Panulirus Ornatus Research Articles

The Periodic Feeding Frequency of the Juvenile Tropical Rock Lobster (Panulirus ornatus) in the Examination of Chemo-Attract Diet Performance and Colour-Contrast Preference.

Significant research investment into tropical rock lobster (TRL) aquaculture production methods has led to a rapidly developing industry in Vietnam and, more recently, in Australia. The need for an effective formulated feed has been highlighted for both industries; however, feed intake has been a consistent limitation. Visual and chemical cues regulating feed recognition and consumption are expected to yield valuable data, leading to increased feed intake. Lobsters were placed in white- and grey-coloured enclosures to examine the effect of background colour on their feeding behaviour in terms of feeding occurrence and response time. The impact of background colour on TRL feeding behaviour found no statistically significant differences between TRL in white and grey enclosures, suggesting grayscale contrast does not directly affect feeding behaviour. Experiment 2 studied the effects of coloured feeding zones on feeding response in white enclosures. Yellow feeding zones led to a decreased feeding time (473 ± 443 s) and increased time spent feeding (168 ± 1832 s) compared to other colours, possibly due to the yellow-blue chromaticity (b*) contrast. Experiment 3 examined chemo-attractants (glycine, taurine and inositol) and their influence on the feeding behaviour of TRL, but no increased responses were observed. Experiments two and three assessed TRL feeding activity in morning and evening periods, highlighting their nocturnal behaviour, with more feeding occurring in the evening. This project enhances our understanding of photoreceptive and chemoreceptive factors affecting TRL feeding behaviour with formulated feed. It also reveals the potential for background colour changes to enhance marketable colours in commercial settings. Additionally, the study confirmed the effective use of animal tracking software (EthoVision XT) for lobster species tracking in future behavioural trials.

Changes in the physiology and chitin metabolism in cultured juvenile Panulirus ornatus across the moult cycle

Crustaceans undergo periodic moulting events to facilitate growth, this is a physiological and energetically demanding process. In an aquaculture environment, crustaceans are generally cultured in a defined space and often at high densities, where exposure to cannibalism may be greater than in the wild. Panulirus ornatus is one such emerging aquaculture candidates, moulting frequently as juveniles and providing the opportunity to investigate the relationship between physiology and genetics throughout this important developmental period. In this study, P. ornatus juveniles were assessed every three days across the seventh to eighth juvenile moult phase, sampling was divided into six distinct time points. Brix index, hepatosomatic index, and circulating ecdysone concentrations were measured across these time points. The Brix index was validated as a useful tool for assessing the moult-stages of juvenile P. ornatus, with an increase in Brix value seen in the lead up to ecdysis. Chitin metabolism was mapped, with Chitinase 3 demonstrating hepatopancreas specificity, indicating a role outside of breakdown of dietary chitin. The investigation of physiological parameters across a moult cycle provides a basis for improving moult cycle staging in cultured P. ornatus juveniles and provides further characterisation of the changes that occur during moulting in this species.

Functional morphology and ontogeny of mouthparts and mouth aperture of Panulirus ornatus and Sagmariasus verreauxi: Implications towards formulated feeds development

Development of formulated feed is now a focal point in advancing the aquaculture of spiny lobster species. This study investigated the functional morphology of two spiny lobsters, Panulirus ornatus and Sagmariasus verreauxi, by analysing mouthpart morphology and mouth aperture. The analysis is focussed on determining likely feed preference based on morphology with the aim to provide knowledge for the development of formulated feeds. There is a strong correlation between the mouth aperture being approximately 4.0 and 7.5% of the carapace length of S. verreauxi and P. ornatus juvenile and adult lobsters, respectively. This finding provides knowledge for development of a species-specific tool that could be used in experimental studies to define optimal dimensions of artificial manufactured pellets in relation to the size of the lobster. Differences in mouthpart morphology through ontogeny included increase of calcification and robustness, and this is likely to reflect a different requirement in the texture (softness/hardness) of the pellet as the animals develop. Spines and setation are a prominent feature of the mouthpart morphology and differ between species and during ontogeny. Spines on maxillipeds II and III and crista dentata on maxillipeds III are likely to play an important role in holding and manipulation of feed prior to ingestion. Pellet texture may need to accommodate these differences in species and age specific mouthpart ontogeny. Ontogenetic changes in setation were found, with much richer setation proportionally to the size of mouthpart in first instar juvenile lobsters, which decreases with size increase. Furthermore, species-specific differences indicate function shifts in mouthparts with life stages. This may indicate differences in filter feeding capacity with age and between species, as reported for other decapods. This is unlikely to be of high importance in pellet feeding but may represent an avenue of investigation for first feeds in juveniles. Collectively, the differences during ontogeny and between species suggest that formulated feeds may need to be tailored to species and life stage, particularly regarding pellet dimensions and texture.

Effect of Dietary Protein to Energy Ratios on Growth, Digestive Enzyme Activity and Body Composition of Captive Juvenile Spiny Lobsters, Panulirus Ornatus (Fabricius, 1798)

Abstract An evaluation of six dietary protein-to-energy (P/E) ratios was conducted to the early juvenile lobsters (Panulirus ornatus) by investigating the ratio effects on physiology, digestive enzyme activities, body composition, and amino acid profiles. Juvenile lobsters (0.25±0.01 g) were individually kept in aquaria and treated with six isoenergetic formulated diets of P/E ratios of 21.8, 22.5, 23.5, 24.6, 25.3 and 26.6 mg KJ–1. After 8 weeks of feeding experiment, the differentiation on dietary P/E ratios was found to have affected the specific growth rates, but not the survival, moult increment, moulting rate, moult interval and average daily moulting rate of juvenile lobsters. The dietary P/E ratio also influenced the protease, lipase, superoxidase dismutase activities, and body composition of juvenile lobster. The increase in dietary protein levels significantly affected the increase of the specific growth rate, while increased dietary lipid levels only affected the length increments. Both protein and lipid content were found in the whole body of the juveniles which reflected the treated dietary composition. Results indicated that a P/E ratio of 26.6 mg KJ–1 (55% dietary protein and 9% dietary lipids) can yield the maximum growth and digestive enzyme activities from among the studied diets.

Chromosome-level genome of the long-tailed marine-living ornate spiny lobster, Panulirus ornatus

Recent conservation efforts to protect rare and endangered aquatic species have intensified. Nevertheless, the ornate spiny lobster (Panulirus ornatus), which is prevalent in the Indo-Pacific waters, has been largely ignored. In the absence of a detailed genomic reference, the conservation and population genetics of this crustacean are poorly understood. Here, We assembled a comprehensive chromosome-level genome for P. ornatus. This genome—among the most detailed for lobsters—spans 2.65 Gb with a contig N50 of 51.05 Mb, and 99.11% of the sequences with incorporated to 73 chromosomes. The ornate spiny lobster genome comprises 65.67% repeat sequences and 22,752 protein-coding genes with 99.20% of the genes functionally annotated. The assembly of the P. ornatus genome provides valuable insights into comparative crustacean genomics and endangered species conservation, and lays the groundwork for future research on the speciation, ecology, and evolution of the ornate spiny lobster.

Sensing Pre- and Post-Ecdysis of Tropical Rock Lobsters, Panulirus ornatus, Using a Low-Cost Novel Spectral Camera

Tropical rock lobsters (Panulirus ornatus) are a highly cannibalistic species with intermoult animals predominantly attacking animals during ecdysis (moulting). Rapid, positive characterisation of pre-ecdysis lobsters may open a pathway to disrupt cannibalism. Ecdysial suture line development is considered for pre-ecdysis recognition with suture line definition compared for intermoult and pre-ecdysis lobsters emerged and immerged, using white, near ultraviolet (365 nm), near infrared (850 nm), and specialty SFH 4737 broadband IR LEDs against a reference of intermoult lobsters with no suture line development. Difficulties in acquiring suture line images prompted research into pre-ecdysis characterisation from the lobster’s dorsal carapace, due to its accessibility through a culture vessel’s surface. In this study, a novel low-cost spectral camera was developed by coordinating an IMX219 image sensor, an AS7265x spectral sensor, and four SFH 4737 broadband infrared LEDs through a single-board computer. Images and spectral data from the lobster’s dorsal carapace were acquired from intermoult, pre-ecdysis, and post-ecdysis lobsters. For the first time, suture line definition was found to be enhanced under 850 nm, 365 nm, and SFH 4737 LEDs for immerged lobsters, while the 850 nm LED achieved the best suture line definition of emerged lobsters. Although the spectral camera was unable to characterise pre-ecdysis, its development was validated when a least squares regression for binary classification decision boundary successfully separated 86.7% of post-ecdysis lobsters. Achieving post-ecdysis characterisation is the first time the dorsal carapace surface has been used to characterise a moult stage for palinurid lobsters.

Lessons from long-term monitoring of tropical rock lobsters to support fisheries management

Fishery-independent scientific surveys are highly valuable for monitoring lobsters and other fisheries. Yet, there are relatively few long-term monitoring surveys to support the provision of management advice. A number of challenges can prevent the continuity of long-term monitoring series. This paper uses the 35-year continuous annual dive surveys for Australia’s Torres Strait tropical rock lobster (TRL) to overview strengths and limitations of a long-term scientific survey, as well as lessons learnt from having overcome a range of challenges. Fishery-independent surveys are more reliable than fishery-dependent data and are more robust to external shocks such as market drivers and fuel prices. The primary purpose of the surveys is to provide a reliable index of stock abundance together with data to inform on size and age structure, plus model parameters and reference points. Here, we also highlight additional survey benefits including: yielding positive gains relative to cost, facilitating an adaptive management approach that serves as an early warning system, reducing and resolving inter-sector conflicts, reduced frequency of stock assessments, providing data from associated habitat monitoring, improved stakeholder buy-in, utility for development of Operating Models for Management Strategy Evaluation, contribution to achieving certification, contributing to biodiversity agreements and consistent cross-jurisdictional monitoring. We analyse lessons learnt from challenges such as changes in resource management, budget cuts, increased health and safety requirements, maintenance of capability and staff capacity, stakeholder buy-in, need to validate survey results, a pandemic and changing climate. Our experiences highlight why long-term scientific surveys are considered the gold standard for fisheries monitoring and we provide insights for building and maintaining key marine monitoring series.

Postprandial nutrient dynamics and their implications for formulated feed development for the ornate spiny lobster (Panulirus ornatus)

AbstractCrustacean feeding morphology and postprandial nutrient processing is a highly size‐selective procedure. The digestive system of lobsters is predicated on grinding feed to a fine particle size before digestion. Therefore, fine pregrinding of raw materials may bypass the need for extensive grinding in the proventriculus and expedite digestive and absorptive processes. Panulirus ornatus juveniles (N = 56) were allocated to four feed groups (n = 14). Groups A, B and C were fed nutritionally identical feeds featuring raw materials ground to 1000 µm (Feed A), 500 µm (Feed B) and 200 µm (Feed C) while the fourth group (Group S) acted as a 24‐h nonfeeding baseline control group. Sequential postprandial haemolymph extractions were performed at 0.5, 1, 1.5, 2, 3.5, 5.5 and 24 h across treatment groups. Haemolymph samples were assessed and analysed for brix (%), total proteins (g L–1), glucose (mmol L–1) and cholesterol (mmol L–1). Brix was found to have significant positive correlations with all the haemolymph biochemical properties while no significant correlations were identified between individual lobster size and haemolymph properties. Analysis of deviance applied to mixed effects models did not identify significant differences in haemolymph properties across feed groups. Trends identified here are indicative of diurnal rhythm patterns, likely orchestrated by the release of the crustacean hyperglycaemic hormone (CHH) when anticipating a meal. Additionally, the use of brix values, may not be optimal for identifying postprandial trends, yet could remain a valid indicator of longer‐term nutritional status.

Ontogeny of the Cytochrome P450 Superfamily in the Ornate Spiny Lobster (Panulirus ornatus).

Cytochrome P450s (CYP450s) are a versatile superfamily of enzymes known to undergo rapid evolution. They have important roles across growth and development pathways in crustaceans, although it is difficult to characterise orthologs between species due to their sequence diversity. Conserved CYP450s enzymes in crustaceans are those associated with ecdysteroidogenesis: synthesising and breaking down the active moult hormone, 20-hydroxyecdysone. The complex life cycle of the ornate spiny lobster, Panulirus ornatus, relies on moulting in order to grow and develop. Many of these diverse life stages have been analysed to establish a comprehensive transcriptomic database for this species. The transcripts putatively encoding for CYP450s were mapped using transcriptomic analysis and identified across growth and development stages. With the aid of phylogeny, 28 transcripts of 42 putative P. ornatus CYP450s were annotated, including the well conserved Halloween genes, which are involved in ecdysteroidogenesis. Expression patterns across the life stages determined that only a subset of the CYP450s can be detected in each life stage or tissue. Four Shed transcripts show overlapping expression between metamorphosis and adult tissues, suggesting pleotropic functions of the multiple Shed orthologs within P. ornatus.

The Effect of Supplementation of Fish Protein Hydrolysate to the BSF‐Based Aquafeed on the Growth, Survival, Fatty Acids, and Histopathology of Juvenile Lobster (Panulirus ornatus)

The present study aims to evaluate the effect of liquid fish protein hydrolysate (FPH) following fishmeal substitution with full‐fat and defatted BSF (black soldier fly, Hermetia illucens) meal in the feeds of juvenile ornate spiny lobster, Panulirus ornatus. The physiological aspects of juvenile lobsters including growth, fatty acids profile, and histopathology were observed. Six isoenergetic experimental feeds having a protein‐to‐energy ratio of 26 CP mg kJ−1 were formulated with the substitution of fishmeal at 25% using liquid FPH, full‐fat BSF (FBSF), defatted BSF (DBSF), and their combination. The specific growth rate, final body weight, final total length, and length increment of juvenile lobsters (initial weight was 0.21 ± 0.01 g and total length was 20.53 ± 0.12 mm) were significantly affected by the fishmeal substitution (P < 0.05) and improved with the addition of liquid FPH in the feeds containing FBSF and DBSF. The whole body proximate analysis showed that the liquid FPH to the feeds containing DBSF increased the ash and protein content significantly (P < 0.05). The total monounsaturated fatty acids (∑MUFA), saturated fatty acids (∑SFA), and omega 9 fatty acids (∑n−9 FA) of juvenile lobsters’ whole bodies fed with dietary DBSF and FPH supplementation were significantly higher than those of others (P < 0.05). The histopathological analysis indicated that the villus size and the muscle thickness in the intestine were not significantly affected by FPH supplementation. However, the hepatopancreas histopathology indicated the presence of B‐cells and R‐cells in the juvenile lobsters fed with FPH‐supplemented feeds. The present results suggested the supplementation of liquid FPH to the formulated feed with FBSF and DBSF for juvenile lobsters can improve the lobsters’ growth and fatty acids availability.

THE DEVELOPMENT OF LOBSTER PUERULUS (PANULIRUS ORNATUS AND P. HOMARUS) IN CAPTIVITY ENVIRONMENT

The present study was conducted to investigate the development of Panulirus ornatus and P. homarus puerulus larvae into juveniles in a captive environment. Pueruli were collected from the local fishermen and transported by air to the research facilities. Puerulus of each species were stocked into 3 floating plastic compartments (5 cm × 12 cm × 17 cm) with sufficient holes, aeration, and a filtration system until reached their first moulting. Results indicated that both puerulus species were completely moulted after 6 days of stocking with the survival rate of 100% and 93.3%. Moulting began on Day 5 for P. ornatus and Day 4 for P. homarus pueruli. The weight of P. ornatus increased significantly after the metamorphosis (P<0.05). The initial and final weights of P. ornatus were significantly greater than P. homarus (P<0.05). In addition, the total and carapace lengths of both species were significantly increased (P<0.05). Morphological observations indicated that there was a significant distinguishing feature such as the antenae form and body pattern colour of both species. In conclusion, proper handling of the pueruli according to each species is required to preserve the quality in order to achieve greater success in metamorphosis into juveniles.

Nitrogen excretion by the lobsters Panulirus ornatus and Thenus australiensis and uptake by the brown algae Sargassum siliquosum: Implications for integrated recirculated aquaculture systems

Farming extractive species such as macroalgae that take up nitrogen (N), with fed species (e.g., lobsters, finfish, prawns) is termed integrated multi-trophic aquaculture (IMTA). In recirculating aquaculture systems (RAS), high concentrations of nitrogenous waste can become toxic to the fed species and macroalgae offers a method of mitigating N waste. To utilise macroalgae as a biofilter for N waste, an understanding of their N ecophysiology of both the fed and extractive species is needed. In this study we first determine the ammonium and urea excretion rates for emerging aquaculture candidates the tropical rock lobsters, Panulirus ornatus (TRL) and slipper lobster, Thenus australiensis (SL). Using multiple flask uptake experiments, we then determined the N ecophysiology of the tropical brown macroalga, Sargassum siliquosum, to assess its potential use as a biofilter in a lobster RAS. Routine (basal) N excretion was predominantly ammonium with only a minor contribution of urea (8 and 13% for TRL and SL respectively). For both lobster species, ammonium and urea excretion substantially increased post-prandial, peaking at levels 3.6 times greater than basal amounts for TRL and 3.2 times greater for SL, and remained elevated for between 32 and 38 h. Uptake of both ammonium and nitrate by S. siliquosum showed saturating kinetics, where the kinetic parameter Vmax is the maximum rate of uptake, Ks is the half-saturation constant and the Vmax:Ks-ratio is a proxy for the algae's affinity of uptake for that respective nutrient: for ammonium Vmax = 110.9 μmoles g−1 dry weight (DW) h−1 and Ks = 37.9 μM and for nitrate Vmax = 152.7 μmoles g−1 DW h−1 and Ks = 58.52 μM. Urea uptake was highly variable with both positive and negative (i.e. urea release from tissue) rates recorded; when positive values were considered, Vmax = 55.5 μmoles g−1 DW h−1 and Ks = 17.65 μM. We used uptake and excretion rates from our study to derive a unit mass stocking ratio of algae to lobster (algae: animal) to offset N pollution in RAS. The ratios of TRL to algae to offset NH4+ and urea post-prandial were 5.15E-04 and 3.09E-04 respectively and for SL, 4.46E-04 and 6.31E-04 respectively. The findings serve as a reference for future studies on integrating Sargassum species into RAS and IMTA systems.

Sustainability level of the pearl lobster (Panulirus ornatus) aquaculture business using the systems of floating-net cage and fixed-net cage: A case study in South Sulawesi Province, Indonesia

Marine aquaculture is currently the fastest-growing seafood industry globally, offering a potential solution to overfishing problems, while enhancing food security and income generation. South Sulawesi, a province in Indonesia, is rich in aquaculture resources, one of which is lobster. The two commonly used aquaculture systems are the floating-net cage (KJA) and fixed-net cage (KJD). The growing market demand and rising lobster prices pose a threat to resource sustainability due to overexploitation. This is issue have to be addressed to achieve sustainable fishery development. Sustainability is the primary focus on global fishery development. According to the United Nations, sustainable development encompasses three dimensions: the economy, social and ecology. Therefore, sustainable fishery, particularly aquaculture, relies on obtaining significant benefits while minimizing environmental damage. Hence, this study aimed to analyze the sustainability level of the pearl lobster (Panulirus ornatus) aquaculture in South Sulawesi, based on the provided background information. The study included a sample of 62 farmers. The sample selection involved the use of the stratified sampling method, with 51 farmers from (KJA) and 11 farmers from (KJD). The sustainability analysis, conducted through assessment of based farmers’ perceptions, served as the analytical method. The findings revealed that pearl lobster (Panulirus ornatus) aquaculture has a medium level of sustainability. Employing Integrated Multi Tropic Aquaculture (IMTA) and Regional Integrated Multi Tropic Aquaculture (RIMTA) techniques is a recommended sustainability level.

Wooden traps can replace coral stone traps harvesting the wild lobster seed in mitigating the negative impact on the marine environment

Lobster seacage aquaculture has a significant social-economic contribution to many coastal communities throughout the central provinces of Vietnam. One of the issues of lobster aquaculture is that the industry entirely relies on the wild juvenile lobster (lobster seed) captured using traps made of coral stones, which affects the coastal ecology and environment. The present study was carried out to compare the catch efficiency of traps made of round timber poles (wooden trap) with conventional dead corals (coral stones) during the juvenile lobster fishing season in 2019 in the coastal area of Nha Trang city, Vietnam. Results showed that experimental wooden traps maintained the conventional catch rate level, with a significant proportion of Panulirus ornatus caught at larger carapace length than those caught by the coral stone traps. Our findings show the biological and environmental benefits of using alternative fishing methods would eliminate collecting coral stones to make lobster seed traps and contribute to coastal protection while maintaining the fishing operation and seed supplies for the lobster seacage farmers.

Tropical rock lobster (Panulirus ornatus) uses chemoreception via the antennular lateral flagellum to identify conspecific ecdysis

The tropical rock lobster, Panulirus ornatus, is a commercially important aquaculture species exhibiting complex social interactions in laboratory culture, including cannibalism of moulting conspecifics. Cannibalism of soft-shelled post-moult stage individuals is a major limitation during the juvenile stage of culture. Not limited to P. ornatus, cannibalism is widespread across farmed decapods, limiting stocking densities in crab, freshwater crayfish, and prawn species. To understand the mechanisms driving this behaviour and reduce its prevalence, we have investigated the role of chemoreception via the aesthetasc-bearing region of the lateral antennular flagellum, in the recognition of conspecific moulting cues. Differential expression analysis of several tissues in P. ornatus shows an upregulation of 70 ionotropic receptor isoforms, including co-receptors (IR25a and IR93a) and divergent receptors (IR4, IR7, and IR21a) in the aesthetasc-bearing region of the antennules. Deafferentation of the aesthetascs via deionised water exposure prevents juveniles from responding to conspecific moulting cues in a two-current choice flume, suggesting chemoreception, possibly olfaction, plays a role in identifying moulting juveniles. This is the first step in understanding the mechanisms via which cannibalism is triggered in juvenile P. ornatus culture. Further work in this area will help discover means to limit cannibalism in laboratory and commercial culture.

Cannibalism in cultured juvenile lobster Panulirus ornatus and contributing biological factors

Cannibalism is a major limitation to communally culturing the spiny lobster, Panulirus ornatus, and although frequently reported in research it is yet to be thoroughly investigated. To support continued innovation in culture, we must understand the contribution of cannibalism to juvenile mortality and identify influencing factors. This was accomplished through 900 h of time-lapse photography of three populations of juvenile lobsters over 30 d, including all ecdysis and cannibalism events to inspect individual weight, tank biomass, moult-stage, sex, and injury, as possible contributing factors. Total mortality was over 50% and attributed to the attack and cannibalism of moulting lobsters. Between 20 and 25% of moulting events in P. ornatus resulted in cannibalism of the moulting lobster. Population control and biomass stabilisation appear to be consequences of cannibalism, determined by fluctuations in tank biomass. Additionally, the moult stage of killer cannibals may suggest a nutritional benefit for lobsters in the latter half of the moult cycle. An increase in the average locomotor activity within a population during the hour before cannibalism occurs indicates that the factors driving cannibalism are present up to an hour before a moult. Here we demonstrate the flaws of previous assumptions related to the type and frequency of cannibalism in cultured P. ornatus systems and highlight contributing factors which warrant further study. Building from this research we may identify drivers of cannibalism among juvenile P. ornatus, with the aim of mitigating this behaviour in research and industry culture.

Species Composition, Relative Abundance, Distribution, and Size Structure of Spiny Lobsters (Panulirus spp.) in Eastern Visayas, Philippines

Spiny lobsters are an important resource of the artisanal fishery in Eastern Visayas, Philippines. It has long been harvested and contributes to the region's local economy. Despite being a high-value species, the spiny lobster resource has not been monitored and regulated for decades. This study aimed to assess the spiny lobsters in Eastern Visayas and provide recent information to support local resource management. Spiny lobsters were assessed from 2018 to 2019 in four major sampling areas in Eastern Visayas: (1) Guiuan and (2) San Policarpo in Eastern Samar province, (3) San Jose in Northern Samar, and (4) Silago-Hinunangan in Southern Leyte. Species composition, relative abundance, geographical and seasonality distribution, and size structure of spiny lobster resource in the region were described. Six species and subspecies of the genus Panulirus were observed in the catch landings: P. penicillatus (65%), P. ornatus (18%), P. versicolor (2.8%), P. femoristriga (5.3%), P. longipes longipes (6.1%), and P. longipes bispinosus (1.7%). Incidental catches (1.3%) of the ambiguous forms of P. longipes were also observed. P. penicillatus were more prevalent in areas exposed to the Pacific, such as Guiuan and San Policarpo, while adult P. ornatus were chiefly harvested in Northern Samar and Southern Leyte. The other lobster species were either occasional or rare in some areas. Calmer waters and good weather during dry months in Eastern Visayas allow fishers to sail and gather lobsters. The surge in the abundance of P. ornatus and P. penicillatus from July to December was also affected by market demand. Panulirus femoristriga, P. versicolor, and P. longipes subspecies generally peaked from April to June in Eastern Samar and July to September in Northern Samar and Southern Leyte areas. These species would decline in abundance towards the end of the year. The general size structure of spiny lobster catches in Eastern Visayas revealed extreme harvesting of juveniles and sub-adults (< 77.5 mm CL), except for P. ornatus. The fishery could be on the verge of growth overfishing since 50-90% of the catch have CL below their size at first maturity. Panulirus ornatus is targeted at larger sizes (96–107 mm CL) and as a live catch due to its high value and marketability. Raising awareness of the species, reinforcing existing regulations on minimum size limits, and prohibiting the use of compressor diving as a hazardous collection method should be prioritized by fishery managers to protect both the spiny lobster resource and the gatherers in Eastern Visayas.

Efficacy of isobutanol to reduce transport stress of juvenile ornate tropical rock lobster (TRL; Panulirus ornatus)

The ornate tropical rock lobster (TRL; Panulirus ornatus) is a fast growing spiny lobster that is prized for its vivid colouration and excellent eating qualities. The TRL aquaculture industry is reliant on the successful transport of juveniles to often distant grow-out sites from where they are harvested in the wild or raised in hatcheries. There has been mixed success transporting TRL juveniles, with high mortality rates which are typically associated with metabolic stress. Isobutanol, a food safe alcohol, has been shown to act as a sedative in adult TRL, as well as several other commercially important lobster species. This study found that juvenile TRL were rapidly sedated with isobutanol treatments at 350 and 500 ppm (15.05 and 6.47 min, respectively) and sustained inactivity was observed (36.12 and 60.62 min, respectively). Pre-treatment with isobutanol at 25 and 50 ppm led to decreased CO2 production rates during a 2 h air exposure experiment compared to untreated individuals (∼55 and 28%, respectively). Glycogen stores were maintained (∼75 higher) while lactate and ammonia concentrations were lower (∼50% and 40%, respectively) compared to untreated individuals. Isobutanol treatments at 25 and 50 ppm prior to 20 h of simulated transport improved overall survival (87.5% without treatment; 100% at either isobutanol treatment), while maintaining glycogen stores (∼80% higher) and limiting the accumulation of lactate and ammonia (∼25% and ∼ 45% lower, respectively) compared with untreated individuals. The results indicate that isobutanol treatment prior to air exposure during transport has the potential to improve outcomes from the transport of live juvenile TRL by decreasing overall metabolic stress and increasing survival.

The effect of defatted black soldier fly meal (Hermetia illucens) inclusion in the formulated diet on the growth, gene expression, and histopathology of juvenile lobster (Panulirus ornatus Fabricius, 1798)

The present study investigated the potential use of defatted black soldier fly (Hermetia illucens) meal as a protein source in the formulated feed for juvenile lobsters, Panulirus ornatus. A total of 160 heads of juvenile lobsters with initial weight of 0.24 ± 0.01 g and initial length of 21.77 ± 0.32 mm were distributed evenly into 16 rectangular fiberglass aquaria and kept individually for 8 weeks of the feeding experiment. Four formulated feeds containing defatted BSF meal as fishmeal replacements at 0%, 25%, 35%, and 50% and total dietary protein to energy ratio of ~ 26 g CP MJ−1 were prepared and assigned as BSF0, BSF25, BSF35, and BSF50, respectively. Fishmeal is technically a suitable aquafeed ingredient in terms of crude protein, moisture, and amino acid compositions. The partially substituted defatted BSF meal has higher crude lipid and ash content than fishmeal. At the end of week 8 of feeding trial, the specific growth rate, length increment, survival rate, and moulting rate of juvenile lobster were not significantly (P > 0.05) affected by the fishmeal replacement. The fishmeal replacement with the defatted BSF meal did not significantly (P > 0.05) alter the whole-body proximate composition of the juvenile lobster. However, it significantly (P < 0.05) affected the superoxidase dismutase of juvenile lobsters. The cytokine cell expression analysis indicated that up to 35% of fishmeal replacement increased the inflammatory cytokine cells (Interleukin 8 and 17) of juvenile lobster, while an adverse impact was observed on juvenile lobster receiving 50% of fishmeal replacement by BSF meal. Histopathological analysis showed that the hepatopancreas cells of juvenile lobsters were damaged following fishmeal replacement beyond 35%. The present study indicated that up to 35% of defatted BSF meal can be used as fishmeal replacement in the formulated feed of juvenile lobster.

Examining the inorganic elemental composition of lobster phyllosoma (Panulirus ornatus) with X-ray fluorescence microscopy.

The ornate spiny rock lobster, Panulirus ornatus, is an attractive candidate for aquaculture. The larval stages of spiny lobsters, known as phyllosoma, are complex with many developmental stages. Very little is known about the inorganic element composition of phyllosoma. In this study, a novel method using synchrotron X-ray fluorescence microscopy (XFM) was applied to investigate the distributions of metals potassium (K), calcium (Ca), copper (Cu), zinc (Zn), the metalloid arsenic (As), and nonmetal bromine (Br) within individual phyllosoma at stages 3, 4, and 8 of their development. For the first time, 1µm resolution synchrotron XFM images of whole phyllosoma as well as closer examinations of their eyes, mouths, setae, and tails were obtained. Elements accumulated in certain locations within phyllosoma, providing insight into their likely biological role for these organisms. This information may be useful for the application of dietary supplementation in the future to closed larval cycle lobster aquaculture operations.