(DRAFT) - Taxonomy
Species shrimp, northern
Species Id M070011
Date 26 AUG 96
TAXONOMY
NAME - shrimp, northern
OTHER COMMON NAMES -
ELEMENT CODE -
CATEGORY - Aquatic Crustaceans
PHYLUM AND SUBPHYLUM - ,
CLASS AND SUBCLASS - ,
ORDER AND SUBORDER - Decapoda,
FAMILY AND SUBFAMILY - Padalidae,
GENUS AND SUBGENUS - Pandalus,
SPECIES AND SSP - borealis,
SCIENTIFIC NAME - Pandalus borealis
AUTHORITY - Kroyer
TAXONOMY REFERENCES - 168
Taxonomy - 1 (DRAFT) - Status
Species shrimp, northern
Species Id M070011
Date 26 AUG 96
STATUS
Coded Status
Commercial
Commercial/consumption
Existing, FMP exists
REFERENCES FOR STATUS - 168 and 124
COMMENTS ON STATUS -
The northern shrimp supports an increasingly important commercial fishery in
the western Gulf of Maine.*124*
There is an Interstate Fishery Management Plan for the northern shrimp
fishery in the western Gulf of Maine which was prepared in cooperation with
the Northern Shrimp Technical Committee and the Northern Shrimp Section of
the Atlantic States Marine Fisheries Commission. The plan was reviewed
and amended in 1986.*124*
Overharvesting as occurred in the late 1960s was the major limitation on
shrimp populations. Initially the catch consisted almost exclusively of
egg-bearing females, which are the largest individual of the species and
which inhabit shallower waters. In recent years larger vessels,
improvements in fishing gear, and changes in fishing season have increased
the proportion of males and transitionals in the catch.
Discharges of oil and other contaminants have the potential to affect shrimp
populations. The effect of these factors on shrimp stocks is unknown.*168*
Status - 1 (DRAFT) - Distribution
Species shrimp, northern
Species Id M070011
Date 26 AUG 96
DISTRIBUTION
Distribution - 1 HABITAT ASSOCIATIONS
NATIONAL WETLAND INVENTORY CODES
NWI NWICLS NWIMOD NWISPEC
Marine UB3
Marine OW0
REFERENCES FOR NWI - 124
Habitat Associations - 1 (DRAFT) - Food Habits
Species shrimp, northern
Species Id M070011
Date 26 AUG 96
FOOD HABITS
TROPHIC LEVEL -
OMNIVORES
REFERENCES FOR TROPHIC LEVEL - 124
LIFESTAGE FOOD FOOD PART
Adult Polychaetes
Adult Echinoderms
Adult Molluscs
Adult Crustaceans
Adult Protozoans
REFERENCES FOR ADULT FOOD - 168
COMMENTS ON FOOD -
Northern shrimp are omnivores, functioning both as predators and scavengers.
Their diet is determined essentially by the prey available, the time of day,
and their developmental stage. In the Gulf of Maine, the winter diet is
predominantly molluscs, while in the summer the bulk of the diet consists of
crustaceans. A variety of finfish and invertebrates prey upon northern
shrimp. Finfish species which feed heavily on pandalid shrimp include four
species of hake (red hake, silver hake, longfin hake, and white hake) and
two species of flounder (fourspot and windowpane flounder). A number of
other finfish also feed on northern shrimp, but not as selectively.*124*
COMMENTS ON ADULT FOOD -
The diet of adult shrimp varies with the season, consisting of a larger
proportion of molluscs in the winter and crustaceans in the summer. The
shrimp may also eat polychaetes, protozoans, and echinoderms.*168*
Food Habits - 1 (DRAFT) - Environment Associations
Species shrimp, northern
Species Id M070011
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 Water Temperature: Below 15 degrees C
G
G Water Depth Preference: 50-100 ft.
G Water Depth Preference: 100-200 ft.
G Water Depth Preference: 200-500 ft.
G Substrate: Mud or silt
REFERENCES FOR ENVIRONMENTAL ASSOC_ - 124
COMMENTS ON ENVIRONMENTAL ASSOCIATIONS -
Throughout their range, northern shrimp have been reported in waters with
temperatures of -1.6 to 12.1 degrees C, but are most common at temperatures
of zero to 5 degrees C. Extended exposure to temperatures below -1 degrees
C have been observed to cause mass mortalities. They prefer waters of
fairly high salinity, although the species has been reported in salinities
ranging from 23 to 36 ppt. Northern shrimp have been found in depths of 9
to 1,450 m, but are most common from 50 to 500 m, predominantly in soft
mud or sand/silt substrates.*124*
COMMENTS ON LIMITING ENVIRONMENTAL ASSOC_ -
Historical trends in abundance appear to have been strongly influenced by
temperature, with above-normal temperatures being associated with poor
recruitment. *245*
Environment Associations - 1 (DRAFT) - Life History
Species shrimp, northern
Species Id M070011
Date 26 AUG 96
LIFE HISTORY
Northern shrimp are protandric hermaphrodites; that is, individuals
function first as males and then change sex to become females.*124*
Between the ages of 1 and 3 years, most individuals of this species are
sexually mature males. The transition to the female gender may begin as
early as 20 months, although it is more common at 32 months, and by 43
months almost all individuals are functional females. Some females spawn
twice, although most spawn only once in their lifetimes. Estimated normal
life span for individuals of this species in the Gulf of Maine is 4 to 5
years.
In offshore waters of the Gulf of Maine copulation occurs after females
molt. Eggs (330 to 500) are carried on the female's pleopods (appendages on
the underside) through the winter, during which time females migrate
inshore. Egg-bearing shrimp may prefer cold water and therefore in the
winter move gradually inshore, where the waters are cooling. The time of
hatching depends on water temperatures during the winter in which the eggs
are being carried on the female. In warm years hatching may take place as
early as February and most hatching is usually completed by April. After
hatching, larvae are planktonic until they lose their exopods (swimming
appendages) after about three months. Male juveniles remain inshore until
their second winter (end of 2nd year) when they begin to migrate offshore.
In the fall egg-bearing females (end of 4th year) begin their migration
inshore.
PARASITES:
There are 2 known parasites of the northern shrimp. One of these affects
the eggs of the shrimp and has been tentatively identified as a parasitic
dinoflagellate. The affected eggs are no longer viable and fecundity is
reduced. The other organism is a dinoflagellate of the genus Gymnodinioides
and infects the gills of adult shrimp. It is not known if mortalities from
these parasites alter the shrimp population.*168*
Growth Rate:
Northern shrimp which live in sub-actic waters grow more slowly and live
longer than shrimp from southern locations such as the Gulf of Maine.
Shrimp exposed to colder temperatures also mature at more advanced ages.
Northern shrimp in the Gulf of Maine grow rapidly, especially during their
first two years of life, reaching 8 mm carapace length (CL) at age six
months, 16.7 mm CL at 18 months, and 22.4 mm CL at age 30 months; a maximum
size of approximately 32 mm CL is attained by older females. Shrimp grow
more rapidly in the spring and summer than in the winter. Warmer bottom
water temperatures have been associated with more rapid growth and earlier
sex transition in the Gulf of Maine.*124*
LIFE HISTORY CODES -
Average Number of Offspring/Reproductive Effort: 101-
Number of Broods/Litters (Reproductive Efforts) Per Ye
REFERENCES FOR LIFE HISTORY- 168 and 124
Life History - 1 (DRAFT) - Management Practices
Species shrimp, northern
Species Id M070011
Date 26 AUG 96
MANAGEMENT PRACTICES
RESULT MANAGEMENT PRACTICE
Existing Regulating harvest of species being described
Existing Regulating harvest - setting seasons
Existing Regulating commercial harvest gear types
Adverse Harvest of species using non-selective gear
REFERENCES FOR ADVERSE MANAGEMENT PRACTICES - 124
REFERENCES FOR EXISTING MANAGEMENT PRACTICES - 124
COMMENTS ON MANAGEMENT PRACTICES -
The Gulf of Maine northern shrimp fishery is managed through interstate
agreement between the States of Maine, New Hampshire, and
Massachusetts. The distribution of northern shrimp in the western Gulf of
Maine and the seasonal nature of the fishery make it imperative that
northern shrimp management be viewed in the context of overall management of
the Gulf of Maine resource.
Fisheries Interactions:
Since the northern shrimp fishery is conducted primarily by trawling with
small-mesh gear, by-catch and discard of unmarketable finfish would be
expected. Data suggest that incidental mortality to juvenile groundfish in
the Gulf of Maine shrimp fishery and concomitant reductions in yield could
be substantial. There is little documentation on possible impacts of such
discards although it has been shown that discard of small whiting in the
Gulf of Maine shrimp and whiting fisheries can cause significant reductions
in whiting abundance and may have contributed to the general failure of this
stock to recover from low levels of abundance in the early 1970's.
Presumably, incidental mortality on other species, particularly redfish,
various flatfish species, and red and white hake could also be significant.
Attempts to reduce finfish discard in the Gulf of Maine shrimp fishery have
focused on use of shrimp separator trawls (SSTs) designed to retain most of
the shrimp catch while excluding all or most of the finfish.*124*
The potential for by-catch of shrimp in directed finfish fisheries has also
been of concern, particularly during years of low shrimp abundance. There
is little evidence of appreciable by-catch and discard of shrimp in demersal
trawl fisheries with the exception of the whiting fishery. THe whiting
fishery has been of primary interest due to mesh sizes used and areas
fished. Such by-catch could be reduced to insignificant levels by use of 6m
(2.4 inch) stretched mesh trawls.*124*
Measures for regulating harvest of northern shrimp in the Gulf of Maine:
1. Gear limitations: a minimum mesh size of 5-1/2 inches for all trawl
gear used in the Gulf of Maine
2. Seasonal limitations: An open season not to exceed 183 days, will be
set on an annual basis. The fishery shall not begin sooner than December 1
nor end later than May 31 for any one year.
3. Possession limitations: The count per pound for all shrimp landed and
subsequently possessed by fishermen and dealers/processors shall be
Management Practices - 1 (DRAFT) - Management Practices
Species shrimp, northern
Species Id M070011
Date 26 AUG 96
consistent with the selectivity of the minimum mesh size specified
4. Information collection provisions: All primary dealer/processors shall
report periodically their transactions involving northern shrimp.*124*
(See 1986 amended FMP for more detailed information)
Management Practices - 2 (DRAFT) - References
Species shrimp, northern
Species Id M070011
Date 26 AUG 96
References
124* McInnes, D. (ed.). 1986. Interstate Fishery Management Plan for
the Northern Shrimp (Pandalus borealis Kroyer) Fishery in the
Western Gulf of Maine. pp 37.
168* Fefer, Stewart, Patricia Schettig. 1980. An Ecological
Characterization of Coastal Maine. 1-3. Department of the
Interior.
245 * U.S. Department of Commerce. 1989. Status of the Fishery
Resources off the Northeastern United States for 1989. NOAA
Technical Memorandum NEC-72 (ed.). U.S. Department of Commerce
Washington, DC:110.
References - 1