth Preference: Specified in Comments
A Water Temperature: Below 15 degrees C
A Water Depth Preference: Specified in Comments
REFERENCES FOR ENVIRONMENTAL ASSOC_ - 258
REFERENCES FOR ADULT ENVIRONMENTAL ASSOC_ - 258
REFERENCES FOR EGG ENVIRONMENTAL ASSOC_ - 258
COMMENTS ON ENVIRONMENTAL ASSOCIATIONS -
Pollock eggs hatch in about 9 d at 6 degrees C and 6 d at 9.5 degrees
C.*258*
In Massachusetts Bay, spawning occurs on a falling temperature and begins
at temperatures of 8.3-9.4 degrees C.*258*
The pollock, of all the cod-like fishes, spends less time on bottom and
more time moving freely through the water column than does its
bottom-living relatives. Studies on the Scotian Shelf indicated a broad
overall depth range of 37-364 m and a preferred depth range of 110-181 m.
In the same study the temperature preference was lowest on the northern
part of the shelf, but about 7.2-8.6 degrees C over the remainder of the
shelf. Pollock can withstand temperatures as low as 0 degrees C but
obviously prefer higher temperatures, although they are generally not found
in temperatures above 15.5-18.3 degrees C.*258*
COMMENTS ON ADULT ENVIRONMENTAL ASSOC_ -
The pollock, of all the cod-like fishes, spends less time on bottom and
more time moving freely through the water column than does its
bottom-living relatives. Studies on the Scotian Shelf indicated a broad
overall depth range of 37-364 m and a preferred depth range of 110-181 m.
In the same study the temperature preference was lowest on the northern
part of the shelf, but about 7.2-8.6 degrees C over the remainder of the
shelf. Pollock can withstand temperatures as low as 0 degrees C but
obviously prefer higher temperatures, although they are generally not found
in temperatures above 15.5-18.3 degrees C.*258*
Environment Associations - 1 (DRAFT) - Environment Associations
Species pollock
Species Id M010599
Date 26 AUG 96
COMMENTS ON BREEDING ADULT ENVIRONMENTAL ASSOC_ -
In Massachusetts Bay, spawning occurs on a falling temperature and begins
at temperatures of 8.3-9.4 degrees C.*258*
COMMENTS ON EGG ENVIRONMENTAL ASSOC_ -
Pollock eggs hatch in about 9 d at 6 degrees C and 6 d at 9.5 degrees
C.*258*
Environment Associations - 2 (DRAFT) - Life History
Species pollock
Species Id M010599
Date 26 AUG 96
LIFE HISTORY
MORPHOLOGY/DESCRIPTION: Body fusiform, elongate, laterally compressed.
Head moderate; snout pointed; mouth moderate, lower jaw projecting; small,
equal teeth in jaws; small barbel on lower jaw (chin) of young, becoming
minute and apparently absent in older fish; eye relatively small. Gill
rakers 35-40. Branchiostegals 7. Fins: dorsals, 3, first of 12-14 rays,
second 21-23, third 19-22, all distinctly separate; caudal distinctly but
shallowly forked; anals, 2, first of 24-32 rays, second 20-24; pelvics
small, in advance of pectorals, second ray slightly prolonged; pectorals
relatively small, high on sides. Scales small, cycloid. Lateral line
distinct, complete, more or less straight, not noticeably arched over
pectoral fin, light in color. Vertebrae 53-56. Size, average weight of
2.2-4.5 kg but not usually over 6.8 kg and 91.4 cm long. Color brownish
green above, paling to yellowish, smokey gray or green on sides and silvery
gray on belly; lateral line white to gray; dorsal, caudal, anal, and
pectoral fins olive, but pelvic fins light with reddish tinge. Young
immature pollock lighter overall.*258*
REPRODUCTION: Spawning occurs from November to February in Massachusetts
Bay, Gulf of Maine. Evidence suggests spawning occurs on the Scotian Shelf
and off Cape Breton. The collection of planktonic eggs in March, September,
and November confirms researchers' beliefs that spawning occurred off Nova
Scotia, and extends the spawning period to include September and March in
Canadian waters. There is still no evidence to suggest that spawning
occurs in the Bay of Fundy. The differential distribution of larval pollock
in the Bay of Fundy has led researchers to conclude that pollock spawned
outside the bay.*258*
In Massachusetts Bay, spawning occurs on a falling temperature and begins at
temperatures of 8.3-9.4 degrees C. In European waters spawning occurs at
depths of 100-200 m, not as deep as the 175-275 m for ripening fish reported
off Cape Breton.*258*
An average female may produce 225,000 eggs, but a large female weighing
10.7 kg produced over 4 million eggs. The eggs are spherical, buoyant, and
without an oil globule and are 1.04-1.20 mm in diameter. These pelagic eggs
hatch in about 9 d at 6 degrees C and 6 d at 9.5 degrees C.*258*
GROWTH: Larvae are 3-4 mm long on hatching. Growth is fairly rapid. The
growth rate for pollock in the Bay of Fundy was calculated by researchers
who determined the age from otoliths.*258*
Pollock up to 84 cm FL and 70 kg in weight and up to 14 yr in age were
reported; the species is said to reach a length of up to 107 cm and a weight
of 27-32 kg. The all-tackle world record given by the International Game
Fish Association was 21.06 kg for a fish caught off New Jersey in 1975.*258*
Age (yr) Mean FL (cm)
1 21
2 38
3 44
4 54
Life History - 1 (DRAFT) - Life History
Species pollock
Species Id M010599
Date 26 AUG 96
5 61
6 69
In a 1963 study, males matured at 4-7 yr and 50-65 cm length. However,
length at maturity has declined in recent years for both males and females.
During 1975-79 median total length for males was 46 cm and for females to
about 50 cm and median age at maturity about 3.2 yr for both sexes. Mean
length of the commercial catch from all regions has also declined since 1965. For the Browns Bank region the mean size has dropped from 64.8 cm in 1965-69 to 60.2 cm in 1975-79. Simil,arrly the mean age has dropped to 4.9 yr over the same period. The reasons for these changes are not known but commercial exploitation or changing temperatures or both may be involved.*258*
PREDATION AND COMPETITION: Pollock appear to have few enemies. Pelagic
larval pollock probably fall prey to many predators but no reports have been
published. Some cannibalism has been noted. Adult pollock are eaten
occasionally by harbor seals.*258*
Pollock and silver hake eat similar foods and thus are competitors.*258*
PARASITES AND DISEASE: Helminth parasites of the alimentary tract were
studied by researchers who found 11 species as follows: trematodes (6),
nematodes (2), cestodes (2), and acanthocephalan (1). Trematodes were the
most common, especially Hemiuris levinseni. Anisakine nematodes and the
acanthocephalan Echinorhynchus gadi were next most common. Findings
indicated different levels of infection in pollock from the central Scotian
Shelf region, compared with pollock from the southwestern section,
suggesting separate populations of pollock in the two regions.*258*
In a review of parasites of pollock researchers listed 10 species or species
groups: one protozoan, one monogeneid, two trematodes, one nematode, one
acanthocephalan, and four copepods.*258*
A light infection by blood parasites was detected in specimens from the
Labrador-Newfoundland area.*258*
LIFE HISTORY CODES -
Breeding/Spawning Season: January
Breeding/Spawning Season: February
Breeding/Spawning Season: March
Breeding/Spawning Season: September
Breeding/Spawning Season: October
Breeding/Spawning Season: November
Breeding/Spawning Season: December
Display Site: Water
Average Number of Offspring/Reproductive Effort: Grea
REFERENCES FOR LIFE HISTORY- 258
Life History - 2 (DRAFT) - Management Practices
Species pollock
Species Id M010599
Date 26 AUG 96
MANAGEMENT PRACTICES
Management Practices - 1 (DRAFT) - References
Species pollock
Species Id M010599
Date 26 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