# Presentation: 920184

## A Review of the Literature and Life History Study of the Caribbean Spiny Lobster, Panulirus Argus

**Steven Saul**
- NMFS Southeast Fisheries Science Center
- Sustainable Fisheries Division

**Notes:**
Given the economic significance of the Caribbean Spiny lobster (Panulirus argus) to both commercial and artisanal fisheries, many individuals have sought to describe and document the life history, behavior, and general biology of this species. In order to fully devise management strategies for the efficient harvesting of P. argus, a review of the life history information on Caribbean spiny lobsters is necessary.  The following presentation will discuss the distribution, habitat, stock structure, morphology, feeding habits, reproductive behaviors and growth of the Caribbean spiny lobster.  

## Panulirus argus Distribution

*Figure 1*

**Notes:**
The Caribbean Spiny lobster populates the Western Atlantic Ocean, Caribbean Sea, and Gulf of Mexico ranging from Bermuda down to Brazil.  Distribution and dispersal of P. argus is determined by the comparatively long planktonic larval phase, called the puerulus, during which time the infant lobsters are carried by the currents, and other factors until they become large enough to settle to the bottom. The long duration that lobsters spend in the larval stage, severely impairs the ability of scientists to determine a stock structure for this species.  More recent work with DNA may be useful in determining some sort of stock structure for the Caribbean spiny lobster (Lipcius and Cobb, 1994), however the extensive larval phase may also limit this tool as it takes few successful migrants to homogenize the gene pool (Silberman and Walsh 1994).  Studies have also shown that the presence of local gyres or loop currents in certain locations could influence the retention of locally spawned larvae.  In addition, benthic structures such as coral reef may disturb the flow of water and lead to the settlement of larvae in a particular location (Lee, et. al. 1994). 

## Morphology

*Figure 2*

**Notes:**
The general anatomy of Panulirus argus conforms to the typical decapod body plan consisting of five cephalic and eight thoracic segments fused together to form the cephalothorax.  The carapace, a hard shield-like structure, protects this portion of the body and is often the part of the lobster used to determine organism length. The antennae function primarily to obtain sensory information by chemoreception, as do the dactyls of the walking legs and the mouthparts involved in handling food.  Lobsters have great visual ability, achieved through the use of their paired, lateral compound eyes.  In addition, highly distributed superficial hairs detect water movements (Ache and Macmillan, 1980). Gills are the main organs used by lobsters for respiration.  The rate of oxygen consumption in P. argus is dependent upon the temperature, the degree of crowding within the den, feeding and size of the lobster; oxygen consumption is not determined by the concentration of the oxygen in the water as some studies show that oxygen uptake remained the same in both hypoxic and aerated water (Phillips, Cobb and George, 1980). 

## Life Cycle

*Figure 3*

**Notes:**
After the planktonic phase (called the puerulus),  spiny lobsters enter the seagrass and macroalgae nursery habitat.  Their diet consists of small gastropod mollusks, isopods, amphipods and ostracods, most of which can be found in or within close proximity to the lobster’s algal shelter. 

Aggressive behavior between juvenile lobsters has been observed as a means of enforcing territoriality.  The consequence of increased aggressive interactions as well as a declining food source is hypothesized to induce the nomadic emigration from the algal nursery environment to the off shore reef.  

Adult and juvenile phase lobsters spend daylight hours existing inactively in shelters and emerge in the evening to forage for food.  Adult lobsters are key predators in many benthic habitats, their diets consisting of slow-moving or stationary bottom-dwelling invertebrates including sea urchins, mussels, gastropods, clams and snails.  Spiny lobster is preyed upon by larger animals such as sharks and finfish. Evening movements away from and subsequent return to their dens illustrates the acute spatial orientation possessed by this species.  

## Growth

*Figure 4*
- Puerulus and early juvenile (post-puerulus) phases

## Molting

*Figure 5*
- Spiny lobster in mid-molt

**Notes:**
Physical growth of the Caribbean Spiny lobster is achieved through molting. The molt cycle begins with the intermolt period, the time when a new cuticle is being created, tissue growth is rapid and the lobster actively forages.  This period of time culminates in ecdysis, which is shedding the old cuticle.  Adult lobster molt an average of about two and a half times each year.  The entire molting event takes approximately ten minutes.  The new exoskeleton takes about 12 days from the start of the molt to harden such that it cannot be dented, however the shell is not completely formed until the 28th day.  

Studies found that feeding rates significantly increase in the time preceding a molt to accommodate the increasing metabolic needs associated with new cuticle formation.  About a week before ecdysis, daily food intake for the Caribbean spiny lobster decreases rapidly, in correlation with a reduction in demanding activities such as locomotion and foraging.  In the few days before and the time during ecdysis, feeding ceases altogether and the lobster becomes socially reclusive.  Within a week of the molting event, P. argus will display maximal feeding, foraging and locomotor activity rates to accommodate for the active tissue growth that occurs (Lipcius and Hernkind, 1982).  The dramatic swings in feeding and foraging behavior associated with the molting cycle influences the success of fishermen when capturing this species.  The highest catchability of spiny lobster is expected immediately following molting because lobsters are actively foraging at this time and will therefore be more likely to accept bait.  Conversely, the lowest catachability of spiny lobster is expected before molting when foraging decreases and the lobster becomes less mobile (Lipcius and Hernkind, 1982). 

## Von Bertalanffy Growth Curves for Spiny Lobster

*Figure 6*
- L = Linf [1-e(-k(t-to))]

**Notes:**
Despite the wide body of literature on this species, limited information is available on the growth of P. argus due in part to the molting habits of lobsters interfering with tagging efforts.  Some of the data that is available, however has been compiled in this figure to show growth curves at different locations for spiny lobster based on parameters collected from Jamaica, the U.S. Caribbean and Cuba.

## Natural Mortality

***Figure 7***
**   ****Location 1:  South Jamaica Shelf, M & F****	****	****Location 5:  Port Royal Reefs, Jamaica, M & F**
**   ****Location 2:  Pedro Cays area, Jamaica, M & F ****	****Location 6:  Northern Fishing Grounds, Bermuda, M**
**   ****Location 3:  Argus Bank, Bermuda, M****	****	****Location 7:  Northern Fishing Grounds, Bermuda, F**
**   ****Location 4:  Argus Bank, Bermuda, F**

**Notes:**
Similarly, few reports contain information on the natural mortality of this species due to the difficulty in separating natural and fished mortality rates.  The data reflected in this chart, gives examples of natural mortality rates for seven different locations, four that experienced light fishing pressure and three that experienced severe fishing pressure.  
South Jamaica shelf
Pedro Cays area, Jamaica
Argus bank, Bermuda males
Argus bank, Bermuda females
Port Royal Reefs, Jamaica
Northern fishing grounds, Bermuda males
Northern fishing grounds, Bermuda females

## Reproduction

*Figure 8*
- Female with gray spermatophore mass

**Notes:**
Reproduction in the Caribbean spiny lobster occurs almost exclusively in the deep reef environment once mature individuals have made the permanent transition from the shallow seagrass nursery.  Spawning season is in the spring and summer, however autumnal reproduction has been known to occur in some situations.  The gestation period for eggs is about a month.  The eggs are colored orange when they are fresh, and brown when they are close to hatching.  Studies have found that the initiation of spawning is related to water temperature and the optimal water temperature for mating is 24 degrees centigrade. 

Choice of mate is determined by the female as well as inter-male aggression, where larger males will prevent a smaller male from courting a female.  Females mate only once during a season, while males can fertilize multiple females.  During mating, the male and female each stand on their hind walking legs while the male deposits the spermatophore mass on the female’s sternum.  

Larger adult females will produce more broods, as well as spawn eggs earlier in the reproductive period than younger females since younger individuals molt earlier in the reproductive period. 

## Reproductive Potential

*Table 1*
**Reproductive potential for female *****Panulirus argus*** **in Upper and Middle Florida Keys (Lyons, et. al., 1981).**

**Notes:**
As I mentioned, Reproductive fecundity is dependent upon the size of the individual as well as the geographic area in which the lobster lives.  Reproductive potential for a given size in a given area can be determined using the relationship between fecundity and carapace length.  A study done in South Florida revealed a difference in the size of mature individuals between the Upper and Middle Florida Keys..........(change slide)

## Reproductive Potential

*Table 2***Reproductive potential for female *****Panulirus argus***** in Dry Tortugas Protected Area (Lyons, et. al., 1981).**

**Notes:**
.....and the Dry Tortugas.  Generally speaking, spawning seems to begin when individuals reach carapace lengths of around 70mm while spawning declines at lengths greater than 130mm.  Maximum reproductive capacity is achieved at sizes between 100 and 130 mm in carapace length.

## Index of Reproductive Potential

*Figure 9*
- Difference in reproductive potential between two different locations

**Notes:**
This graph represents the indices of reproductive potential as calculated from the data and illustrates the potential differences that can occur in reproductive potential from one location to another.  The model computes the contributions to total egg production by females of different size classes, using incidence and egg-carrying capacity of each size class.  

(The constant 233.8 was computed to set the 76-80cm carapace length at 100 to use as a standard since the greatest number of females fell into this size category).  

## Mass Migration

*Figure 10*
- Queuing behavior of spiny lobsters.

**Notes:**
Mass migrations of two to 60 individuals to deeper water locations occurs annually throughout the geographic range of the species and are dependent on latitude and climactic factors.  Observed locations for the migration include Bermuda in October, the Bahamas and Florida in late October and early November, and the Yucatan and Belize in December.  This mass migratory behavior is hypothesized by some to have evolved in response to deteriorating conditions resulting from the periods of glaciations that occurred over the past several 100,000 years.  Migration will begin after the first autumn storm occurs in the tropics, typically bringing a severe drop in water temperature of about five degrees centigrade, as well as high northerly winds of up to 40km/h and large sea swells.  Lobsters initiate the migratory behavior by queuing, the single file formation of migrating individuals accomplished by visual or tactile stimuli.  Queuing is maintained by establishing contact between the antennules of one individual and anterior walking legs of another. Biologically, the queuing behavior is an important hydrodynamic drag reduction technique for the migration of individuals long distances.  

Hopefully that has given you all a general overview of the biology of this species...if you have any questions I would be happy to try and answer them now.