(DRAFT) - Taxonomy
Species crab, stone
Species Id M070007
Date 26 AUG 96
TAXONOMY
NAME - crab, stone
OTHER COMMON NAMES -
ELEMENT CODE -
CATEGORY - Aquatic Crustaceans
PHYLUM AND SUBPHYLUM - ,
CLASS AND SUBCLASS - Malacostraca,
ORDER AND SUBORDER - Decapoda,
FAMILY AND SUBFAMILY - Xanthidae,
GENUS AND SUBGENUS - Menippe,
SPECIES AND SSP - mercenaria,
SCIENTIFIC NAME - Menippe mercenaria
AUTHORITY - Say
TAXONOMY REFERENCES - 49
Taxonomy - 1 (DRAFT) - Status
Species crab, stone
Species Id M070007
Date 26 AUG 96
STATUS
Coded Status
Commercial
Commercial/consumption
REFERENCES FOR STATUS - 49
COMMENTS ON STATUS -
The stone crab is the largest of the xanthid crabs within its range and is
the only one to support a fishery. The claws are harvested for their appeal
as a delicacy with high market value. In Florida the annual stone crab
landings are valued at well over $4 million, placing this species among the
State's top 10 commercially important marine species.*49*
Status - 1 (DRAFT) - Distribution
Species crab, stone
Species Id M070007
Date 26 AUG 96
DISTRIBUTION
Distribution - 1 HABITAT ASSOCIATIONS
NATIONAL WETLAND INVENTORY CODES
NWI NWICLS NWIMOD NWISPEC
Marine UB3
Marine RB.
Marine RS1
Marine UB1
Marine RB1
Marine RB.
Marine RS1
Marine UB1
Marine RB1
Marine UB3
REFERENCES FOR NWI - 49
COMMENTS ON HABITAT ASSOCIATIONS -
Adult stone crabs can be considered eurythermal because they have been
found in ambient temperatures of 8 degrees to 32 degrees C. At the lower
temperatures, however, they were usually inactive and sealed themselves in
burrows, and at the higher temperatures they sought the coolness of deeper
water.
In North Carolina the smallest juvenile stone crabs were found in deep
channels where they lived beneath shell fragments. At a size of about 13
mm CW, small crabs move into shallower water and are found wherever
crevices are abundant: about rocks, jetties, pilings, and in oyster shell
rubble. At Cedar Key, Florida, juveniles less than 1.3 cm are found in
deep channels and in seagrass beds. At a larger size, 3.0 to 5.0 cm, small
crabs are found on oyster bars during the summer in the Cedar Key area.
Researchers reported oyster bars to be a least preferred habitat of stone
crabs, although researchers did find juvenile and adult crabs there.
In the Florida Keys and at Cedar Key, sponges, gorgonians, submerged rock,
and Sargassum mats are commonly used as refuges by juvenile stone crabs.
Offshore from Alligator Harbor, Florida, juveniles were commonly found in
colonies of the bryozoan Schizoporella pungens. Juvenile stone crabs are
believed to be attracted to seagrass beds both by their abundant refugia
and by Thalassia-blade epiflora and epifauna.*49*
Habitat Associations - 1 (DRAFT) - Food Habits
Species crab, stone
Species Id M070007
Date 26 AUG 96
FOOD HABITS
TROPHIC LEVEL -
CARNIVORE
REFERENCES FOR TROPHIC LEVEL - 49
LIFESTAGE FOOD FOOD PART
Larva Crustaceans Not Specified
Larva See Comments; Food
Juvenile See Comments; Food
Adult Molluscs Not Specified
Adult See Comments; Food
REFERENCES FOR GENERAL FOOD - 49
REFERENCES FOR ADULT FOOD - 49
REFERENCES FOR JUVENILE FOOD - 49
REFERENCES FOR LARVAE FOOD - 49
COMMENTS ON ADULT FOOD -
Adult stone crabs can generate tremendous crushing forces with their smaller
chelae or "pincer." The adult stone crabs can exert a pressure on its
rearmost crushing teeth of up to 19,000 lb/inch(squared). The pincer also
has occluding teeth that are used in cutting shell or tissue. These
formidable claws are used to break open shells of numerous types of
mollusks. The larger, or crusher claw, is the most important claw in
feeding because, when the original crusher is removed, the pincer or fast
claw develops, through molting, into a more heavily built replacement
crusher claw.*49*
Adults possess a complex behavioral repertoire. They defend burrows, move
offshore and onshore as previously discussed, court before mating,
stridulate, and employ diverse modes for feeding on several types of
gastropods and bivavles. The behavioral complexity of the Menippe is
demonstrated by the manner in which it opens gastropod shells. The
attacking stone crab first manipulates the prey shell with its two large
claws and its walking legs. The minor claw or pincer may be inserted into
the snail's aperture with a probing motion that may have a chemosensory
function. The crab then positions the shell between the teeth of its
crusher and attempts to crush the spire, the siphonal canal, or the
columellar region. If crushing these areas fails because the snail is large
relative to the crab, the crab may reposition the snail so that the thumb
of the crusher can be inserted into the aperture of the shell. This places
the lip of the shell between the teeth of the crab's claw. The crab then
bends the lip outward, an action which, in juvenile snails, causes the lip
to break. This action, when repeated, "peels" the shell so that either the
fleshy snail parts are exposed or the size of the snail is reduced and may
be grasped for further attempts at crushing.*49*
Food Habits - 1 (DRAFT) - Food Habits
Species crab, stone
Species Id M070007
Date 26 AUG 96
COMMENTS ON JUVENILE FOOD -
The natural diet of juvenile stone crabs is unknown. Researchers reported
that juvenile stone crabs held in captivity ate polychaetes, small bivalves,
oyster drills, and each other. In aquaria, juvenile crabs ate everything
from fish flesh to beef liver and chicken parts.*49*
COMMENTS ON LARVAE FOOD -
Actively feeding larval stages of stone crabs are generally thought to be
almost entirely carnivorous. In laboratory culture they have been sustained
through all larval stages on a diet of brine shrimp nauplii. Researchers
found low survival levels in cultures of stone crab larvae that were fed
only algal cells. Studies showed reduced survival levels in stone crab
larvae maintained on rotifers instead of Artemia. Apparently Menippe larvae
have strict dietary requirements that are met by only certain types of
planktonic animals. No dietary studies of zoeae or megalopae have been
performed, but planktonic larval stages and permanent zooplankton are
probably their preferred prey.
Food Habits - 2 (DRAFT) - Environment Associations
Species crab, stone
Species Id M070007
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
A Water Temperature: Greater than 27 degrees C
A Water Temperature: Between 21-27 degrees C
A Water Temperature: Between 15-21 degrees C
A Water Temperature: Below 15 degrees C
A Water Temperature: Specified in Comments
A
A
A
A
A
A
A
A Dissolved Oxygen: Specified in Comments
A Bottom Type [Aquatic]: Rooted aquatic vegetation
A Aquatic Habitat Zonation: Shallows with emergent vegetation [littoral zone]
J Bottom Type [Aquatic]: Organic debris
J Bottom Type [Aquatic]: Rooted aquatic vegetation
J Relation to Substrate: Specified in Comments
L Water Temperature: Specified in Comments
L
REFERENCES FOR ENVIRONMENTAL ASSOC_ - 49
REFERENCES FOR RESTING ADULT ENVIRONMENTAL ASSOC_ - 49
REFERENCES FOR RESTING JUVENILE ENVIRONMENTAL ASSOC_ - 49
REFERENCES FOR RESTING LARVAE ENVIRONMENTAL ASSOC_ - 49
COMMENTS ON ENVIRONMENTAL ASSOCIATIONS -
Stone crab burrows have been reported from nearshore, shallow-water
Thalassia grassflats and adjacent deeper channels, and researchers noted
the use of sponges, gorgonians, and shell bottom by juveniles. Anecdotal
accounts abound for concentrations of adult stone crabs among crevices of
bridge pilings and artificial reef rubble. These studies and accounts
suggest a fundamental requirement by M. mercenaria for substrate suitable
for refuge, met either by burrowing into consolidated sand-shell mix or by
using available hard cover.*49*
Environment Associations - 1 (DRAFT) - Environment Associations
Species crab, stone
Species Id M070007
Date 26 AUG 96
COMMENTS ON RESTING ADULT ENVIRONMENTAL ASSOC_ -
Adult stone crabs can be considered eurythermal because they have been
found in ambient temperatures of 8 degrees to 32 degrees C. At the lower
temperatures, however, they were usually inactive and sealed themselves in
burrows, and at the higher temperatures they sought the coolness of deeper
water.
Temperature has an apparent effect on the reproduction and development of
stone crabs. Studies have found a significant positive correlation between
the percentage of sample females carrying eggs and the ambient temperature,
across the range of 21 degrees to 30 degrees C in Biscayne Bay. There is
also a correlation between ovarian development and local water temperature,
with an optimum at about 28 degrees C. Similarly, an increase in spawning
during March was noted, when temperatures rose above 22 degrees C, and a
decrease in spawning after the temperature dropped in October. Less than
1% of the females collected were carrying eggs when the water temperature
was below 20 degrees C.
Molting was also favored by the optimal temperature (28 degrees C), but was
inhibited by spawning. The intermolt interval for both juveniles and
adults was shorter at elevated temperatures, although an upper tolerance
limit was not noted.*49*
Salinity. Adult stone crabs can be considered euryhaline although they
are typically found in salinities approaching full seawater. Researchers
reported tolerance of gradual salinity changes, i.e., over 3-week periods,
to a low of 6-7.5 ppt and a high of 40.5 ppt, with no significnat change in
oxygen consumption at either extreme. Ambient salinities at stone crab
study sites have been reported as 16.3-32 ppt near Cedar Key, Florida, and
29-38 ppt in Biscayne Bay. Studies found a significant negative
correlation between the number of molting females and salinity over the
range of 33-37.5 ppt.*49*
Dissolved Oxygen. Adult stone crabs appear to be tolerant of reduced
dissolved oxygen, although the prolonged effects on viability and
reproduction are unknown. Researchers believe that crabs may be able to
survive for 17 to 21 hr in the complete absence of oxygen, and would
recover when replaced in oxygenated water. The researchers reported a
positive correlation between the quantity of oxygen available and the
extent of its use. In vitro studies indicated relatively constant
metablolic rates over the range of oxygen concentration from 0.8 to 5.6 ml
oxygen/liter of water.*49*
COMMENTS ON RESTING JUVENILE ENVIRONMENTAL ASSOC_ -
In North Carolina the smallest juvenile stone crabs were found in deep
channels where they lived beneath shell fragments. At a size of about 13
mm CW, small crabs move into shallower water and are found wherever
crevices are abundant: about rocks, jetties, pilings, and in oyster shell
rubble. At Cedar Key, Florida, juveniles less than 1.3 cm are found in
deep channels and in seagrass beds. At a larger size, 3.0 to 5.0 cm, small
crabs are found on oyster bars during the summer in the Cedar Key area.
Researchers reported oyster bars to be a least preferred habitat of stone
crabs, although researchers did find juvenile and adult crabs there.
Environment Associations - 2 (DRAFT) - Environment Associations
Species crab, stone
Species Id M070007
Date 26 AUG 96
In the Florida Keys and at Cedar Key, sponges, gorgonians, submerged rock,
and Sargassum mats are commonly used as refuges by juvenile stone crabs.
Offshore from Alligator Harbor, Florida, juveniles were commonly found in
colonies of the bryozoan Schizoporella pungens. Juvenile stone crabs are
believed to be attracted to seagrass beds both by their abundant refugia
and by Thalassia-blade epiflora and epifauna.*49*
COMMENTS ON RESTING LARVAE ENVIRONMENTAL ASSOC_ -
Larval stone crabs are not tolerant of wide temperature ranges,
particularly with reduced salinities. Researchers suggested the zoea may
not survive in 23 degrees-25 degrees C when salinities are 27 ppt or lower.
Studies found development at 20 degrees C only to the megalops stage across
the salinity range 20-40 ppt. Survival of megalopae at 20 degrees C was
less at 20-25 ppt than at 30-40 ppt, and also less than at 25 degrees and
30 degrees C. Survival to the first crab stage at both 25 degrees and 30
degrees was lower in 20 ppt than in higher salinities. No larvae survived
in a salinity of 10 ppt. Researchers suggested an optimal combination of
temperature and salinity at about 30 degrees C and 30-35 ppt.*49*
Environment Associations - 3 (DRAFT) - Life History
Species crab, stone
Species Id M070007
Date 26 AUG 96
LIFE HISTORY
PHYSICAL DESCRIPTION:
Carapace transversely oval, approximately two-thirds as long as wide,
convex, nearly smooth to unaided eye, minutely granulate and punctate.
Anterolateral border divided into four lobes: first two wide, third wide
but dentiform, fourth much narrower and dentiform. Front with a median
notch and a broad trilobulate lobe on each side. Orbital border thick,
fissures indistinct.
Chelipeds large and heavy, unequal in size, nearly smooth; inside surface of
hands with a patch of fine oblique parallel striae serving as a stridulating
organ and adapted for playing against thick edge of second and third
anterolateral teeth and outer suborbital tooth; dactyl of major chela with a
large basal tooth, and immovable finger with a large subbasal tooth; fingers
of minor chela with numerous small teeth. Walking legs stout and distally
hairy.
Color in life: Northern and western gulf form - small juveniles greenish or
bluish gray to gray or dark tan, with small dark spots on dorsal carapace
and chelae; adults are deep chocolate brown dorsally, with cream-colored to
purplish underneath carapace and chelae. Legs are dark brown and not banded
or occasionally faintly banded with yellow or cream color. Florida
peninsular gulf coast form - adults are light gray or tan dorsally on
carapace and chelae, with dark brown or grayish spots, and cream color to
white undersides. Legs are dark brown with distinct yellow to white bands
at the junctions of the segments. Juveniles are deep maroon to nearly
black, with white tips on the chelae and one to four small white spots on
dorsal carapace.
Menippe nodifrons is similar to M. mercenaria but is smaller, more purplish,
and posseses tubercles or small bumps on the anterior margin of its
carapace.*49*
REPRODUCTION:
Copulation takes place within burrows or crevices, making it difficult to
observe individual copulation or the timing of the stone crab mating season.
Researchers witnessed matings and males guarding burrows containing females
during August in North Carolina. Mating is reported to occur from November
to March at Cedar Key, Florida.
A male first courts a female for up to 12 hr and then, using his walking
legs, flips the female ventral side up beneath him. During mating, males
cradle upside-down females within their walking legs. The female telson
curves over the rear portion of the male carapace. Chelae of male crabs are
held in a defensive posture during mating, yet loss of a chela does not
seem to interfere with other aspects of the mating ritual. Copulating
females seen were freshly molted, with soft shells. Researchers described
the male's handling of the soft-shell female as being done "with care" to
avoid injury to the female. Matings lasted from 6 to 8 hr.
Life History - 1 (DRAFT) - Life History
Species crab, stone
Species Id M070007
Date 26 AUG 96
During copulation masses of sperm are transferred from male to female within
spermatophores, which are stored by the female crab within a chitin-lined
seminal receptacle. Sperm are retained in the receptacle until spawning
occurs, when only a portion of the sperm is used for fertilization of a
single batch of eggs. Researchers reported that fertilization occured
within the lumen of the ovary, although many more sperm cells attach to the
eggs within the oviducts.
A single female may produce from four to six egg masses "sponges" during a
single mating season. Researchers reported an average of 4.5 spawnings per
molt. Each egg sponge may contain between 500,000 and 1,000,000 eggs, or
from 160,000 to 350,000. The number of eggs spawned is positively
correlated with size of the female. After hatching one batch, a female may
deposit a new egg mass within a week. Spawnings may occur up to six
successive times without an intervening mating. Researchers reported that a
female spawned four times without mating or molting during a single summer,
they also reported transmolt retention of sperm by females.
The following is a description of the upright spawning position of the
female stone crab. A basket is formed of the female's extended abdomen and
the exopods of her abdominal appendages. Fertilized eggs are released into
this basket and become attached by a sticky secretion to hairs on the
exopods. After hatching occurs and larvae are released, the female scrapes
the egg shells and their stalks off these exopod hairs. Hatching is
reported to occur within 9 days to 2 weeks after spawning.
Researchers reported spawning to occur from May to July and perhaps August
in North Carolina. Further south spawning can occur year-round in Biscayne
Bay and Florida Bay. In south Florida spawning frequency is very low from
November through March. Temperature and photoperiod are primary regulators
of spawning frequency. Researchers reported accelerated ovarian development
at 29 degrees C, or during the warmest month in Biscayne Bay, with spawning
peaking during August and September. In autumn, as temperatures fall and
day length decreases, egg development reportedly slows and spawning
frequency decreases. In females, molting increases in frequency in autumn
and winter when spawning frequency decreases.*49*
BEHAVIOR:
Larval stage. Development of the planktonic larvae to first crab stage
usually requires 27 to 30 days in the laboratory, but may be altered
considerably by diet, temperature, and salinity. Larvae normally pass
through five stages. They may also enter either a prezoeal stage just after
hatching or a sixth zoeal stage. Researchers stated that neither the
observed prezoea nor the sixth zoeal stage ever molted to more advanced
stages. The prezoeal stage was believed to be caused by the stress of an
artificial environment on the developing embryos.
Larval behavior of M. mercenaria is unknown except for their positive
phototaxis and shadow response. When light levels are suddenly decreased,
Menippe larvae stop swimming and sink passively. This may be an
antipredator tactic especially against Mnemiopsis leidyi, the comb jelly,
which is an abundant predator that zoea could avoid by use of the shadow
Life History - 2 (DRAFT) - Life History
Species crab, stone
Species Id M070007
Date 26 AUG 96
response.*49*
Juvenile stage. Researchers defined juveniles to be crabs of less than 3.0
cm in carapace width (CW). During the juvenile phase M. mercenaria's
coloration patterns change from dark purple with three white dots in a
triangular pattern on the dorsal surface (juveniles less than 1.0 cm CW) to,
depending on habitat, a mottled gray to green background (juveniles greater
than 1.0 cm). Juvenile stone crabs in tanks were observed to change their
coloration patterns, after a few days, to blend with their surroundings. In
North Carolina researchers found the smallest juvenile stone crabs in deep
channels where they lived beneath shell fragments. At a size of about 13 mm
CW, small crabs move into shallower water and are found whereever crevices
are abundant: about rocks, jetties, pilings, and in oyster shell
rubble.
Juvenile stone crabs, from sites along the Texas coast, are reported to
feign death upon capture. Researchers reported that juvenile stone crabs
captured food with their walking legs and returned to their refuge to eat.
They also stridulate or produce a raspy sound by rubbing a patch of fine,
oblique, parallel striae, located on the inside surface of each cheliped,
against the thick edge of the second and third anterolateral teeth and outer
suborbital tooth. The function of stridulation in both juveniles and adults
is unknown.*49*
Adult stage. Egg-bearing females are always found on grass flats or in
channels, never on oyster bars. Few adult stone crabs were found on shallow
flats during the spring and early summer months, a peak period of spawning.
Another spawning peak occurs in late summer and early fall. Researchers
reported that adults move onto shallow grassflats in autumn. Heterosexual
pairs of crabs occupy burrows in shallow flats during fall. Pairings last
from the time of courting and mating to the time when the exoskeleton of the
newly molted female hardens. At this point the female can defend herself,
and both sexes vacate the burrow.
Adults possess a complex behavioral repertoire. They defend burrows, move
offshore and onshore as previously discussed, court before mating,
stridulate, and employ diverse modes for feeding on several types of
gastropods and bivalves. The behavioral complexity of the Menippe is
demonstrated by the manner in which it opens gastropod shells. The
attacking stone crab first manipulates the prey shell with its two large
claws and its walking legs. The minor claw or pincer may be inserted into
the snail's aperture with a probing motion that may have a chemosensory
function. The crab then positions the shell between the teeth of its
crusher and attempts to crush the spire, the siphonal canal, or the
columellar region. If crushing these areas fails because the snail is large
relative to the crab, the crab may reposition the snail so that the thumb
of the crusher can be inserted into the aperture of the shell. This places
the lip of the shell between the teeth of the crab's claw. The crab then
bends the lip outward, an action which, in juvenile snails, causes the lip
to break. This action, when repeated, "peels" the shell so that either the
fleshy snail parts are exposed or the size of the snail is reduced and may
be grasped for further attempts at crushing.*49*
Life History - 3 (DRAFT) - Life History
Species crab, stone
Species Id M070007
Date 26 AUG 96
Migrations involving one sex and/or a single size class have been reported
to occur seasonally. Females appear to be year-round residents of
grassflats, but do move from shallow to deep flats as temperatures increase
in the spring. Male crabs normally live further offshore than do females,
but move into shallower grassflat areas to mate with recently molted females
at the end of the spawning season.
Researchers described movements of nearshore M. mercenaria along the
southwest coast of Florida. Average movement of tagged individuals showed
that male movement was directed shoreward (easterly) or longshore
(northerly) during fall and winter. This pattern reversed in spring and
males moved offshore (westerly). Females moved inshore during fall and
winter, and offshore during March. After 1 month of offshore movements
females again headed shoreward. The 1-month offshore movement of females
would perhaps bring them to deeper grassflats.*49*
LIMITING FACTORS:
Predators. Larval stone crabs are undoubtedly subject to a wide range of
plankton-feeding predators as are other zooplanktonic animals. These
predators may include other planktonic animals or small fishes.
Juvenile stone crabs are preyed upon by grouper and black sea bass. They
are presumably also preyed upon by many other species of large fish.
Adult stone crabs possessing both claws can probably defend themselves
against a wide range of predators, but are eaten by a few species.
According to reports by fishermen, crabs in traps are often eaten by
octopods, sea turtles, and horse conchs. In holding tanks and in traps
stone crabs also practice cannibalism.*49*
Disease. Researchers reported a shell disease caused by several species of
chitinoclastic bacteria in several crustaceans, including stone crabs taken
from Florida waters. Menippe mercenaria from Florida's west coast
apparently are attacked by this disease more often than are crabs from the
east coast. The disease produces dark spotted areas on the exoskeleton of
its crustacean hosts. It apparently does not kill the crabs, but does
reduce the market appeal of claws.*49*
POPULATION ATTRIBUTES:
Growth. Growth for M. mercenaria, like other crustaceans, can be
characterized by the frequency of molting or intermolt interval, and by the
incremental increase in size per molt. Published descriptive data suggest
patterns for these parameters which, for the most part, await statistical
analyses. Cheliped growth and regeneration, as the basis for management of
this fishery, was the primary focus for much of the work related to growth.
Various morphometric relationships and apparently growth per se are
equivalent among males and females as juveniles, but then the sexes diverge
with sexual maturity. Researchers found an approximate intermolt interval
of 40 days for juveniles, but also noted a trend for the intermolt period to
increase with the increasing size of juvenile crabs. Researchers also found
Life History - 4 (DRAFT) - Life History
Species crab, stone
Species Id M070007
Date 26 AUG 96
Life History - 5 (DRAFT) - Life History
Species crab, stone
Species Id M070007
Date 26 AUG 96
an incremental increase in CW per molt of about 15% of the pre-exuvial
dimension, with generally smaller increments exhibited by crabs with widths
above 10 mm. Salinity and temperature were not contolled in this study, and
ranged from 23.32 to 35.68 ppt and from 15.5 degrees to 30 degrees C,
respectively, so it is not known if systematic changes in conditions
contributed to these perceived trends toward slower growth.
The transition from juvenile to adult form apparently occurs at a CW of
about 35 mm. As juveniles approach this size, their carapace shape
tranforms to the adult shape, and carapace-width versus claw-size
relationships begin to diverge between the sexes.
The reported patterns of growth among intact adults show differences between
the sexes and a trend toward slower growth in larger individuals. In
general, males are heavier and gain weight faster than females of the same
CW. This dimorphism results in part from males' having greater chelae
growth increments than females and, consequently, increasingly larger claws
for any given CW. Chelipeds account for approximately 51% of the live
weight in adult stone crabs. Furthermore, researchers suggested that summer
spawning inhibits molting by females (females molt primarily in winter).
This, too, would contribute to an overall size difference between males and
females, assuming the intermolt period of males is not similarly affected.
Autotomy or loss of a cheliped, either naturally or induced by the fishery
practice, alters both the incremental increase in CW and the intermolt
interval. Researchers reported average increments of 7.7 mm CW per molt and
6.5 mm CW for singly and doubly autotomized crabs, respectively, almost 2
and 3 mm less than for intact controls. Researchers further observed that
the intermolt interval may be shortened by autotomy just after ecdysis or
lengthened by autotomy later in the molt cycle. Claw regeneration was
nearly complete after two molts.*49*
The Fishery. Menippe mercenaria in Florida supports a unique sport and
commercial fishery in which, by law, only the claws are harvested and the
live crabs are returned to the water. The value of Florida landings places
stone crabs among the top 10 commercial marine species in the State.
Estimates of the recreational catch are not known and are considered
negligible, although almost four out of five stone crab permitholders fall
into the recreational category. The legal fishing season runs from 5
October to 15 May. During that period of 1980-81, the commercial catch of
stone crab claws has a reported dockside value of $4,873,884.
The closed summer season and minimum claw size of 7.0 cm propodus length
(2.75 inches) are intended to protect spawning females and ensure at least
one reproductive season before entry into the fishery. The requirement to
return live crabs to their habitat immediately after declawing is intended
to promote survival for regeneration of harvestable claws and added
reproduction. From tagging studies, researchers estimated 20%-25% of
legal-sized crabs were undergoing claw regeneration. Researchers further
noted claw regeneration to a harvestable size within 1 year. Experiments
showed mortality rates to be 28% and 46.5% for singly and doubly autotmized
crabs, respectively. Despite such significant mortality, allowing crabs the
opportunity to survive, regenerate, and reproduce seems preferable to the
Life History - 6 (DRAFT) - Life History
Species crab, stone
Species Id M070007
Date 26 AUG 96
alternative of harvesting entire crabs for use of just the claws.*49*
LIFE HISTORY CODES -
Average Number of Offspring/Reproductive Effort: Grea
REFERENCES FOR LIFE HISTORY- 49
Life History - 7 (DRAFT) - Management Practices
Species crab, stone
Species Id M070007
Date 26 AUG 96
MANAGEMENT PRACTICES
RESULT MANAGEMENT PRACTICE
Existing Regulating harvest - setting seasons
Existing Regulating harvest - setting size limits
Existing Other management practices [specified in comments]
REFERENCES FOR EXISTING MANAGEMENT PRACTICES - 49
COMMENTS ON MANAGEMENT PRACTICES -
Menippe mercenaria in Florida supports a unique sport and commercial fishery
in which, by law, only the claws are harvested and the live crabs are
returned to the water. The legal fishing season runs from 5 October to 15
May. During that period in 1980-81, the commercial catch of stone crab
claws has reported dockside value of $4,873,884.
The closed summer season and minimum claw size of 7.0 cm propodus length
(2.75 inches) are intended to protect spawning females and ensure at least
one reproductive season before entry into the fishery. The requirement to
return live crabs to their habitat immediately after declawing is intended
to promote survival for regeneration of harvestable claws and added
reproduction. From tagging studies, an estimated 20%-25% of legal-sized
crabs were undergoing claw regeneration. According to studies, claw
regeneration to a harvestable size was within a period of 1 year.
Experiments showed mortality rates of 28% and 46.5% for singly and doubly
autotomized crabs, repectively. Despite such significant mortality,
allowing crabs the opportunity to survive, regenerate, and reproduce seems
preferable to the alternative of harvesting entire crabs for use of just the
claws.*49*
Management Practices - 1 (DRAFT) - References
Species crab, stone
Species Id M070007
Date 26 AUG 96
References
49* Lindberg, W., M. Marshall. 1984. Species Profiles: Life
Histories and Environmental Requirements of Coastal Fishes and
Invertebrates (South Florida) --Stone Crab. U.S. Fish and
Wildlife Service Biol. Rep. 82(11.21) pp 17.
References - 1