(DRAFT) - Taxonomy
Species porbeagle
Species Id M010730
Date 26 AUG 96
TAXONOMY
NAME - porbeagle
OTHER COMMON NAMES - Mackerel shark and Fr: maraiche
ELEMENT CODE -
CATEGORY - Fish
PHYLUM AND SUBPHYLUM - ,
CLASS AND SUBCLASS - Chondrichthyes,
ORDER AND SUBORDER - Squaliformes,
FAMILY AND SUBFAMILY - Lamnidae,
GENUS AND SUBGENUS - Lamna,
SPECIES AND SSP - nasus,
SCIENTIFIC NAME - Lamna nasus
AUTHORITY - Bonnaterre, 1788
TAXONOMY REFERENCES - 258
Taxonomy - 1 (DRAFT) - Status
Species porbeagle
Species Id M010730
Date 26 AUG 96
STATUS
Coded Status
Commercial/consumption
Commercial/industrial
See Comments
REFERENCES FOR STATUS - 258
COMMENTS ON STATUS -
There is no directed fishery in Canadian waters at the present time although
there was a longline fishery for porbeagle before the discovery of high
mercury levels in shark muscles in 1970 and the cessation of the fishery.
Elsewhere within their range, porbeagle are caught by longlines and sold
fresh and salted for food, the liver for oil, and the carcass for fish meal.
Porbeagle caught incidentally in Canadian waters in weirs or gill nets or on
longlines are sometimes shipped to United States markets, where they are
used for human food and sold in specialty restaurants as shark, mackerel
shark, or mako. The flesh is dense and not unlike that of swordfish in
texture *258*.
Status - 1 (DRAFT) - Distribution
Species porbeagle
Species Id M010730
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 -
A pelagic, epipelagic, or littoral shark usually more common on continental
shelves but occurring sometimes well offshore; also known to frequent
inshore areas, including harbors. More common in the Canadian region
during the spring, summer, and fall but occasionally caught on fishing
banks during winter months. It seems to prefer cool rather than cold
waters, is usually found in temperatures below 16 oC, and has been caught
in temperatures as low as 6 oC in European waters *258*.
ANIMAL/PLANT SPECIES ASSOCIATIONS -
Phyllobothrium dagnallium
Dinobothrium sp.
REFERENCES FOR SPECIES ASSOCIATIONS - 258
COMMENTS ON SPECIES ASSOCIATIONS -
Predation and competition: The porbeagle appears to have few enemies other
than man *258*.
Parasites and disease: There are few records of parasites from porbeagle
caught in the western North Atlantic. A study found Phyllobothrium
dagnallium in stomach, intestine, and spiral valve, and Dinobothrium sp.
from specimens caught around the Magdalen Islands in the Gulf of St.
Lawrence *258*
Habitat Associations - 1 (DRAFT) - Food Habits
Species porbeagle
Species Id M010730
Date 26 AUG 96
FOOD HABITS
TROPHIC LEVEL -
CARNIVORE
REFERENCES FOR TROPHIC LEVEL - 258
LIFESTAGE FOOD FOOD PART
General Clupeiformes Not Specified
General Perciformes Not Specified
General Gadiformes Not Specified
General Squid, Octopus Not Specified
General Osteichthyes Not Specified
REFERENCES FOR GENERAL FOOD - 258
COMMENTS ON FOOD -
The porbeagle is said to feed mainly on small pelagic schooling species such
as herring, gaspereau, and mackerels but cod, white hake, red hake, haddock,
cusk, and squid are also eaten. Detailed food studies have not been
conducted in Canadian Atlantic waters but examination of stomachs of a few
individuals in the Bay of Fundy - Gulf of Maine showed that herring,
gaspereau, mackerel, redfish, and squid were eaten *258*.
Food Habits - 1 (DRAFT) - Environment Associations
Species porbeagle
Species Id M010730
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
G Aquatic Habitat Zonation: Open water [pelagic zone]
G Aquatic Habitat Zonation: Specified in Comments
G Aquatic Habitat Zonation: Shallows with emergent vegetation [littoral zone]
G Coastal Features: Specified in Comments
G Human Association: Specified in Comments
G Water Temperature: Between 15-21 degrees C
G Water Temperature: Below 15 degrees C
G Water Temperature: Specified in Comments
REFERENCES FOR ENVIRONMENTAL ASSOC_ - 258
COMMENTS ON ENVIRONMENTAL ASSOCIATIONS -
A pelagic, epipelagic, or littoral shark usually more common on continental
shelves but occurring sometimes well offshore; also known to frequent
inshore areas, including harbors. More common in the Canadian region
during the spring, summer, and fall but occasionally caught on fishing
banks during winter months. It seems to prefer cool rather than cold
waters, is usually found in temperatures below 16 oC, and has been caught
in temperatures as low as 6 oC in European waters *258*.
Environment Associations - 1 (DRAFT) - Life History
Species porbeagle
Species Id M010730
Date 26 AUG 96
LIFE HISTORY
Reproduction: The porbeagle is ovoviviparous, the developing young being
retained within the brood chamber (oviduct) of the female. The young
cannibalize fertilized eggs in the oviduct and grow large with noticeable
expanded abdomens and branchial regions. The young, 60-75 cm long, are born
alive, 1-5 pups per female, usually in late summer in northwest Atlantic
waters although females with young may be found throughout the year *258*.
Growth: There is little information on rate of growth. Porbeagles are
thought to reach sexual maturity at about 5 yr or older and to have a life
expectancy of about 20-30 yr. Age determinations are considered possible by
counting growth rings on vertebral centra. Of 59 specimens caught off
Georges and Browns banks and Trinity Ledges, NS, males averaged about 1.5 m
TL and females 1.63 m TL. Round weights of 41 specimens ranged from 17 to
156 kg and averaged 75 kg. Dressed weights of 17 individuals averaged 68
percent of round weights. Maximum size to about 3.05 m but usually
1.83-2.44 m. The all-tackle world record by rod and line was of one
weighing 210.92 kg caught off Cornwall, England *258*.
Description: Body spindle-shaped, rather heavy, greatest depth at dorsal
fin; caudal peduncle slender, flattened, with distinct lateral keels and
short secondary keels at caudal base; precaudal pits present. Head stout;
snout pointed; mouth moderate to large; teeth similar in upper and lower
jaws with large central cusp and two lateral cusps, lateral cusps often not
evident on specimens less than 1.2 m long, 24-32 tooth rows in upper jaw,
20-26 in lower jaw; eye large; pectoral origin behind fifth gill slit; gill
slits large. Fins: dorsals, 2, first relatively large, second quite small,
located over anal; caudal nearly symmetrical, ventral lobe well developed
and only slightly smaller than dorsal lobe; anal small, same size as second
dorsal; pelvics small; pectorals large, twice as long as broad. Porbeagles
have heat-regulating mechanisms (heat exchangers) that raise body
temperatures 2.7-8.3 oC above ambient temperatures, allowing them to operate
more efficiently in cool water. Size possibly to 3.05 m long but usually
1.83-2.44 m. Color dark bluish gray to bluish black above, white tip on
lower trailing edge of first dorsal, lower surfaces of pectoral dark on
outer half, mottled white and black toward bases; belly white, unblotched
*258*.
Predation and competition: The porbeagle appears to have few enemies other
than man *258*.
Parasites and disease: There are few records of parasites from porbeagle
caught in the western North Atlantic. A study found Phyllobothrium
dagnallium in stomach, intestine, and spiral valve, and Dinobothrium sp.
from specimens caught around the Magdalen Islands in the Gulf of St.
Lawrence *258*
LIFE HISTORY CODES -
Average Number of Offspring/Reproductive Effort: 1
Average Number of Offspring/Reproductive Effort: 2
Average Number of Offspring/Reproductive Effort: 3-4
Average Number of Offspring/Reproductive Effort: 5-7
Life History - 1 (DRAFT) - Life History
Species porbeagle
Species Id M010730
Date 26 AUG 96
LIFE HISTORY CODES -
Breeding/Spawning Season: July
Breeding/Spawning Season: August
Breeding/Spawning Season: September
REFERENCES FOR LIFE HISTORY- 258
Life History - 2 (DRAFT) - Management Practices
Species porbeagle
Species Id M010730
Date 26 AUG 96
MANAGEMENT PRACTICES
Management Practices - 1 (DRAFT) - References
Species porbeagle
Species Id M010730
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