Panulirus Penicillatus Research Articles

After the gold rush: population structure of spiny lobsters in Hawaii following a fishery closure and the implications for contemporary spatial management

We compared mitochondrial genetic data for two spiny lobsters in Hawaii with different geographic ranges and histories of fishing pressure. Panulirus marginatus (Quoy and Gaimard, 1825) is endemic to Hawaii, and experienced a short, intense fishery in the Northwestern Hawaiian Islands (NWHI) and long-term, less intense exploitation in the Main Hawaiian Islands (MHI). Populations show significant overall structure (F ST = 0.0037, P = 0.007; D est_Chao = 0.137), with regional differentiation (F CT = 0.002, P = 0.047) between the MHI and the NWHI. Haplotype diversity did not differ significantly between regions (F2, 8 = 3.740, P = 0.071); however, nucleotide diversity is significantly higher at the primary NWHI fishery banks (0.030) than in the MHI (0.026, Tukey's P = 0.013). In contrast, Panulirus penicillatus (Olivier, 1791), found across the tropical Indo-West Pacific region, was not targeted by the NWHI fishery, but has experienced long-term exploitation in the MHI. Panulirus penicillatus has no significant overall population structure in Hawaii (F ST = 0.0083, P = 0.063; D est_Chao = 0.278), although regional differentiation (F CT = 0.0076, P = 0.0083) between the MHI and the NHWI is significant. Neither haplotype nor nucleotide diversity differed significantly between regions for P. penicillatus While neither species has suffered a loss of genetic diversity from fishing, our results highlight that only by incorporating knowledge of fishing history with genetic connectivity data can we understand the most beneficial management strategy for each species. Neither exemplar species nor specific suites of traits are reliable predictors of the spatial scales of management.

Pacific Ciguatoxins in Food Web Components of Coral Reef Systems in the Republic of Kiribati

Ciguatera fish poisoning (CFP) is a foodborne illness caused by consumption of coral reef fishes contaminated by ciguatoxins (CTXs); of the known CTX congeners, the Pacific ciguatoxins (P-CTXs) are the most toxic. Little is known about the trophodynamics of P-CTXs in coral reef systems. The present study explores the distribution, transfer, and trophic magnification of P-CTX-1, -2, and -3 in coral reef systems with high (ciguatoxic) and low (reference) ciguatoxicity in a CFP-endemic nation by use of liquid chromatography-tandem mass spectrometry (LC-MS/MS). In ciguatoxic coral reef systems, P-CTXs were detected in 54% of herbivorous fishes [total P-CTXs <0.500-1670 pg/g wet weight (ww)], 72% of omnivorous fishes (<0.500-1810 pg/g ww), and 76% of carnivorous fishes (<0.500-69 500 pg/g ww), as well as a lobster ( Panulirus penicillatus ; 2.36 pg/g ww) and an octopus (Octopodidae; 2.56 pg/g ww). The dominant P-CTXs in grazers and piscivorous fishes were P-CTX-2 and -1, respectively. No significant correlation between P-CTX levels and lipid content in three target predatory fishes indicated that accumulation of P-CTXs does not depend on fat content. A weak but significant positive relationship was observed between δ(15)N and P-CTX-1 levels, but further investigation is required to confirm its biomagnification potential.

Complexities of fisheries and fisheries research: A comment on “Behavior of the Galapagos fishing fleet and its consequences for the design of spatial management alternatives for the red spiny lobster fishery” by . doi:10.1016/j.ocecoaman.2013.03.001

A recent study (Bucaram et al., 2013) provides a contribution on the behavior of the Galapagos fishing fleet for spiny lobster (Panulirus penicillatus and P. gracilis). This comment supplements that study by resolving some gaps in its understanding of existing knowledge on the structure and dynamics of Galapagos fisheries. Specifically, we highlight the literature already available on Galapagos fishing behavior, the breadth and impact of the participatory process contributing to the Galapagos fishery co-management framework, and the relevance of previous fishery policy recommendations. As highlighted in this published literature, there is a need for further studies of fishing behavior in the Galapagos Islands; such studies can be of greatest benefit by building on the current knowledge base on fishing behavior and its management implications.

Behavior of the Galapagos fishing fleet and its consequences for the design of spatial management alternatives for the red spiny lobster fishery

The two most profitable fisheries in the Galapagos Islands, red spiny lobster (Panulirus penicillatus) and sea cucumber (Isostichopus fuscus), are facing steep declines in abundance and may be on the verge of collapse. This state of affairs has emerged in part because of command and control fisheries policies that neglected the importance of the behavior of the fishing fleet itself. Here we attempt to describe and explain the factors influencing the fishing behavior of the Galapagos red spiny lobster fishing fleet. We estimated a set of econometric models based on a random utility maximization process to forecast how changes in the immediate circumstances (economic, biological, climatic and oceanographic) impact voluntary fishing choices via the personal costs and benefits of various decisions. We focused on the factors that affect not only the decision to participate in fishing but also the decision of where to fish. We then use these models to determine the revenue elasticities for each fishing zone and to analyze the overall response of the Galapagos fleet to hypothetical closures of fishing zones. Our results provide some empirical benchmarks from which it is possible to identify in advance problems related to the spatial management of the red spiny lobster fishery and their potential solutions. For example, we found that fisherman from San Cristobal Island have a strong preference for fishing sites on Floreana Island, which is geographically closer to Santa Cruz Island. This could lead to conflicts between the San Cristobal and Santa Cruz fishing fleets if rights-based fishery management were implemented. We expect that our analysis will be valuable to policy makers when designing new types of management plans for Galapagos fisheries.

Genetic Isolation between the Western and Eastern Pacific Populations of Pronghorn Spiny Lobster Panulirus penicillatus

The pronghorn spiny lobster, Panulirus penicillatus, is a circumtropical species which has the widest global distribution among all the species of spiny lobster, ranging throughout the entire Indo-Pacific region. Partial nucleotide sequences of mitochondrial DNA COI (1,142–1,207 bp) and 16S rDNA (535–546 bp) regions were determined for adult and phyllosoma larval samples collected from the Eastern Pacific (EP)(Galápagos Islands and its adjacent water), Central Pacific (CP)(Hawaii and Tuamotu) and the Western Pacific (WP)(Japan, Indonesia, Fiji, New Caledonia and Australia). Phylogenetic analyses revealed two distinct large clades corresponding to the geographic origin of samples (EP and CP+WP). No haplotype was shared between the two regional samples, and average nucleotide sequence divergence (Kimura's two parameter distance) between EP and CP+WP samples was 3.8±0.5% for COI and 1.0±0.4% for 16S rDNA, both of which were much larger than those within samples. The present results indicate that the Pacific population of the pronghorn spiny lobster is subdivided into two distinct populations (Eastern Pacific and Central to Western Pacific), with no gene flow between them. Although the pronghorn spiny lobster have long-lived teleplanic larvae, the vast expanse of Pacific Ocean with no islands and no shallow substrate which is known as the East Pacific Barrier appears to have isolated these two populations for a long time (c.a. 1MY).

Modelling the growth of crustacean species

Crustaceans play an important role in marine ecosystem and worldwide fisheries. Accurate and quantitative description of growth is crucial in modelling the demographics and fisheries stock assessment. The stepwise growth as a result of the moulting process and the lack of permanent calcified structures make the traditional approaches developed for finfish inappropriate for crustaceans. This study reviews the data collection, quantitative methods and various sources of uncertainty for modelling the growth of crustacean. The methods were reviewed based on their data requirement and mathematical/statistical complexity ranging from simple growth rate, continuous growth curve to stepwise growth curve and size transition matrix. A comparative example of different growth models was illustrated with four selected crustaceans: American lobster (Homarus americanus, Nephropidae), Dungeness crab (Metacarcinus magister, Cancridae), blue crab (Callinectes sapidus, Portunidae) and pronghorn spiny lobster (Panulirus penicillatus, Palinuridae). Model selection and multi-model inference based on the information theory was discussed for modelling the growth components of moutling increment and intermoult period. Various drivers in determination of the growth pattern of crustaceans were evaluated, including life history strategy and environmental stress. The incorporation of environmental factors into the development of growth models and the recent progress in age-determination were highlighted. We discussed possible research needs for better quantification of crustaceans growth.

Incorporating climate changes into population dynamic modelling: an individual-based modelling approach for lobster

One of the most challenging issues in fisheries management is the evaluation of the effects of fishing in the context of a changing environment. Using the pronghorn spiny lobster ( Panulirus penicillatus ) fishery off the eastern coast of Taiwan as an example, we developed an individual-based model (IBM) that is capable of describing the temperature-dependent life history processes and fishery practices for the spiny lobster. We then used the model to evaluate potential impacts of increased ocean temperature on the estimation of mortality-based biological reference points for fisheries management. We demonstrate that a warming temperature would increase the yield-per-recruit and eggs-per-recruit values and consequently reduce the risk of overexploitation under the current exploitation level. However, there is likely a high risk of overexploitation in the long term if higher temperatures induce extra-high natural mortality. The evaluation of effectiveness of size regulations suggests that increasing minimum legal size is proposed as a good candidate measure to reduce the risk of overexploitation for pessimistically unfavorable environmental conditions. This study suggests that an explicit incorporation of the relationships between environmental variables and biological processes can greatly improve fisheries assessment and management.

Ecological determinants and sensory mechanisms in habitat selection of crustacean postlarvae

Animals use sensory stimuli to assess and select habitats, mates, and food as well as to communicate with other individuals. One of the great mysteries of crustacean ecology is how postlarvae locate the relatively rare patches of coral reef habitat on which they settle. The present study aimed to estimate, by experiments in aquaria and biochemical analysis, the sensory modalities of crustacean postlarvae for senses used in searching for their species' settlement habitat. The study was carried out on 9 crustacean species (Calappa calappa, Pachygrapsus planifrons, Xanthidae sp., Lysiosquillina maculata, L. sulcata, Raoulserenea sp., Stenopus hispidus, Palaemonidae sp., and Panulirus penicillatus). For each species, a cohort of 30 postlarvae was captured on the same night on the reef crest of Rangiroa Atoll (French Polynesia). Among the 9 crustacean species studied, 6 made active habitat choices among the 4 habitats tested (live coral, dead coral, macroalgae, and sand) at the postlarval stage, but the presence or absence of conspecifics on the habitat did not influence their selective choice. Sensory experiments found that 4 species differentiated between their preferred habitat versus another habitat and 2 species differentiated between conspecifics and heterospecifics, using visual and/or olfactory cues. Lastly, the high performance liquid chromatography experiments showed that the 4 habitats and conspecifics (except L. maculata and S. hispidus) tested have different and unique chemical odors. Overall, our study is the first to highlight the sensory modalities for a broad range of crustacean species to detect and move toward settlement habitats and/or conspecifics.

Incorporating uncertainty into the estimation of biological reference points for a spiny lobster (Panulirus penicillatus) fishery

The status of a fishery is often defined as the probability of fishing mortality rate exceeding a perilous level for long‐term sustainability. Lobster stock assessments are often subject to large uncertainty in input data and high levels of natural variability in lobster life history processes, which calls for incorporating uncertainty associated with both indicator and management reference points in an evaluation of biological risk of overfishing. Using a Monte Carlo simulation approach, we evaluated the impacts of uncertainty in modelling on the determination of the status of the Taitung spiny lobster (Panulirus penicillatus) fishery (Taiwan), which has not been quantitatively determined despite its commercial importance. The commonly used biological reference points derived from the per recruit model (F 0.1 the fishing mortality rate where the slope of the curve of yield‐per‐recruit model is 10% of the maximum slope and F 4Q%, the fishing mortality rate that reduces the expected egg production for a cohort of female lobsters to 40% of that produced in the absence of a fishery of the egg‐per‐recruit model) were influenced by uncertainties associated with lobster life history and fishery parameters. A large uncertainty in the current fishing mortality rate (F cnr) and estimates of biological reference points (F BRPs) increased the uncertainty in determining the risk of overexploitation throughout the confidence levels of the stochastic decision‐making framework. This simulation study suggests that the target reference point of F 40% is less sensitive to the input parameters’ uncertainty than F 0.1 We suggest a further evaluation of other F‐based references points and development of biomass‐based reference points before final selection and implementation for the management of the Taitung lobster fishery.

Cascading effects of fishing on Galapagos rocky reef communities: reanalysis using corrected data

This article replaces Sonnenholzner et al. (2007; Mar Ecol Prog Ser 343:77-85), which was retracted on September 19, 2007, due to errors in entry of data on sea urchins. We sampled 10 highly fished and 10 (putatively) lightly fished shallow rocky reefs in the southeastern area of the Galapagos Marine Reserve, Ecuador. After the correction, these are the new results: there was a negative association between slate-pencil urchins Eucidaris galapagensis and non-coralline algae. In addition, pencil urchins were less abundant where there were many predators. An indirect positive association between predators and non-coralline algae occurred. Fishing appeared to affect this trophic cascade. The spiny lobster Panulirus penicillatus, the slipper lobster Scyllarides astori, and the Mexican hogfish Bodianus diplotaenia were significantly less abundant at highly fished sites. Urchin density was higher at highly fished sites. Non-coralline algae were nearly absent from highly fished sites, where a continuous carpet of the anemone Aiptasia sp. was recorded, and the algal assemblage was mainly structured by encrusting coralline and articulated calcareous algae.

Life History of the Red Spiny Lobster, Panulirus penicillatus (Decapoda: Palinuridae), in the Galápagos Marine Reserve, Ecuador1

The red spiny lobster, Panulirus penicillatus (Olivier, 1791), is exploited commercially in the Galapagos Marine Reserve by the local fishing sector. Catches and catch per unit effort have declined over the past few years, leading to concerns about sustainability of the fishery. This study supports the processes regarding the fishery management of P. penicillatus by determining its distribution and growth parameters. Nearly 3,000 lobsters were tagged during surveys carried out at 13 islands between 2000 and 2004. Sex ratio did not differ significantly from 1 : 1, and tagging returns showed little or no movement of individuals. Mean values with 95% confidence intervals for von Bertalanffy growth parameters were estimated to be K = 0.201 ± 0.004, L ∞ = 16.91 ± 0.183 (cm carapace length), and Φ′ = 4.14 ± 0.019 for males; and K = 0.264 ± 0.02, L ∞ = 12.34 ± 0.40 (cm carapace length), and Φ′ = 4.99 ± 0.06 for females. Natural mortality was 0.342 for males and 0.378 for females. These results, together with comparative estimates for red spiny lobster elsewhere, illustrate the geographical variability of growth among populations of P. penicillatus, which may occur within the archipelago itself.

Microbial diversity of mid-stage Palinurid phyllosoma from Great Barrier Reef waters

This study aimed to determine the bacterial community associated with wild-caught, mid-stage larvae of spiny lobsters (Palinuridae) in their native oligotrophic marine environment, and to compare their diversity and composition with communities associated with aquaculture-reared larvae of the tropical rock lobster Panulirus ornatus. Bacterial clone libraries constructed from wild P. ornatus (two libraries) and Panulirus penicillatus (one library) larvae (phyllosoma) revealed a dominance of alpha-proteobacterial sequences, with Sulfitobacter spp.-affiliated sequences dominating both P. ornatus libraries and constituting a major portion of the P. penicillatus library. Vibrio-related sequences were rarely detected from wild phyllosoma clone libraries in contrast to similar studies of aquaculture-reared animals. Scanning electron microscopy analysis revealed low levels of bacterial colonization on the external carapace of wild phyllosoma, again in contrast to aquaculture-reared animals, which are often colonized with filamentous bacteria (mainly Thiothrix sp.) that compromise their health. Fluorescence in situ hybridization of sectioned wild phyllosoma tissue displayed low overall abundance of bacteria within the tissue and on external surfaces, with alpha-, beta-, and gamma-Proteobacteria being confirmed as members of this bacterial community. The consistency in predominant clone sequences retrieved from the three libraries indicated a conserved microbiota associated with wild phyllosoma. In addition, the observed differences in the microbial composition and load of reared and wild phyllosoma are indicative of the different environments in which the animals live. Bacterial disease during early larval stages is a major constraint currently hindering the development of an aquaculture industry for the ornate rock lobster P. ornatus. Knowledge of the microbial community associated with wild animals will be advantageous for the identification of bacteria that may promote animal health.

Cascading effects of fishing on Galapagos rocky reef communities

A replicated comparison of heavily and lightly fished areas in the Galapagos suggested that fishing predators led to an increase in herbivores and a dramatic shift in the algal community toward crustose barrens. We sampled 10 highly fished and 10 lightly fished shallow rocky reefs in the southeastern area of the Galapagos Marine Reserve, Ecuador. Negative associations between con- sumers and resources suggested top-down control. At cold sites, there was a negative association between slate-pencil urchins Eucidaris galapagensis and non-coralline algae. In addition, at cold sites, pencil urchins were less abundant where there were many predators. An indirect positive asso- ciation between predators and non-coralline algae occurred at warm and cold sites. Fishing appeared to affect this trophic cascade. The spiny lobster Panulirus penicillatus, the slipper lobster Scyllarides astori, and the Mexican hogfish Bodianus diplotaenia were significantly less abundant at highly fished sites. Urchin density was higher at highly fished sites. Non-coralline algae were nearly absent from highly fished sites where a continuous carpet of the anemone Aiptasia sp. was recorded and the algal assemblage was mainly structured by encrusting coralline and articulated calcareous algae.

Reproductive biology of the spiny lobster, Panulirus Penicillatus, in the southeastern coastal waters off Taiwan

The reproductive biology of spiny lobster, Panulirus penicillatus, was studied based on 2,068 lobsters, ranging from 34.28 to 131.60 mm carapace length (CL), sampled in Taitung coastal waters from September 2003 to December 2004. The overall sex ratio approximated 1:1 (χ2 = 0.02, P > 0.05), but the monthly sex ratios in 2004 showed significant differences and males were predominant in sizes larger than 80 mm CL. Reproductive activity, assessed using histology, a gonadosomatic index and percentage of ovigerous females, indicated that the mature females could be found in every month and that the major spawning occurred from May to September. The presence of re-developing/re-ripe ovaries by month and size-specific spawning time suggest that larger mature females (>60 mm CL) spawn at least three times a year while smaller new mature females spawn at least once a year. For females, the estimated sizes at 50% physiological and functional maturity were (mean ± SE) 56.46 ± 0.56 mm CL and 66.63 ± 1.07 mm CL. The estimated sizes at functional maturity were between 72 and 74 mm CL for males. The number of eggs per spawning event (brood size, BS) was related to CL by the equation YBS = 2.4 × 10-3CL4.18 (r2 = 0.902, n = 12). Female lobsters with CL ranging from 60 to 80 mm made the greatest contributions to egg production because of their high brood size and active reproductive activity. A minimum legal size should be established for the fishery to protect egg production potential of lobster population in the southeastern coastal waters off Taiwan.

The Complete Larval Development of the Pronghorn Spiny Lobster Panulirus Penicillatus (Decapoda: Palinuridae) in Culture

The ability to culture larval lobsters is of paramount importance to the commercial development of effective aquaculture methods. Recently, we developed two separate laboratory culturing strategies that yielded the complete larval development from egg to puerulus (post-larva) for the commercially important and transpacific Pronghorn spiny lobster, Panulirus penicillatus (Olivier, 1791). Individual phyllosomal culture of 10 newly hatched animals was carried out in a static seawater system. Two of the 10 phyllosomata held at |$24.5{\text{-}}26.0^\circ {\text{C}}$| metamorphosed after 22 molts to the puerulus stage at 256 and 294 days respectively (⁠|${\text{final body lengths}}\, = 30.80\, {\text{mm}}$| and |$32.00\, {\text{mm}}$|⁠). Mass culture of 500 newly hatched phyllosomata was also carried out in two specialized acrylic flow-through seawater tanks. Of the 500 larval animals, 215 were randomly sampled and morphologically staged (10 distinct stages were observed and documented as well as two sub-stages). Seven phyllosomata that were mass cultured metamorphosed to the puerulus stage under a constant temperature regime of |$24^\circ {\text{C}}\,({\text{mean days}} = 302.4$| and |${\text{mean final body length}} = 32.133\, {\text{mm}}$|⁠). This species is now one of eight palinurid lobsters and only the fourth Panulirus spp. to be cultured completely from hatch to settlement stage. The biological understanding of larval development for this species promotes the feasibility for aquaculture and potentially facilitates future modeling of larval dispersal and duration in the field.

GROWTH AND MINIMUM SUITABLE CATCH SIZE OF SPINY LOBSTERS, PANULIRUS PENICILLATUS (OLIVIER, 1791) AND PANULIRUS LONGIPES BISPINOSUS BORRADAILE, 1899 (DECAPODA, PALINURIDAE) IN THE SOUTHERN LAGOON OF NEW CALEDONIA

Panulirus penicillatus and Panulirus longipes bispinosus are the main species of spiny lobsters caught by commercial fishermen in the New Caledonian lagoon. The growth of the males and females of these two species is described by a Von Bertalanffy curve based on observing growth in captivity and in the field, and according to the statistical analysis of cephalothoracic length-frequency histograms obtained from commercial catches. A minimum suitable catch size has been calculated from the study of the males of P. penicillatus, which have the most rapid growth. For practical reasons, due to the artisanal frame of this fishery, this limit size (Cephalothorax Lengthlim = 7.5 cm) is recommended for both species and both sexes.

Detection of white spot syndrome associated baculovirus in experimentally infected wild shrimp, crab and lobsters by in situ hybridization

The techniques of detecting white spot syndrome associated baculovirus (WSBV) by in situ hybridization are already well established. A DNA probe specific to PmNOB III, an isolate of WSBV from Penaeus monodon, was labeled with digoxigenin and used to detect WSBV DNA in experimentally infected wild shrimps, crabs and lobsters that are native to Taiwan. WSBV could be detected in tissue sections of all examined specimens by in situ hybridization. In marine shrimps, Trachypenaeus curvirostris, Metapenaeus ensis and Exopalaemon orientalis, WSBV DNA positive cells were observed in the gills, stomach, cuticular epidermis, antennal gland, hepatopancreas, compound eye, muscle, heart and reproductive tissues. WSBV DNA was observed only in the gills, cuticular epidermis and hepatopancreas in the freshwater shrimps Macrobrachium sp. and Procambarus clarkii. In crabs Portunus sanguinolentus and Charybdis granulata, WSBV DNA could be detected in the gills, stomach, hepatopancreas, muscle and reproductive tissues. In lobsters Panulirus versicolor and Panulirus penicillatus, the positive cells were observed in the gills, stomach, cuticular epidermis and hepatopancreas.

Size distribution, maturity and fecundity of the spiny lobsterPanulirus penicillatus(Olivier 1791) in the Red Sea

Panulirus penicillatus (Olivier 1791), although widely distributed and locally abundant, is a relatively little known species of spiny lobster. Lobsters (n = 355) were caught by trapping in the Saudi Red Sea between Port Sharma and Yanbu. For a subsample of 60 of these, measurements were made of carapace length (CL), length of 2nd and 3rd pereiopods, and the number of eggs carried by ovigerous females. The allometric relationship between CL and the lengths of the second and 3rd pereiopods differs after sexual maturity, and between males and females: allometry of leg length can therefore be used to estimate the size of sexual maturity. Saudi P. penicillatus appear to mature at carapace lengths of 40–50 mm. The relationship between CL and egg number is given by the equation E = 7.43 (CL)2,30. Size distribution and fecundity were combined to indicate the relative contribution to reproduction of different size classes. In both size distribution and size-specific fecundity, the Saudi Red Sea population studied...

Sexual maturity, reproductive season and fecundity of the spiny lobster Panulirus penicillatus from the Gulf of Eilat (Aqaba), Red Sea

Panulirus penicillatus Olivier (1791) (Decapoda: Palinuridae) is widely distributed in the Indian and Pacific Oceans and is the most common spiny lobster in the Red Sea. Female lobsters (n =234), were collected on four occasions in 1986 from the coral reef of Dahab, 110 km south of Eilat, Israel. Field data and the gonadal index indicated that the reproductive season was from February to October, during which the females spawned 2-4 times. In nature, females became sexually mature at a carapace length (CL) of 50 mm. This result was confirmed by morphometric analysis of the regression between pleopodal exopodite length and carapace length. The number of eggs per spawn (E) was related to CL by the equation E=2.715 ×(CL)2.581. The incubation period of eggs was 35.5�1.0 days (�s.d.) at temperatures of 24-27�C in the aquarium. The results are compared with data on P. penicillatus from other parts of its geographic range, and the effect of geographic isolation on reproduction is discussed.

Population structure and growth in captivity of the spiny lobsterPanulirus penicillatus from Dahab, Gulf of Aqaba, Red Sea

Panulirus penicillatus (Olivier, 1791) (Decapoda: Palinuridae) is the most common spiny lobster in the Red Sea and is widely distributed in the Indian and Pacific Oceans. Lobsters (n=377) were collected on four occasions during 1986 on the coral reef at Dahab, Sinai, Egypt. Average size of the collected individuals was 70.5±24.6 mm carapace length (CL) for males and 63.2±15.9 mm CL for females. The sex ratio was 1:1.64 males to females. Length increment per molt was inversely correlated with size and ranged from 2.1 mm per molt in the 40 to 50 mm CL size class to less than 1 mm in the 60 to 70 mm CL size class. Average intermolt period was ca. 136 d for all size classes. The relationship between carapace length and body weight was expressed by the equation:Wb=6.43 × 10−4 × (CL)2.89.P. penicillatus from Dahab differ in size, sex ratio and growth rate compared to other palinurid populations throughout their range. This might represent the effect of isolation and location at the edge of the geographical range for this species. It may also indicate an adaptation to their unique habitat in the coral reef in comparison to other palinurid species.