(DRAFT) - Taxonomy
Species lobster, spiny
Species Id M070009
Date 26 AUG 96

TAXONOMY

NAME - lobster, spiny

OTHER COMMON NAMES - crawfish, crayfish, Florida spiny lobster, western Atlantic spiny lobster, Caribbean spiny lobster, rock lobster and "bug"

ELEMENT CODE -

CATEGORY - Aquatic Crustaceans

PHYLUM AND SUBPHYLUM - ,

CLASS AND SUBCLASS - Crustacea,

ORDER AND SUBORDER - Decapoda,

FAMILY AND SUBFAMILY - Palinuridae,

GENUS AND SUBGENUS - Panulirus,

SPECIES AND SSP - argus,

SCIENTIFIC NAME - Panulirus argus

AUTHORITY - Latreille

TAXONOMY REFERENCES - 43

COMMENTS ON TAXONOMY -
Preferred common name..Spiny lobster, crawfish.

Other common names...Crayfish, Florida spiny lobster, Western Atlantic spiny
lobster, Caribbean spiny lobster, rock lobster, "bug".*43*

Taxonomy - 1 (DRAFT) - Status
Species lobster, spiny
Species Id M070009
Date 26 AUG 96

STATUS

Coded Status
Sport Fish
Biological Indicator
Commercial

REFERENCES FOR STATUS - 43

COMMENTS ON STATUS -
Panulirus argus supports major commercial fisheries in south Florida, the
Bahamas, Cuba, Brazil, and throughout the Caribbean. Spiny lobsters are
mid- to high-level predators and probably are important in structuring
marine benthic communities. Throughout their lives, lobsters live among
diverse habitats and exhibit behavioral and physiological characteristics
that make them excellent test organisms for basic research.*43*

Status - 1 (DRAFT) - Distribution
Species lobster, spiny
Species Id M070009
Date 26 AUG 96

DISTRIBUTION

Distribution - 1 HABITAT ASSOCIATIONS

NATIONAL WETLAND INVENTORY CODES

NWI NWICLS NWIMOD NWISPEC

Estuarine RB. G
Estuarine FL2 G
Estuarine RF1 G
Estuarine RS1 G
Marine RB. G
Marine FL2 G
Marine RF1 G
Marine OW0 G
Estuarine AB. G 1
Estuarine RS. G 1
Estuarine AB1 G
Estuarine UB. G
Marine OW0 G
Estuarine RS. G

REFERENCES FOR NWI - 43

COMMENTS ON HABITAT ASSOCIATIONS -
Little is known about factors that stimulate postlarval settlement and
specific habitat requirements of early juveniles. Researchers caught
postlarvae and young juveniles up to 25 mm long among algal-fouled mangrove
roots and algal clumps collected from shallow seagrass beds. Researchers
observed postlarvae and juveniles up to 20 mm long in shallow (2-3 m)
macroalgal assemblages dominated by several species of the red alga
Laurencia. Somewhat later stages inhabited small holes and crevices within
a shallow, algal-fouled rubble zone dominated by various red algae,
primarily Laurencia. Researchers reported substantial catches of lobsters
11 to 30 mm long in Biscayne Bay by bait shrimp trawlers. Trawling took
place over sand/mud bottoms with abundant seagrasses, calcareous green
algae, and Laurencia.

Early benthic larvae and juveniles apparently concentrate in macroalgae beds
along rocky shorelines and may be interspersed among large expanses of
seagrass that typify known nursery areas like Florida Bay.

Early benthic lobsters tend to live a solitary existence. Because they have
easy access to their food supply, foraging time for young juveniles and
exposure to predators are minimal. Young juveniles are highly aggressive,
using the antennae to lash or pry conspecifics, suggesting that dispersed
spacing patterns may be maintained by agonistic behavior.*43*

Late Juvenile and Adult Life Stages. Most lobsters longer than 20 mm
aggregate in various sheltering structures in protected bays, including
estuaries with high salinity. Shelters include large sponges, coral heads,
mangrove roots, grass-bed undercuts, solution holes, rocky outcroppings or
ledges, and even clumps of sea urchins. Most shelters supply partial
camouflage, physically deter predators, and provide refuge from physical
stress. Adult coloration replaces the cryptic pattern, and late juveniles
begin to exhibit active antipredator defense using the antennae as foils.

The ontogenetic transition from "solitary-asocial" to "aggregative-social"
is apparently not rigidly fixed, and probably depends in part on the
distribution and physical characteristics of lobster shelter. Juveniles
tend to be nomadic, usually taking shelter after foraging at night. Where
juvenile density is high, transient movements are especially apparent in
Habitat Associations - 1 areas of intermittent shelter, e.g., the shallow waters of the Florida Keys.

Lobsters approaching maturity (70-80 mm) emigrate offshore. These
emigrations are usually gradual and nomadic, but short-term mass movements
do occur. These movements widely disperse the lobsters along the reefs
that parallel the Florida Keys. Sex ratios inshore indicate that more
females than males emigrate offshore.

Offshore lobster populations are composed predominantly of adults residing
individually or communally in crevices of rock or coral. After foraging at
night (up to several hundred meters) most adults return to the same or
nearby dens. Homing apparently involves orientation of the lobster to
hydrodynamic (current and wave surge), chemical, topographic, and
gravitational (slope) cues. Adult lobsters are highly selective of
dens, residing most frequently in crevices that allow full withdrawal of
the body, deny access by large predators, and contain other lobsters.*43*

Habitat Associations - 2 (DRAFT) - Food Habits
Species lobster, spiny
Species Id M070009
Date 26 AUG 96

FOOD HABITS

TROPHIC LEVEL -
CARNIVORE

REFERENCES FOR TROPHIC LEVEL - 43

LIFESTAGE FOOD FOOD PART
Larva Osteichthyes Larva stage
Larva Hydrozoans Not Specified
Larva Crustaceans Not Specified
Larva See Comments; Food
Juvenile Molluscs Not Specified
Juvenile Crustaceans Not Specified
Juvenile Starfish Not Specified
Juvenile See Comments; Food
Adult Molluscs Not Specified
Adult Crustaceans Not Specified
Adult Starfish Not Specified
Adult See Comments; Food

REFERENCES FOR GENERAL FOOD - 43

REFERENCES FOR ADULT FOOD - 43

REFERENCES FOR JUVENILE FOOD - 43

REFERENCES FOR LARVAE FOOD - 43

COMMENTS ON FOOD -
Lobsters are nocturnal foragers throughout the benthic phase, locating food
with chemoreceptive setae lining the antennules and dactyls of the walking
legs. They prey upon a wide variety of slow-moving and sedentary animals,
including gastropod and bivalve mollusks, crustaceans, and echinoderms.
Powerful mandibles crush or chip away at molluscan shells and other types of
protective armor. Variation in the diets among recently settled juveniles
in concentrations of algae, older juveniles in inshore bays, and adults on
coral reefs probably reflect differing prey availability among habitats.
Spiny lobsters often are the dominant carnivores (as indicated by total
biomass) in their habitat and probably have important ecological effects on
marine benthic communities.*43*

COMMENTS ON LARVAE FOOD -
The diet of spiny lobster phyllosomes has not been sufficiently described.
Phyllosomes in culture eat chaetognaths, euphausiids, fish larvae, medusae,
and ctenophores. There are no indications that pueruli feed at all.*43*

Food Habits - 1 (DRAFT) - Environment Associations
Species lobster, spiny
Species Id M070009
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
L Turbidity: Clear water
J Bottom Type [Aquatic]: Rooted aquatic vegetation
J Density of Aquatic Vegetation: High
J Relation to Substrate: Specified in Comments
L Trophogenic Zones: Well-lighted
A Relation to Substrate: Specified in Comments
G Water Temperature: Greater than 27 degrees C
G Water Temperature: Between 21-27 degrees C
G Water Temperature: Between 15-21 degrees C
G Water Temperature: Specified in Comments
G
G
LIM
LIM
L
L Aquatic Habitat Zonation: Shallows with emergent vegetation [littoral zone]
G Coastal Features: Reefs
G Currents: specified in comments
L Coastal Features: Rocky beaches
J Coastal Features: Rocky beaches
L Estuarine habitat zone: bay
A Estuarine habitat zone: offshore
A Turbidity: Clear water

REFERENCES FOR ENVIRONMENTAL ASSOC_ - 43

REFERENCES FOR LIMITING ENVIRONMENTAL ASSOC_ - 43

REFERENCES FOR RESTING ADULT ENVIRONMENTAL ASSOC_ - 43

REFERENCES FOR RESTING JUVENILE ENVIRONMENTAL ASSOC_ - 43

REFERENCES FOR RESTING LARVAE ENVIRONMENTAL ASSOC_ - 43

COMMENTS ON ENVIRONMENTAL ASSOCIATIONS -
Currents. Throughout benthic life, lobsters are influenced by
hydrodynamic forces and stimuli (currents, wave surge, turbulance).
Puerulus settlement is reduced in areas of strong currents, e.g., channels
between the Florida Keys. The postsettlement period may be disrupted by
Environment Associations - 1 (DRAFT) - Environment Associations
Species lobster, spiny
Species Id M070009
Date 26 AUG 96

disturbances that alter shelter, interfere with foraging, or cause bodily
abrasion. Subadults and adults respond to sharply increased currents and
turbulence caused by the first autumnal storms by mass migration.*43*

Temperature. Spiny lobsters generally inhabit waters with annual minimum
monthly temperatures that exceed 20 degrees C. Along the northern edge of
their distribution in Florida, mean monthly water temperatures rarely fall
below 16 degrees C. This is just above reported minimum survival
temperatures for both larval and benthic life stages. Phyllosomes of the
slipper lobster, Scyllarus americanus, which has a geographic range similar
to the spiny lobster, show retarded development at water temperatures below
16 degrees C. Postlarval and young juvenile spiny lobster grow slower and
demonstrate higher mortality at temperatures sustained below 16 degrees C.
Postlarval tolerance of short-term, sharp temperature declines to 13 degrees
C protects them against severe but short-lived cold fronts that sometimes
frequent south Florida.

At water temperatures near 13 degrees C, spiny lobsters 65-85 mm CL
demonstrate reduced locomoter activity and an inabilty to capture and
manipulate prey. Direct mortality may occur, especially for lobsters
undergoing ecdysis, during rapid water temperature declines to as low as 10
degrees C. Poor survival at low temperatures, especially if they are
sustained for several days, probably limits both the latitudinal and depth
distributions of spiny lobsters as well as preventing migration across deep
ocean basins like the Florida Straits.

The annual water temperature range in lobster habitats in south Florida is
about 18 degrees to 31 degrees C. Sharp temperature fluctuations within
this range may alter the normal rate of growth of lobsters and their time
of settlement. Growth is rapid but survival is poor at temperatures
exceeding 32 degrees C. Newly settled postlarvae are particlarly vulnerable
during temperature extremes and disturbances by hurricanes and winter
storms.
Fluctuations in juvenile abundance probably are caused by interactions
between the rate of settlement and seasonal environmental conditions.*43*

COMMENTS ON RESTING ADULT ENVIRONMENTAL ASSOC_ -
Adults inhabit coral reef crevices or overhangs, rocky outcroppings,
ledges, and other discontinuities in hard substrate. Residential patterns
of habitation are apparent in large, permanent dwellings near extensive
feeding grounds. Soft-substrate shelters, like grass-bed ledges, are
occupied primarily during nomadic movements. Muddy, turbidity-prone
substrates are usually avoided.*43*

COMMENTS ON RESTING JUVENILE ENVIRONMENTAL ASSOC_ -
Juveniles larger than 20 mm CL take refuge in both biotic (sponges, small
coral heads, sea urchins) and abiotic (ledges, solution holes) structures.
The importance of shelter availability on population distribution is
magnified because, unlike clawed lobsters, spiny lobsters can modify but
not construct dens.*43*

COMMENTS ON RESTING LARVAE ENVIRONMENTAL ASSOC_ -
Salinity. Postlarvae do not usually tolerate salinities below 19 parts
Environment Associations - 2 (DRAFT) - Environment Associations
Species lobster, spiny
Species Id M070009
Date 26 AUG 96

per thousand (ppt). Along the northern Gulf of Mexico, adverse synergistic
effects of reduced temperature and variable salinities probably prevent
recruitment into nearshore habitats.*43*

Environment Associations - 3 (DRAFT) - Life History
Species lobster, spiny
Species Id M070009
Date 26 AUG 96

LIFE HISTORY

PHYSICAL DESCRIPTION:

General: The subcylindrical carapace is studded with forward-projecting
spines, and prominent rostral horns extend over stalked eyes. Long,
whip-like antennae are tapered anteriorly and covered with small spines.
The slender, elongate walking legs (pereopods) bear setose dactyls. The
tail is smooth except where notched along the lateral edges, and the
transverse groove on each tail segment is interrupted at the midline. The
tail fan is composed of a central telson bordered by a pair of biramous
uropods.

Color: In young juveniles (7 to 20 mm carapace lengths unless otherwise
stated), the antennae and pereopods are banded with distinct white stripes;
a broad white stripe extends along the dorsal midline of the carapace and
abdomen. The general body colors are shades of brown, black, and purple.
Adult color varies from light gray or tan with green and brown shades to
deeper brown with red and black shades. The second and sixth tail segments
have large white or yellowish ocelli; small ocelli are dorsolateral on other
tail segments. The legs are striped longitudinally with dull blue, and the
pleopods are bright orange and black.

Sexual dimorphism: Females are distinguished by the small chela on the
dactyls of the fifth pereopods; the adult male is characterized by an
elongate second pair of legs bearing extended, curved dactyls. The
endopodite of female pleopods is well developed, hooklike, and heavily
setose. In males, the raised genital openings lie at the base of the fifth
pair of legs; in females they lie at the base of the third pair of legs.
The female sternum is striated and narrower at its posterior margin than in
the male.

Related species: The sympatric P. laevicauda has no dorsal grooves on the
tail segments and bears small white spots along the lateral margin of the
tail; P. guttatus has a single, uninterrupted transverse groove on the
second through the fifth tail segments and has many white spots over the
body.*43*

REPRODUCTION:

Most spiny lobster in Florida waters reproduce during late spring and early
summer. Yearly variations in peak spawning time depend largely on water
temperature. Researchers reported optimal spawning at 24 degrees C, whereas
in other studies spawning was observed to begin at 24 degrees C in deep reed
areas (30 m). In Florida, there is no direct evidence that lobsters spawn
more than once a year, but some repeat spawning by some individuals is
suspected in Bermuda waters.

The spiny lobster spawns in offshore waters along the deeper reef fringes.
Although adult males and females sometimes inhabit bays, lagoons, estuaries,
and shallow banks, none are known to spawn there. Requirements of offshore
spawning are high shelter quality, suitable water conditions (stable
temperature and salinity, low surge and turbidity), and adequate larval
Life History - 1 (DRAFT) - Life History
Species lobster, spiny
Species Id M070009
Date 26 AUG 96

transport by oceanic currents.

Mating follows a brief courtship involving signals by both male and female.
During copulation, the male holds the female sternum to sternum against him
and extrudes a spermatophoric mass. The gray tarry spermatophore adheres to
the female sternum until spawning. The sperm may remain viable for as long
as one month.

During the spawning, the female abdomen is flexed in cuplike fashion beneath
the cephalothorax, and the telson uropods are spread. Eggs (spherical, 0.5
mm diamter) are liberated externally through the gonopores located at the
base of the third pair of walking legs. Fertilization begins as a female
scratches at the spermatophore packet using the chelate dactyls of the fifth
walking legs. The bright orange, yolk-filled eggs adhere to hooklike
pleopodal setae on the underside of the abdomen. Fecundity varies directly
with size: females 71 to 75 mm long carry 230,000 eggs; females longer than
100 mm may carry over 700,000 eggs. Embryonic development lasts about 3
weeks. The eggs turn brown a few days before hatching. The phyllosomes
emerge from the egg membrane and disperse into the water column assisted by
abdominal movements of the female.

The relative (percentage) contribution of each size class in the population
to the total number of eggs layed can be estimated using the Index of
Reproductive Potential, which states:

IRP = (A x B x C)/D

where A = total females within a given size class/total females in the
population
B = % of females bearing eggs in that size class
C = fecundity of females in that size class
D = a constant (total eggs laid/100%) derived to set the index of a
particular size class at the percentage contribution to the
total egg production.

Applying the IRP to the lobster population of the upper Florida Keys,
researchers estimated that the 76-85 mm Cl size class contributed 48% of
total egg production. Females longer than 85 mm made up only 20% of all
females, but contributed about 41% of eggs. Smaller size classes (< 76 mm
CL) constituted 25% of all females, but contributed only 11% of the eggs.
Compared to the index values for the unfished population at Dry Tortugas,
researchers estimated that egg production in the Florida Keys was only 12%
of that to be expected from an unfished population of similar size.

Intense fishing may have caused a decline in the minimum size of spawning
females in Florida waters. The smallest egg-bearing females reported by
researchers in 1922 were 76 mm, but in recent surveys egg-bearing females
were as small as 71 mm and 65 mm. In contrast, the smallest egg bearer
observed from an unfished population at Dry Tortugas was 78 mm. Suggested
causes for this apparent decline in size are genetic selection, modified
sexual behavior when large females are rare, and reduced growth caused by
high injury rates. The minimum legal size may not adequately protect
spawning stock in Florida.*43*
Life History - 2 (DRAFT) - Life History
Species lobster, spiny
Species Id M070009
Date 26 AUG 96

BEHAVIOR:

Larvae Lifestage. Eggs hatch as transparent, phyllosome (leaf-bodied)
larvae. They are morphologically well equipped for planktonic life, bearing
long, highly setose appendages extending from a dorsoventrally flattened,
bilobed cephalothorax. Phyllosomes swim in a horizontal position by means
of the exopodal action of the biramous legs. They undergo a diel pattern of
vertical distribution, ascending to surface waters at night and descending
during the day. Distribution is otherwise regulated by ocean currents and
other factors that influence water circulation patterns.

Phyllosomes develop through about 11 stages, increasing in size from 2 mm
(total length) at hatching to nearly 34 mm before metamorphosis. Duration
of the phyllosome stage is about 6 to 12 months.

The uncertainty of the duration of the phyllosome stage renders the question
of larval origins problematic. Major factors causing uncertainty are
variation in growth rates, delays in metamorphosis, the widespread abundance
of larvae, and the inherent complexities of oceanic circulation throughout
the western Atlantic region. The larval source for Florida is unknown, but
two different origins are proposed: (1) larvae of Caribbean spawning
stocks are transported downcurrent to Florida, and (2) larvae of local
stocks are retained by idiosyncratic current patterns off the coast of
Florida. Neither proposal is conclusive, and new research approaches are
under study, particularly biochemcial genetics.*43*

Postlarvae and Early Juvenile Life Stages. The spiny lobster larva
metamorphoses into a puerulus, a brief (several weeks), nonfeeding, oceanic
phase. The puerulus possesses a number of distinctive features including
adaptations for rapid, efficient swimming (e.g., a smooth, lightweight
transparent body lacking calcification and spines, and a dorsoventrally
flattened carapace).

After metamorphosis offshore, pueruli swim shoreward by night, antennae
directed forward, within a few centimeters of the water surface. Propulsion
is provided by specialized abdominal pleopods. Large numbers of peuruli
arrive along the southeast Floria coast and southern shores of the Florida
Keys throughout the year, principally during the new and first-quarter lunar
phases. The season of peak recruitment varies considerably from year to
year and regionally, but maximum numbers generally arrive inshore in spring;
there is a lesser peak in fall. Because Florida lobsters spawn almost
exclusively in late spring, year-round recruitment of larvae suggests that
a substantial number of pueruli originate elsewhere.

Pueruli settle rapidly when they encounter suitable inshore substrate.
They acquire reddish-brown pigmentation and within days molt into the first
juvenile stage. The distinctive color patterns of early benthic juveniles
are a combination of cryptic (different shades) and disruptive (bands or
stripes) features that make juveniles in vegetation nearly invisible.

Little is known about factors that stimulate postlarval settlement and
specific habitat requirements of early juveniles. Researchers caught
Life History - 3 (DRAFT) - Life History
Species lobster, spiny
Species Id M070009
Date 26 AUG 96

postlarvae and young juveniles up to 25 mm long among algal-fouled mangrove
roots and algal clumps collected from shallow seagrass beds. Researchers
observed postlarvae and juveniles up to 20 mm long in shallow (2-3 m)
macroalgal assemblages dominated by several species of the red alga
Laurencia. Somewhat later stages inhabited small holes and crevices within
a shallow, algal-fouled rubble zone dominated by various red algae,
primarily Laurencia. Researchers reported substantial catches of lobsters
11 to 30 mm long in Biscayne Bay by bait shrimp trawlers. Trawling took
place over sand/mud bottoms with abundant seagrasses, calcareous green
algae, and Laurencia.

Early benthic lobsters tend to live a solitary existence. Because they
have easy access to their food supply, foraging time for young juveniles and
exposure to predators are minimal. Young juveniles are highly aggressive,
using the antennae to lash or pry conspecifics, suggesting that dispersed
spacing patterns may be maintained by agonistic behavior.*43*

The ontogenetic transition from "solitary-asocial" to "aggregative-social"
is apparently not rigidly fixed, and probably depends in part on the
distribution and physical characteristics of lobster shelter. Juveniles
tend to be nomadic, usually taking shelter after foraging at night. Where
juvenile density is high, transient movements are especially apparent in
areas of intermittent shelter, e.g., the shallow waters of the Florida Keys.

Offshore lobster populations are composed predominantly of adults residing
individually or communally in crevices of rock or coral. After foraging at
night (up to several hundred meters) most adults return to the same or
nearby dens. Homing apparently involves orientation of the lobster to
hydrodynamic (current and wave surge), chemical, topographic, and
gravitational (slope) cues. Adult lobsters are highly selective of
dens, residing most frequently in crevices that allow full withdrawal of the
body, deny access by large predators, and contain other lobsters. The
preference for an occupied den is generally interpreted as a social
response, i.e., being attracted to conspecifics. Both late juveniles and
Life History - 4 (DRAFT) - Life History
Species lobster, spiny
Species Id M070009
Date 26 AUG 96

adults are gregarious.

The tendency for adult lobsters to congregate probably is a requirement for
adequate defense, mating, and shelter use. Lobsters may resist predators by
blocking large den openings or by forming a cohesive group adjacent to less
formidable shelters like sponges and sea whips. Males initiate mating by
seeking receptive females often found congregated during the day.

Concentrations of spiny lobsters in the waters of the Florida Keys tend to
shift in autumn and during the spring reproductive period. Some movements
are sex dependent and sometimes cause sharp differences in male-female
ratios from place to place. Females move to deeper reefs in the spring,
presumably to mate and shed larvae. At Dry Tortugas, females return to
shallow water after releasing their larvae. Normal sex ratios (about 1:1)
are restored by fall. Both sexes emigrate offshore in the fall as water
temperatures decline and fall storms arrive. Sometimes offshore movements
are spectacular mass migrations of lobsters forming single-file columns or
queues.*43*

Migration. The role of sharply increased hydrodynamics in triggering
migratory queuing has been experimentally demonstrated. Mass migration by
spiny lobster may redistribute migrants into stable overwintering habitat in
deeper reef areas near the Gulf Stream. Current flow provides a directional
cue both for general orientation and for locating food by chemosenses.*43*

LIMITING FACTORS:

Predators. Substantial numbers of larvae and postlarvae are probably eaten
by pelagic fishes. Pueruli are eaten by benthic (or epibenthic) fauna as
well. Octopods and portunid crabs prey on recently settled juveniles.
Experiments in aquaria indicate that small fishes (e.g., gray snappers) are
probably the most important predators on early benthic stages. Because of
their relatively large size, spiny exoskeleton, rapid tail-flip escape
response, and defense by group formation, late juveniles and adults are well
protected from small predators. Large predators, primarily groupers,
jewfish, sharks, loggerhead turtles, and octopods, prey on both juvenile and
adult lobsters. Stomachs of large jewfish often contain large lobsters.*43*

Competition. Competition among lobster species in Florida waters appears to
be inconsequential. The other local shallow-dwelling species, Panulirus
laevicauda and P. guttatus, are relatively scarce and are restricted mainly
to reef habitats.*43*

Habitat. Phyllosoma larvae require relatively stable natural conditions for
optimum survival. Researchers noted that spiny lobster larvae are
extremely delicate, physically, and inordinately fastidious,
physiologically. Larvae are particularly sensitive to silt particles, which
can, in extreme instances, lodge on their setae, weigh them down, and cause
death. Because nutritional requirements change throughout the life of the
larvae, enchanced growth and survival require a diverse, productive oceanic
plankton community,. There are positive correlations between plankton
biomass and density of late-stage phyllosomes.*43*

Life History - 5 (DRAFT) - Life History
Species lobster, spiny
Species Id M070009
Date 26 AUG 96

The annual water temperature range in lobster habitats in south Florida is
about 18-31 degrees C. Sharp temperature fluctuations within this
range may alter the normal rate of growth of lobsters and their time of
settlement. Growth is rapid but survival is poor at temperatures exceeding
32 degrees C. Newly settled postlarvae are particlarly vulnerable during
temperature extremes and disturbances by hurricanes and winter storms.
Fluctuations in juvenile abundance probably are caused by interactions
between the rate of settlement and seasonal environmental conditions.*43*

Salinity. Postlarvae do not usually tolerate salinities below 19 parts per
thousand (ppt). Along the northern Gulf of Mexico, adverse synergistic
effects of reduced temperature and variable salinities probably prevent
recruitment into nearshore habitats. Recruitment patterns were disrupted in
both 1966 and 1968 in the St. Lucie Estuary when heavy freshwater inflow
reduced salinity to below 19 ppt. Older juveniles are able to use marginal
inshore habitats because they are highly mobile and can retreat from
unsuitable physical conditions.*43*

Hydrodynamics. Throughout benthic life, lobsters are influenced by
hydrodynamic forces and stimuli (currents, wave surge, turbulance).
Puerulus settlement is reduced in areas of strong currents, e.g., channels
between the Florida Keys. The postsettlement period may be disrupted by
disturbances that alter shelter, interfere with foraging, or cause bodily
abrasion. Subadults and adults respond to sharply increased currents and
turbulence caused by the first autumnal storms by mass migration. Mass
movements are particularly striking. The lobsters form single-file lines,
or queues, and march in locally precise directions day and night for up to 1
week.*43*

POPULATION ATTRIBUTES:

Life History - 6 (DRAFT) - Life History
Species lobster, spiny
Species Id M070009
Date 26 AUG 96

Growth Characteristics. The growth of the spiny lobster is largely
correlated with the frequency of molting and increment growth while molting.
Generally, the frequency of the molts and increment growth decline with age.
Variation is caused partly by differences in methodology used to estimate
growth, but most differences are caused by changes in environmental
conditions. Local variability in food abundance, population density,
predatory attacks (inducing injuries), and water temperature greatly affects
growth rates of spiny lobsters.

The monthly growth rate of spiny lobster (starting with pueruli 6 mm CL)
reared for 7 months was 3.8 to 4.2 mm/mo, given an average size of 34 mm (6
mm CL at metamorphosis plus 7 x 4 mm or 28 mm); an average growth rate of 5
mm/mo for the first 9-10 months after settlement was estimated from length
(CL) frequency data from lobster sampled in Biscayne Bay. The pattern of
length frequency, however, is reliable only up to lengths of 25 mm, after
which interpretations of field data are seriouly biased by the lack of
distinct settling classes. Young juveniles confined in small aquaria with a
limited diversity of food grew substantially slower (< 2 mm/mo) than most
natural populations.

Growth rates were estimated during a 2-year tag-and-recapture study in
Biscayne Bay and Florida Bay, both of which are major nursery areas. In
Biscayne Bay, the mean growth rate of lobsters 40-85 mm long was 1.8 mm/mo.
The physical condition of individuals significantly affected growth:
uninjured lobsters grew 2.2 mm/mo, but those missing legs and antennae grew
only 1.3 mm/mo, a 41% reduction. In Florida Bay, mean growth rate of
lobsters of about the same size was 3.3 mm/mo. Injured lobsters grew nearly
as fast. Researchers attributed increased growth and the lack of damaging
effects from injury to optimal growing conditions and low fishing effort in
Florida Bay. In waters near Key West, tagged lobsters 49 to 83 mm long grew
an average of 3.1 mm/mo.

The postsettlement time required for juveniles to reach minimum legal size
is important to fishery management. The first 7 months of each growth
estimate after the beginning of the puerulus stage (6 mm CL) are based on a
mean growth rate of 4.0 mm/mo; thus the lobsters are 34 mm long 7 months
after settling. The remaining 17 months of each estimate are based on
growth rates of lobsters over 40 mm long in various areas. For example, the
estimated carapace length of injured Florida Bay lobsters after 2 years was
34 mm + (17 mo x 3.2 mm/mo) = 88 mm. The estimated number of months to
reach legal size (76 mm) is obtained by dividing 42 mm (76 mm - 34 mm = 42,
the growth rate after 7 months and adding 7 months. From the above data it
was calculated that the lobsters reach legal length in about 20 months (42
mm/3.2 mm/mo = 7 mo).

An interaction between sex and growth of spiny lobsters in known. Lobsters
of the two sexes show near equal growth in the nurseries of Florida Bay and
Biscayne Bay. However, adult female lobsters grow slower than males. This
growth differential has been reported for the lower Florida Keys.

Population Size Composition and Reproductive Potential. Researchers noted a
12-mm decrease (90 mm to 78 mm CL) in the modal length of Florida Keys
lobsters since 1945-49. The modal carapace length of 78 mm is about 30%
Life History - 7 (DRAFT) - Life History
Species lobster, spiny
Species Id M070009
Date 26 AUG 96

smaller than that of the unfished population at Dry Tortugas. The decline
in the size of the mature female has caused a marked reduction in
reproduction potential (egg production). Researchers estimated the Florida
Keys population spawns only 12% of the number of eggs of an unfished
population of equal number because the fishery selected and effectively
removed the larger, more fecund females. If the decrease in eggs spawned
causes a decrease in larvae and recruitment into the fishery, then spawning
stocks will have to be better protected. If locally spawned larvae are
significant contributors, suggested actions include increasing the minimum
legal size and establishing sanctuaries where large, fecund females are
protected. If larvae from Florida support lobster fisheries outside of
Florida waters and vice versa, cooperative international management
agreements may be required.

Fishery-Induced Juvenile Mortality/Growth Reduction. Laws enacted in 1976
allow fishermen in Florida to use small, illegal lobsters (locally termed
"shorts") as decoys in traps. Fishermen prefer "shorts" over conventional
baits such as cowhide or fish heads. Studies confirm that catch rates
increase with the number of "shorts" used per trap. This practice causes
substantial mortality among juvenile stocks. Major stresses are boatside
transport and starvation during confinement. Loss to the fishery may be
substantial because in the 1980's over 500,000 traps are being fished, and
fishermen typcially use three to five "shorts" per trap. Attempts are
underway to develop artificial lures as a low-cost alternative. Another
approach would be to require openings of sufficient size among the slats
(escape gaps) to allow all undersized lobsters to escape.

Injuries to juvenile lobsters (loss of antennae and legs) are commonly
caused by attacks from predators and from handling by commercial fishermen
and sport divers. In Biscayne Bay, the frequency of injuries increased as
much as 50% during the fishing season. Less frequent injuries were reported
for the middle and upper Florida Keys. Injured lobsters grow slower than
uninjured lobsters presumably because they are less efficient foragers and
because growth is redirected into limb regeneration. Researchers estimated
that injuries from commercial handling in Biscayne Bay caused an annual loss
of 31,000 lobsters. Researchers presented evidence that injuries cause high
mortality among small (less than legal size) lobsters in the Florida Keys.
The Florida State Legislature established a lobster sanctuary in Biscayne
Bay in 1979, and the Everglades National Park portion of Florida Bay was
closed to recreational lobstering in 1980; both measures were designed to
protect juveniles.

Maximum sustainable yield (MSY) for lobster landings in Monroe County is
estimated to be 5.9 million lb, on the basis of catch and fishing intensity
data obtained from 1952 to 1975. If domestic catches (0.2 million lb) were
included, the actual MSY would be nearer to 12 million lb.*43*

OTHER MISCELLANEOUS LIFE HISTORY INFORMATION:

Oceanic Circulation. Because the movement of phyllosoma larvae is
restricted to vertical migration, ocean circulation patterns are responsible
for spreading larvae into distant waters. These patterns consist of (1)
initial dispersal of larvae from spawning sites; (2) long-distance transport
Life History - 8 (DRAFT) - Life History
Species lobster, spiny
Species Id M070009
Date 26 AUG 96

or retention of larvae; and (3) transport of larvae to nursery grounds.
Mechanisms involved in larval transport to south Florida are poorly
understood because of complex interactions of major currents of the Gulf of
Mexico and Caribbean Sea, seasonal variation in current patterns off the
Florida coast, and uncertainty of the extent to which phyllosomes regulate
their horizontal distribution by vertical migration into and out of
divergent water masses. Transport models proposed for other spiny lobster
species cannot be strictly applied to spiny lobsters in Florida.*43*

LIFE HISTORY CODES -
Gestation/Incubation Period: 3-4 weeks
Average Number of Offspring/Reproductive Effort: Grea
Nest/Den Site: Ledges
Nest/Den Site: Emergent aquatic vegetation
Nest/Den Site: Under rocks/rock outcrops
Periodicity: Active at night
Dispersion: Clumped
Spawning Site: Aquatic Vegetation
Nest/Den Site: Secondary Cavity (use cavity excavated

REFERENCES FOR LIFE HISTORY- 43

Life History - 9 (DRAFT) - Management Practices
Species lobster, spiny
Species Id M070009
Date 26 AUG 96

MANAGEMENT PRACTICES

RESULT MANAGEMENT PRACTICE

Existing Regulating harvest - setting seasons
Existing Regulating harvest - setting size limits

REFERENCES FOR EXISTING MANAGEMENT PRACTICES - 43 43

COMMENTS ON MANAGEMENT PRACTICES -
Regulations in 1984 prohibited lobster fishing from 1 April throuh 25 July
and required that all lobsters must be > 76 mm CL or have tail lengths
of at least 140 mm. Egg-bearing females must be returned to the sea.*43*

Management Practices - 1 (DRAFT) - References
Species lobster, spiny
Species Id M070009
Date 26 AUG 96

References

43* Marx, J., W. Herrnkind. 1986. Species Profiles: Life Histories
and Environmental Requirements of Coastal Fishes and
Invertebrates (South Florida) -- Spiny Lobster. U.S. Fish and
Wildlife Service Biol. Rep. 82(11.61) pp 21.

References - 1