(DRAFT) - Taxonomy
Species shrimp, pink
Species Id M070008
Date 26 AUG 96
TAXONOMY
NAME - shrimp, pink
OTHER COMMON NAMES - pink shrimp, spotted shrimp, pink-spotted shrimp, brown-spotted shrimp, grooved shrimp, green shrimp, pink-night shrimp, red shrimp, hopper, skipper and pushed shrimp
ELEMENT CODE -
CATEGORY - Aquatic Crustaceans
PHYLUM AND SUBPHYLUM - ,
CLASS AND SUBCLASS - Crustacea,
ORDER AND SUBORDER - Decapoda,
FAMILY AND SUBFAMILY - Penaeidae,
GENUS AND SUBGENUS - Penaeus,
SPECIES AND SSP - duorarum, duorarum
SCIENTIFIC NAME - Penaeus duorarum duorarum
AUTHORITY - Burkenroad, 1939
TAXONOMY REFERENCES - 51
Taxonomy - 1 (DRAFT) - Status
Species shrimp, pink
Species Id M070008
Date 26 AUG 96
STATUS
Coded Status
Commercial/consumption
Commercial/bait
Sensitive
REFERENCES FOR STATUS - 51
COMMENTS ON STATUS -
The pink shrimp fishery is the most economically important of all fisheries
in Florida. More than 17 million pounds of pink shrimp (heads off) were
landed at Florida ports in 1981, providing a total exvessel value of over
$45 million. The pink shrimp catch constituted 26% of the total dollar
value derived from Florida's commercial fisheries. Additional monetary value
can be credited to pink shrimp taken in the extensive bait-fishing
operations along both coasts of Florida.
Pink shrimp is also an important link in marine food chains. Its life
cycle, distribution, and large biomass render the species vulnerable to
diverse predators, many of them commercially or recreationally important
species themselves. The over-harvest of pink shrimp would precipitate a
decline in the abundance of the species. Hypothetically, such a decrease in
biomass could, in turn, negatively affect the predatory species, thus
altering the balance of the whole ecosystem.
Refined and crude oil have been reported to be highly toxic to shrimp.*51*
Status - 1 (DRAFT) - Distribution
Species shrimp, pink
Species Id M070008
Date 26 AUG 96
DISTRIBUTION
Distribution - 1 HABITAT ASSOCIATIONS
NATIONAL WETLAND INVENTORY CODES
NWI NWICLS NWIMOD NWISPEC
Estuarine AB.
Marine
REFERENCES FOR NWI - 51
COMMENTS ON HABITAT ASSOCIATIONS -
-see C.Aquat.Hab
Habitat Associations - 1 (DRAFT) - Food Habits
Species shrimp, pink
Species Id M070008
Date 26 AUG 96
FOOD HABITS
TROPHIC LEVEL -
OMNIVORE
REFERENCES FOR TROPHIC LEVEL - 51
LIFESTAGE FOOD FOOD PART
Larva Microorganisms Not Applicable
Juvenile Polychaetes Not Specified
Juvenile Ostracods Not Specified
Juvenile Copepods Not Specified
Juvenile Malacostraca Not Specified
Adult Squid, Octopus Not Specified
Adult Annelids Not Specified
General Crustaceans Not Specified
General Detritus - Organic Not Applicable
General Molluscs Not Specified
REFERENCES FOR GENERAL FOOD - 51
REFERENCES FOR ADULT FOOD - 51
REFERENCES FOR JUVENILE FOOD - 51
REFERENCES FOR LARVAE FOOD - 51
COMMENTS ON FOOD -
Pink shrimp function as omnivorous consumers (predators) in estuarine and
marine ecosystems, preferring benthic prey. The food habits of the
predatory pink shrimp change as it progresses through the various stages of
its life cycle. Laboratory-reared larvae feed on microplankton; advanced
larvae and postlarvae feed on nauplii as well as microplankton cultures. In
Tampa Bay, the diet of juvenile pink shrimp included dinoflagellates,
foraminiferans, nematodes, polychaetes, ostracods, copepods, mysids,
isopods, amphipods, caridean shrimps, caridean eggs, and mollusks; sand,
debris, algae, diatoms, seagrass, and fish scales have also been found in
shrimp digestive tracts. Although food habits of adult pink shrimp are not
known in detail, in one study stomachs of young adult and adult pink shrimp
in North Carolina estuaries contained foraminiferans, gastropod shells,
squid, annelids, crustaceans, small fishes, plant material, and debris.*51*
COMMENTS ON ADULT FOOD -
Although food habits of adult pink shrimp are not known in detail, in
one study stomachs of young adult and adult pink shrimp in North Carolina
estuaries contained foraminiferans, gastropod shells, squid, annelids,
crustaceans, small fishes, plant material, and debris.*51*
COMMENTS ON JUVENILE FOOD -
Larvae and postlarvae feed on nauplii as well as microplankton cultures. In
Tampa Bay, the diet of juvenile pink shrimp included dinoflagellates,
foraminiferans, nematodes, polychaetes, ostracods, copepods, mysids,
Food Habits - 1 (DRAFT) - Food Habits
Species shrimp, pink
Species Id M070008
Date 26 AUG 96
isopods, amphipods, caridean shrimps, caridean eggs, and mollusks; sand,
debris, algae, diatoms, seagrass, and fish scales have also been found in
shrimp digestive tracts.*51*
COMMENTS ON LARVAE FOOD -
Larvae and postlarvae feed on nauplii as well as microplankton cultures.*51*
Food Habits - 2 (DRAFT) - Environment Associations
Species shrimp, pink
Species Id M070008
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 Bottom Type [Aquatic]: Mud or silt
G Bottom Type [Aquatic]: Sand
G Bottom Type [Aquatic]: Specified in Comments
G Water Temperature: Specified in Comments
G
G Flow: Specified in Comments
LIM Turbidity: Specified in Comments
LIM Bottom Type [Aquatic]: Rooted aquatic vegetation
BA Water Temperature: Between 21-27 degrees C
BA Water Temperature: Between 15-21 degrees C
BA Water Temperature: Below 15 degrees C
REFERENCES FOR ENVIRONMENTAL ASSOC_ - 51
REFERENCES FOR LIMITING ENVIRONMENTAL ASSOC_ - 51
REFERENCES FOR BREEDING ADULT ENVIRONMENTAL ASSOC_ - 188
COMMENTS ON ENVIRONMENTAL ASSOCIATIONS -
Temperature:
Tolerance of pink shrimp to water temperature varies with latitude. Pink
shrimp have been collected from Florida waters at temperatures ranging from
10 to 35.5 degrees C.; they become narcotized at 13.3 degrees C. However,
in estuarine areas of North Carolina, juvenile pink shrimp have been
collected in water temperatures between 4 and 34 degrees C.
Mortalities due to low water temperatures have not been reported in the
warmest part of the species range. Juvenile pink shrimp are sensitive to
low water temperatures in shallow-water environments, and, consequently,
move to deeper (warmer) water at the onset of the cold weather. When
shallow waters warm, the shrimp return to this habitat, unless they have
attained the size for emigration to offshore grounds. In the coldest part
of their range, i.e., estuarine areas of North Carolina, extremely cold
winters may cause many pink shrimp to die. Total mortality in a live bait
tank was observed at a water temperature of 12 degrees C.*51*
Salinity:
Pink shrimp exhibit different degrees of preference to salinity at
different stages of their life cycle. Tidal transport of postlarvae may be
initiated by increases in salinities of flood tides. One study reported
Environment Associations - 1 (DRAFT) - Environment Associations
Species shrimp, pink
Species Id M070008
Date 26 AUG 96
that juveniles exhibit a preference for salinities of 20 ppt or more. As
they grow, they move into deeper, saltier water, until finally they leave
the bays and enter the open sea. In another study, the greatest biomass of
pink shrimp along the gulf coast was distributed around the South Florida
islands, where the salinities are oceanic. Other research found postlarvae
at salinities from 12 to 43 ppt, juveniles from 5 to 47 ppt, and adults
from 25 to 45 ppt in Florida Bay. Adult pink shrimp have been found on the
Tortugas grounds at salinities from 36.2 to 37.7 ppt.
Temperature and Salinity:
Interactions between water temperature and salinity impose strict
environmental restraints on shrimp populations. At low termperatures, all
shrimp have difficulty adjusting to changes in salinity; survival rates
are higher at moderate to high salinities under conditions of low water
temperatures. Pink shrimp have osmoregulatory capabilities superior to
those of brown shrimp at low water temperatures, and thus exhibit a greater
capability for overwintering in estuaries in the northern part of their
range.*51*
Bottom type:
Pink shrimp are associated with shell sand, sand, coral-mud, or mud
bottoms. Subadults prefer shell sand and loose peat; adults prefer
calcareous sediments, but are found also on hard sand bottoms, particularly
in non-turbid waters. Another study found that both white and brown shrimp
preferred soft, muddy bottoms.*188*
Pink shrimp dispersion in nursery areas may be limited by the geographical
distribution of sea-grasses within estuaries. Inshore fisheries do not
occur in areas where seagrasses are rare or absent. Turtle grass
(Thalassia testudium) provides not only cover for shrimp but also suitable
habitat for shrimp food species. High densities of shrimp populations have
been reported where the seagrasses, Diplanthera wrightii and Zostera
marina, were present. Decomposing forest litter has also been found to
constitute a suitable habitat for shrimp in nursery areas of North
Carolina.
Turbidity:
Turtle grass was practically eliminated from sections of Apalachee Bay,
Florida, because of decreased light penetration resulting from turbidity
and coloring of the water by kraft-mill effluents; the most heavily
polluted areas were, in fact, totally without rooted macrophytes. The
unpolluted parts of Apalachee Bay had stable invertebrate populations,
whereas the polluted parts of the estuary had less than half of the number
of invertebrates. The difference was attributed to the reduction in
seagrass biomass in the polluted parts of the bay. Similarly,
dredge-and-fill operations in Tampa Bay have degraded the seagrass beds
that serve as shrimp nursery areas.*51*
Water Movement:
The migration patterns and geographical distribution of shrimp may be
controlled to a large extent by currents. Postlarvae rely on inflowing
currents to move into estuaries. In experimental tank studies, juvenile
pink shrimp showed a positive rheotaxis, which gave way to active
downstream swimming when salinity decreased. Juveniles were reported to
Environment Associations - 2 (DRAFT) - Environment Associations
Species shrimp, pink
Species Id M070008
Date 26 AUG 96
move offshore on ebbing currents. In some south Florida bays, jveniles may
move on each tidal change.
Adult pink shrimp are also positively rheotactic; this orientation to the
water current may be a mechanical response, and may also be the result of
optic fixation.*51*
Light:
Light is an important factor in controlling activity of shrimp. Pink
shrimp remain buried during daylight, emerge from the substrate at sunset,
and become active at night. In laboratory studies, adult pink shrimp tend
to burrow in the presence of solar light; they become active when light
intensity diminishes to less than 0.01076 lumens per m2. Shrimp exhibit
nocturnal activity when exposed to constant low-light conditions for
several days; this persistent pattern of nocturnal activity evinced a
rhythmic control of burrowing and emergence activities.*51*
Oxygen:
Although oxygen requirements of pink shrimp are not known in detail, one
study indicates that oxygen consumption in pink shrimp follows a rhythmic
pattern that coincides with the tidal cycle. Another demonstrated that
oxygen consumption of brown shrimp increased with increases in ambient
temperatures.*51*
COMMENTS ON RESTING ADULT ENVIRONMENTAL ASSOC_ -
Pink shrimp were observed to bury during daylight and were attracted to the
coarse, sand-shell substrate.*188*
COMMENTS ON FEEDING ADULT ENVIRONTAL ASSOC_ -
Juvenile and adult penaeids are omnivorous bottom feeders with food
ingestion occurring largely at night, although, in turbid waters daytime
feeding may occur.*188*
Environment Associations - 3 (DRAFT) - Life History
Species shrimp, pink
Species Id M070008
Date 26 AUG 96
LIFE HISTORY
Morphological Characteristics:
Integument thin, polished, translucent. Carapace with a median carina
continuous anteriorly with rostrum and extending nearly to posterior border
of carapace, flanked on each side by a broad, rounded groove; posterior
half of carina with a median longitudinal groove; anterior half arcuate,
highest above orbit and with 9 or 10 sharp teeth; posterior tooth remote
from others, anterior 6 or 7 on rostrum proper. Lower margin of rostrum
(with) two to three teeth (occasionally one); tip slender, horizontal or
directed slightly downward, unarmed. Anterior margin of carapace with
strong antennal spine on carina extending backward nearly to well-developed
hepatic spine. Cervical groove extending halfway from hepatic spine to
dorsal carina. A sub-horizontal suture below hepatic spine, and a groove
extending from near hepatic spine to near base of ocular peduncle.
Anorbital ridge behind eye.
Female with thelycum composed of two broad lateral plates, and a median
plate. Posteromedian part of median plate of adult with a well-developed,
short, longitudinal carina extending anteriorly toward roughly semicircular,
concave anterior portion. Lateral plates produced medially to meet in
midline, except variably divergent at anteromedian corners, thus exposing
carina of median plates.
Abdomen with segments four to six carinate, carina of sixth ending
posteriorly in a spine and flanked on each side by a narrow groove. Telson
with deep median groove and an acuminate tip. Petasma of male with distal
ends of distoventral lobes curved medially, not projecting free of
distolateral lobes; external edge of distoventral lobes with a series of 2
to 12, usually 4 to 7, small spinules; median or attached edge of
distoventral lobes with a compact group of 5 to 16 large, long, sharp,
curved spines; fold of distolateral lobe rather small and armed
inconspicuously if at all.*51*
Color and Pigmentation:
Color and pigmantation varies mainly with locality and age. In coastal
Florida and on the Tortugas grounds, shrimp colors range from deep pink and
reddish to gray and brown. Juveniles and young adults near coastal areas
and estuaries are gray or reddish-brown. Adults from offshore waters range
in color from red to pink to nearly white. An abdominal spot (gray, blue,
purple, red, or brown) is usually present at pleural juncture of third and
fourth abdominal segments. *51*
Size:
Large males commonly reach about 170 mm total length (TL), and large females
210 mm TL. Specimens have been reported as large as 230 mm TL.*51*
Morphological Differences Among Related Species:
Morphological differences among the three related species of shrimp, pink,
brown (Penaeus aztecus), and white (P. setiferus), are as follows:
Pink: Dorso-lateral grooves on last abdominal segment porminent and narrow;
spot on juncture of third and fourth abdominal segments usually present.
Brown: Adrostral and postrostral crests long, extending almost to the
Life History - 1 (DRAFT) - Life History
Species shrimp, pink
Species Id M070008
Date 26 AUG 96
posterior margin of carapace; gastro-frontal crests present; dorso-lateral
grooves on last abdominal segment well-defined and broad; spot on juncture
of third and fourth abdominal segment usually absent.
White: Length of adrostral grooves less than length of anterior half of
carapace; postrostral crests poorly defined posteriorly and gastrofrontal
crests absent.
Although all three species are found in Florida waters, the pink shrimp is
by far the most prevalent species. The principal populations of brown and
white shrimp are found off the Louisiana and Texas coasts, respectively.*51*
Sexual Maturity:
Females and males attain sexual maturity at 85 and 74 mm TL, respectively.
Ripe females exhibit turgid and enlarged ovaries, with peripheral rod-like
bodies in the ova; females may spawn more than once during their life.
Mature males exhibit joined endopods, and spermatophores with
spermatozoa.*51*
Spawning:
Pink shrimp emigrate from shallow, coastal nursery grounds to deeper
offshore waters in the late juvenile or early adult stage. Spawning occurs
in oceanic waters at depths of 4 to 48 m (12 to 156 ft), and probably in
deeper waters also. It has also been reported that the depth of intensive
spawning activity of Tampa Bay, Florida varied from one year to the
next. Large pink shrimp were reported in water up to 32.9 m offshore of
North Carolina in winter.*188*
The species spawns throughout the year on the Tortugas Shelf at water depths
between 15 and 48 m (49 and 157 ft). In late fall and winter, spawning
activity shifts from shallow to deep water (within those depths where
spawning takes place); this shift may be due to the movement of adult
shrimp to deep waters when temperatures of shallow waters decrease. Larvae
are more abundant during spring, summer and fall than during winter,
indicating some seasonality of reproduction. Spawning of the Tortugas
fishing grounds occurs mainly during the last phase of the lunar month.
Rising temperatures have been found to be an important factor in triggering
spawning, which occurs principally at water temperatures between 19.6 and
30.6 degrees C. The peak in spawning activity generally coincides with
maximum bottom-water temperatures.
The eggs, approximately 0.23 to 0.33 mm in diameter, are demersal.
Coloration is generally an opaque yellow-brown, but the chorion may appear
bluish under certain light reflections. Eggs of pink shrimp spawned in the
laboratory were visible to the naked eye and appeared like fine, white
powder. The number of eggs produced per spawn is unknown, but a 172-mm TL
white shrimp contained 860,000.*51*
Larvae:
Laboratory-reared larvae exhibited five naupliar stages, three protozoeal
stages, and two to five mysis stages. Under laboratory conditions, the
duration of the larval development was 15 days in 26 degree C water and 21
days in 21 degree C water; shrimp underwent fewer mysis stages in the 26
degree C water than in the 21 degree C water.
The pelagic larvae are carried into the Florida Current from the Tortugas
Life History - 2 (DRAFT) - Life History
Species shrimp, pink
Species Id M070008
Date 26 AUG 96
grounds by westerly and southwesterly currents; the Florida Current, in
turn, transports the larvae to the nursery grounds in Everglades National
Park. Larvae may use tidal currents to enter the estuarine nursery
grounds.*51*
Postlarvae:
Postlarvae enter estuarine and coastal bay nursery areas at 8 mm TL. Peaks
of abundance occur in spring and late fall. The abundance of immigrating
postlarvae increases with increasing velocity of flood tides. Postlarvae
become benthic at about 10 mm TL, and concentrate where habitat offering
shelter is adequate.*51*
Juveniles and Adults:
Pink shrimp spend from 2 to 6 months in nursery areas. Activity patterns
that may take place while shrimp remain in nursery areas have been observed
under laboratory conditions: (1) a bimodal pattern of diurnal burrowing
and nocturnal activity in juvenile pink shrimp was observed at full and new
moons, and (2) the timing of nocturnal activity peaks corresponded with the
normal tide progression in the area where the shrimp were captured. The
researcher believed a circadian rhythm was responsible for the nocturnal
activity because it repeated itself under constant light conditions.
Another study indicated that burrowing was influenced also by type of
substrate and lunar phase. Thus, activity patterns of pink shrimp in
nurseries are probably a product of circadian rhythms and
rhythmically-occurring environmental stimuli.*51*
Emigration occurs year-round with a principal peak during fall and a lesser
one during spring.
The greatest concentrations of adult shrimp are found between 9 and 44 m
although some specimens have been found in Florida waters at depths of 110
m.*51*
Growth and Mortality:
The growth rate of pink shrimp differs among the different stages of its
life cycle; it is influenced also by sex and by water temperature. Growth
has been observed from 0.38 mm TL (nauplii) to 4.1 mm TL (postlarvae) in 2
to 3 weeks. Monthly growth rates for juveniles have been reported ranging
from 7 to 52 mm. Monthly growth rates for sub-adult and adult shrimp are
considerably less, ranging from 0 to 22 mm TL.
The sex ratio of juvenile pink shrimp has been reported as 1:1. However,
others have reported that differences in size of shrimp, geographic area and
season often shifted the sex ratio from 1:1.
Pink shrimp become available to the bait fishery at about 6 weeks of age or
47 mm TL. Sexual maturity is attained at 9 or 10 weeks of age. Pink shrimp
were first recruited into the Tortugas commercial fishery at 15 weeks,
providing a fishable life span of 68 weeks. Although average maximum age
has been indicated as 83 weeks, absolute maximum age may reach or exceed 2
years.
The size composition of landed pink shrimp varies with habitat, season and
time of day. Small and immature shrimp inhabit shallow-water estuarine
areas, whereas mature shrimp emigrate to deep offshore waters. Shrimp
harvested on the Tortugas grounds ranged from 49 to 230 mm TL.
Mortality rates of harvestable shrimp from Florida waters varied
substantially; total mortality coefficients ranged from about 0.10 to
Life History - 3 (DRAFT) - Life History
Species shrimp, pink
Species Id M070008
Date 26 AUG 96
0.36. The relative proportion of total mortality attributable to fishing
mortality varied similarly, ranging broadly between about 30% and 80%.
Bi-weekly rates of fishing mortality were estimated at 6.8% and 13.1% on the
Sanibel and Tortugas grounds, respectively, during the early 1960's. Males
seemingly exhibit higher mortality rates than females.*51*
Foraging:
Pink shrimp function as omnivorous consumers (predators) in estuarine and
marine ecosystems, preferring benthic prey. Juveniles and young adults in
estuarine habitats forage along the bottom in shallow-water grass beds.
Foraging occurs mainly at night, although some takes place during the day,
particularly in turbid water. Seasonally, feeding activity peaks during the
summer.*51*
Predation:
Pink shrimp are a major prey species to a wide variety of fish. Inshore
species, such as snook (Centropomus undecimalis), spotted seatrout
(Cynoscion nebulosus), and mangrove or gray snapper (Lutjanus griseus), feed
heavily on pink shrimp. In one study, 61% of the spotted seatrout in
coastal waters of Texas had eaten shrimp exclusively. Shrimp were the
second most abundant food item taken by snook in southwestern Florida in
another study. Forty-two percent of the mangrove snapper stomachs from
Everglades Park contained pink shrimp.
Reef species, such as mutton snapper (Lutjanus analis), red grouper
(Epinephelus morio), black grouper (Mycteroperca bonaci), and even pelagic
king mackerel (Scomberomorus cavalla), are all predators of pink shrimp.
Pink shrimp have also been found in the stomachs of bottle-nosed dolphins
and striped dolphins.
A variety of birds also utilize shrimp as a food resource to some extent.
Wading birds are opportunistic feeders, and take shrimp in coastal areas.
Seabirds commonly forage in mixed-species flocks to feed on concentrations
of prey. Shrimp, which often congregate when moving through channels and
into and out of estuaries, are probably easy prey for diving seabirds at
these times. Reptiles and aquatic mammals in estuarine habitats also may
prey on shrimp.*51*
Competition:
As competitors, pink shrimp share habitats with both white and brown shrimp.
The three species exhibit different preferences for salinity, temperature,
substrate, and cover. The preferences, in turn, determine maximum densities
of each shrimp species at different times of the year within the same
estuary. Although the exact nature and degree of competition among these
three commercial species of Penaeus is not known, it is reasonable to assume
that the three different species have developed different physiological
requirements, which allow them to occupy different realized niches in
Florida nursery grounds as well as in North Carolina estuaries.
Competition between pink and white shrimp in offshore environments is
probably mitigated by differences in substrate preference, food and
daily-activity cycles.*51*
Diseases:
Pink shrimp are vulnerable to numerous diseases. No disease, however,
exerts an appreciable impact on the commercial pink shrimp fishery. The
Life History - 4 (DRAFT) - Life History
Species shrimp, pink
Species Id M070008
Date 26 AUG 96
whitish discoloration of body tissue, which is referred to as "milk" or
"cotton" shrimp, is more noticeable than other "diseases" of shrimp. The
condition is caused by high levels of microsporidian infection. Commonly
observed blackened areas of the exoskeleton are caused by chitinoverous
bacteria, which attack the edges or tips of exoskeletal parts and cause
internal damage if they are able to enter the body.
Pollutants:
Available evidence indicates that petroleum and other oil products have a
negative impact on penaeid shrimp. Refined and crude oil have been reported
to be highly toxic to shrimp. The presence of petroleum hydrocarbons have
been detected in marine sediment and in the body tissues of pink shrimp and
other penaeid species caught on the Campeche Bank of Mexico.
In one study, pink and brown shrimp were not able to metabolize high
molecular weight hydocarbons (obtained from oil from Kuwait).
These toxic compounds would increase in concentration along the higher
levels of the food chain, attaining their maximum concentration in man.
Diesel fuel is highly toxic to protozoeal and naupliar stages of the shrimp
Penaeus californiensis.*51*
REFERENCES FOR LIFE HISTORY- 51 and 188
Life History - 5 (DRAFT) - Management Practices
Species shrimp, pink
Species Id M070008
Date 26 AUG 96
MANAGEMENT PRACTICES
RESULT MANAGEMENT PRACTICE
Beneficial Regulating commercial harvest levels
Beneficial Maintaining undisturbed/undeveloped areas
Beneficial Maintaining unique or special habitat features [wetlands, caves,
Beneficial Maintaining natural vegetation [native]
Beneficial Developing/maintaining/protecting wetlands
Beneficial Controlling pollution [thermal, chemical, physical]
Beneficial Controlling sedimentation
Adverse Draining wetlands, marshes, ponds, lakes
Adverse Dredging
Adverse Construction of navigational improvements [dams, locks, etc.]
Adverse Constructing/maintaining bulkheads, seawalls, and dikes
Adverse Shoreline modification/development
Adverse Migration barriers
REFERENCES FOR BENEFICIAL MANAGEMENT PRACTICES - 51
REFERENCES FOR ADVERSE MANAGEMENT PRACTICES - 51
COMMENTS ON MANAGEMENT PRACTICES -
Because of its role as predator, prey and competitor, pink shrimp
constitutes an important link in estuarine and marine food chains. Stable
ecosystems are the product of a particular combination of species in
relatively fixed proportions; if one of the species is greatly disturbed,
those ecosystems become unstable. For species not at the top of the trophic
chain, e.g., the pink shrimp, the level of harvest should be below that
which greatly reduces population abundance; consequently, under some
circumstances, predation alone may reduce shrimp populations to
unharvestable levels. Degradation of estuarine habitats may significantly
decrease numbers of pink shrimp. This decrease could affect directly all
the commercial species of fish that rely on the pink shrimp as a major food
resource.*51*
The over-harvest of pink shrimp would precipitate a decline in the
abundance of the species. Hypothetically, such a decrease in biomass could,
in turn, negatively affect the predatory species, thus altering the balance
of the whole ecosystem.*51*
Estuaries and other shallow coastal seagrass communities, which are at risk
of development, are important nursery grounds for the species. Preservation
of these habitats is essential for the development of shrimp through the
early stages of their life cycle, and, consequently, for the continuation of
harvestable shrimp populations.*51*
Adequate stock recruitment of pink shrimp on Florida's fishing grounds may
be at risk in future years if the critically important estuarine-nursery
areas are degraded by the developmental processes associated with the
State's rapidly expanding human population. Inshore fisheries do not occur
in areas where seagrasses are rare or absent. Turtle grass (Thalassia
testudium) provides not only cover for shrimp but also suitable habitat for
shrimp food species. Turtle grass was practically eliminated from sections
of Apalachee Bay, Florida, because of decreased light penetration resulting
Management Practices - 1 (DRAFT) - Management Practices
Species shrimp, pink
Species Id M070008
Date 26 AUG 96
from turbidity and coloring of the water by kraft-mill effluents; the most
heavily polluted areas were, in fact, totally without rooted macrophytes.
The unpolluted parts of Apalachee Bay had stable invertebrate populations,
whereas the polluted parts of the estuary had less than half of the number
of invertebrates. The difference was attributed to the reduction in
seagrass biomass in the polluted parts of the bay. Similarly,
dredge-and-fill operations in Tampa Bay have degraded the seagrass beds that
serve as shrimp nursery areas.*51*
Several shoreline development practices severely degrade shrimp habitat.
The most obvious and highly publicized of these is the flow of polluted
waters into estuaries. Other practices that negatively alter shrimp nursery
habitats include: (1) direct saltwater intrusion (or diversion of natural
freshwater discharge), which causes unfavorable salinity regimes; (2)
impounding of natural waterways, which prevents the influx of immigrating
shrimp; and (3) bulkheading of shorelines, which removes the critical
marsh- or mangrove water interface. In one study 2.5 times as many brown
shrimp and 14 times more white shrimp were found along a natural shoreline
than along a bulkheaded shoreline.*51*
The Fishery:
The fishery for pink shrimp in the United States is concentrated along the
central and southern coastal regions of the Gulf of Mexico. In Florida,
gulf waters yield 99% and Atlantic waters 1% of the total annual landings of
pink shrimp, which, in 1981, exceeded 17 million pounds.
Indications are that pink shrimp are fully recruited into the fishery at 120
mm TL. Recruitment of pink shrimp in the eastern Gulf of Mexico occurs
year-round; the peak of recruitment, however, takes place in fall, with a
secondary peak occurring in spring.
Gear:
Commercial shrimpers use basically the same fishing gear and methods, with
local modifications, throughout the Gulf of Mexico. Vessels range in size
from about 15 to 26 m (50 to 85 ft.). The newer boats have either steel or
fiberglass hulls and are usually diesel powdered. Although some fishermen
still prefer to pack their catch in ice, most now utilize freezers because
of the increased length of fishing trips and ever-rising ice prices.
The standard commercial shrimp net is the otter trawl. These funnel-shaped
nets are weighted along the bottom and have a row of floats along the top to
keep the mouth of the net open. A large, metal-rimmed wooden "otter"board or
trawl "door" is attached to each side or "wing" of the net to help spread
the net. Standard shrimp otter trawls have a spread of about 13.7 m, and
have a mesh size of 45 mm. Most of the trawling for pink shrimp in Florida
waters is conducted at water depths between 7 and 37 m.
Otter trawls are commonly "double rigged," with one net towed from an
outrigger on each side of the vessel. Often, "twin rigs" are used, wherein
two trawls are towed from each side. These rigs are usually fished for 2 to
3 hours at a time. A much smaller "try" net of the same mesh size is fished
concurrently. This net is brought on board much more frequently, and its
contents are used as an estimate of the catch in the larger nets.*51*
Management Practices - 2 (DRAFT) - References
Species shrimp, pink
Species Id M070008
Date 26 AUG 96
References
51* Bielsa, L., W. Murdich, R. Labisky. 1983. Species Profiles: Life
Histories and Environmental Requirements of Coastal Fishes and
Invertebrates (South Florida) -- Pink Shrimp. U.S. Fish and
Wildlife Service Biol. Rep. 82(11.17) pp 21.
188 * South Atlantic Fishery Management Council. 1981. Profile
of the Penaeid Shrimp Fishery in the South Atlantic. (ed.).
South Atlantic Fishery Management Council Charleston, SC:273.
References - 1