Добірка наукової літератури з теми "Southern rock lobster"

Most lobster fisheries are characterized by high exploitation rates. This has led to substantial declines in the size structures of the populations over time as larger lobsters have been removed. Although both scientists and fishers have suggested that size related hierarchies could impact on lobsters entering traps, the effect of the size change on the selectivity of lobster traps as a population's size structure changes has not been investigated. This paper demonstrates that larger lobsters affect the entrapment of smaller lobsters and that this behaviour affects the selectivity of lobster traps. Both spatial and temporal (within season) factors were found to affect the selectivity plots. Spatial differences in selectivity were attributed to the broader size range of larger lobsters found in regions of faster growth. Temporal differences were attributed to the decline in larger lobsters over the course of a season caused by exploitation. There are also differences in trap selectivity between the sexes.

AbstractThe Western Kangaroo Island Marine Park (WKIMP) was declared as part of South Australia's representative system of Marine Protected Areas in 2009. Sanctuary Zone 3 (SZ-3) of the WKIMP is a no-take area protected from fishing since 1 October 2014 and is located within the Northern Zone Rock Lobster Fishery (NZRLF). In February 2017, a dedicated survey was undertaken to estimate the relative abundance (catch per unit effort (CPUE), kg/potlift) and size of southern rock lobster (Jasus edwardsii) inside and outside SZ-3. Survey results were then compared with historical estimates of abundance and size obtained from commercial fishery-dependent data. Survey estimates of relative abundance of legal-size lobsters were 4.4 times greater inside SZ-3 compared with outside in 2017. Since 2014, when fishing was last permitted inside SZ-3, the relative abundance of lobsters increased by 75%. The mean size of legal-size female and male lobsters also increased by 4.1% and 12.5%, respectively. The population responses recorded are consistent with the results recorded for southern rock lobster stocks in marine parks in other jurisdictions.

Paralytic shellfish toxins (PST) are found in the hepatopancreas of Southern Rock Lobster Jasus edwardsii from the east coast of Tasmania in association with blooms of the toxic dinoflagellate Alexandrium catenella. Tasmania’s rock lobster fishery is one of the state’s most important wild capture fisheries, supporting a significant commercial industry (AUD 97M) and recreational fishing sector. A comprehensive 8 years of field data collected across multiple sites has allowed continued improvements to the risk management program protecting public health and market access for the Tasmanian lobster fishery. High variability was seen in toxin levels between individuals, sites, months, and years. The highest risk sites were those on the central east coast, with July to January identified as the most at-risk months. Relatively high uptake rates were observed (exponential rate of 2% per day), similar to filter-feeding mussels, and meant that lobster accumulated toxins quickly. Similarly, lobsters were relatively fast detoxifiers, losing up to 3% PST per day, following bloom demise. Mussel sentinel lines were effective in indicating a risk of elevated PST in lobster hepatopancreas, with annual baseline monitoring costing approximately 0.06% of the industry value. In addition, it was determined that if the mean hepatopancreas PST levels in five individual lobsters from a site were <0.22 mg STX equiv. kg−1, there is a 97.5% probability that any lobster from that site would be below the bivalve maximum level of 0.8 mg STX equiv. kg−1. The combination of using a sentinel species to identify risk areas and sampling five individual lobsters at a particular site, provides a cost-effective strategy for managing PST risk in the Tasmanian commercial lobster fishery.

ABSTRAK Lobster (Panulirus spp.) adalah komoditas perikanan penting dan ekonomis tinggi. Spesies yang paling sering dan dominan tertangkap adalah lobster batu. Meningkatnya permintaan lobster menjadikan nelayan melakukan kegiatan penangkapan secara terus menerus. Penelitian ini bertujuan untuk menganalisis hubungan panjang-berat dan rasio jenis kelamin (sex ratio) lobster batu (Panulirus penicillatus). Penelitian dilakukan pada Februari 2017 sampai dengan Agustus 2017 di pantai selatan Yogyakarta. Kajian stok lobster dilakukan melalui survei yang meliputi metode deskriptif, observasi dan wawancara. Pemilihan lokasi pengambilan sampel dilakukan secara terpilih (purposive) yaitu pantai Ngrenehan, Baron, Drini dan Tepus. Total sampel lobster batu yang diperoleh sepanjang penelitian sejumlah 546 ekor, yang terdiri dari lobster jantan 289 ekor (53%) dan lobster betina 257 ekor (47%). Hasil penelitian menyatakan bahwa pola hubungan panjang dan berat lobster batu memiliki sifat allometrik negative dengan persamaan W= 0,004 L 2,577 pada lobster jantan dan W = 0,007 CL 2,481 pada lobster betina. Perbandingan nisbah kelamin lobster batu jantan dan betina adalah 1,12 : 1. ABSTRACTLobster (Panulirus spp.) is an important and economically high fishery commodity. The most frequent and dominant species caught is rock lobster. The increasing demand for lobsters makes fishermen conduct continuous catching activities. The study aims to analyze the relationship of length-weight and sex ratio of rock lobster (Panulirus penicillatus). The research was conducted from February 2017 to August 2017 in southern coast of Yogyakarta. The study of lobster stocks was conducted through surveys that included descriptive methods, observations and interviews. The sampling location was chosen purposively, namely Ngrenehan, Baron, Drini and Tepus. Total samples obtained throughout the study amounted to 546 double-spined rock lobster, consisting of 289 males (53%) and 257 females (47%). The results stated that the length and weight relationship pattern of rock lobsters is negative allometric, with the equation W= 0,004 L 2,577in males lobster and W = 0,007 CL 2,481 in females lobster. The sex ratio double-spined rock lobster between males and females lobster is 1,12 : 1.

Abstract Green, B. S., and Gardner, C. 2009. Surviving a sea-change: survival of southern rock lobster (Jasus edwardsii) translocated to a site of fast growth. – ICES Journal of Marine Science, 66: 656–664. In an experiment aimed at increasing the yield and value of the fishery for southern rock lobster (Jasus edwardsii), 1998 pale and slow-growing lobsters were translocated to sites where lobsters grow faster naturally and develop higher value market traits. Survival of lobsters in their new habitat was critical to the viability of this experiment. To estimate survival, the release site was surveyed every 1–3 months for 2 years. Apparent survival of translocated lobsters was compared with survival of resident lobsters tagged in a similar period using Cormack–Jolly–Seber modelling on mark–recapture data. Lobster survival was not influenced by size, gender, or origin (translocated or resident) alone. The four most parsimonious models suggested slightly lower apparent survival in translocated lobsters immediately after release compared with all other lobsters, but support for these models was weak (∑QAICc weights 62%). The differences in apparent survival were not likely to be significant because of large variance when averaged over all the models. Apparent survival of newly released translocated lobsters was 92% (72–98, 95% CI) compared with 97% (95–98, 95% CI) for all other lobsters. Potential sources of differences in survival are movement from the release site or greater predation on pale lobsters. Losses of lobster through release mortality were low and unlikely to influence the feasibility of translocation as a tool to enhance the value of the fishery, although it would be prudent to include 5% mortality of translocated lobsters in future models of translocation feasibility.

AbstractWe demonstrate the use of molecular techniques to detect specific prey consumed by the southern rock lobster (Jasus edwardsii). A quick and non-lethal method was used to collect rock lobster faecal material and a molecular protocol was employed to isolate prey DNA from faecal samples. The isolated DNA was amplified using the polymerase chain reaction (PCR) with PCR primers designed to target specific prey items. Feeding experiments determined that DNA from black-lipped abalone (Haliotis rubra) and sea urchins (Centrostephanus rodgersii and Heliocidaris erythrogramma) can be detected in rock lobster faecal samples within seven hours and remains present for up to 60 h after ingestion.

For most of the year, the size-frequency distribution of trap-caught southern rock lobster, Jasus edwardsii, reflected size-specific catchability rather than the size-frequency distribution of the population in a scientific reserve in Tasmania, Australia. The size-frequency distributions of the population on the ground and of lobsters captured in traps were similar only during a few months, typically during moulting and mating. Small males and females were usually under-represented in traps. Catchability generally increased with size, but varied with sex and season. During moulting and mating, size-specific catchability and relative selectivity of larger animals were similar to or lower than for smaller animals. The relative pattern of catchability throughout the year was similar for most size classes within each sex. Negative associations between small and large lobsters in traps were stronger in winter than in summer, indicating strong behavioural interactions. These interactions could explain the lower catchability of smaller lobsters. Relative selectivity estimates using tag–recapture and size-specific catchability data provided generally similar results.

Abstract Background Paralytic shellfish toxins (PST) are a significant problem for the Tasmanian shellfish and Southern Rock Lobster (Jasus edwardsii) industries, and the introduction of a rapid screening test in the monitoring program could save time and money. Objective The aim was to perform a single-laboratory validation of the Neogen rapid test for PST in the hepatopancreas of Southern Rock Lobster. Methods The AOAC INTERNATIONAL guidelines for the validation of qualitative binary chemistry methods were followed. Three different PST profiles (mixtures) were used, of which two were commonly found in naturally contaminated lobster hepatopancreas (high in gonyautoxin 2&3 and saxitoxin), and the third toxin profile was observed in a few select animals (high in gonyautoxin 1&4). Results The Neogen test consistently returned negative results for non-target toxins (selectivity). The probability of detection (POD) of PST in the lobster hepatopancreas using the Neogen test increased with increasing PST concentrations. POD values of 1.0 were obtained at ≥0.57 mg STX-diHCl eq/kg in mixtures 1 and 2, and 0.95 and 1.0 for mixture 3 at 0.79 and 1.21 mg STX-diHCl eq/kg, respectively, with a fitted POD of 0.98 for 0.80 mg STX-diHCl eq/kg. The performance of the Neogen test when using four different production lots (ruggedness) showed no significant differences. Conclusions The results of the validation study were satisfactory and the Neogen test is being trialed within the Tasmanian PST monitoring program of Southern Rock Lobster. Highlights The Neogen rapid kit was successfully validated for the detection of PST in Southern Rock Lobster hepatopancreas.

The annual commercial catch from the Southern Zone of the South Australian rock lobster (Jasus edwardsii) fishery is ~1900 tonnes, representing ~50% of total landings from south-east Australia. A single minimum legal size (MLS) of 98.5 mm carapace length (CL) exists across the entire zone. Fecundity (F), size at onset of maturity (SOM) and relative reproductive potential (RRP) of female rock lobsters were investigated in two major fishing regions, i.e. the North Southern Zone (NSZ) and South Southern Zone (SSZ) with a view to providing a basis for future fine-scale spatial management of the resource. F ranged from 45,292 to 466,800 eggs per female and increased proportionally with CL according to the relationship: F = 0.0584 × CL3.1642. F was significantly higher in the NSZ compared to the SSZ but was attributed to differences in lobster size between regions. There was no significant difference in the number of eggs · g−1 of egg mass between areas. SOM, estimated as the size at which 50% of females reached sexual maturity (L50) was higher in the NSZ (104.1 mm CL) compared to SSZ (92.3 mm CL). Approximately 20% of lobsters above the MLS in the commercial catch in the NSZ were under the L50 estimate. RRP, as a measure of egg production, was calculated for each size-class from the product of F, SOM and population length–frequency. The modal RRP size-classes in the NSZ were 117.5–122.5 mm CL, while in the SSZ it was 97.5–102.5 mm CL. Only 6% of RRP was contributed by female rock lobsters below the MLS in the NSZ, compared to 34% in the SSZ. Regional differences in SOM and RRP in the Southern Zone of South Australia suggest that different MLSs may be beneficial, particularly if the fishery is to be effectively managed at finer spatial scales.

Larasati RF, Suadi, Setyobudi E. 2018. Short Communication: Population dynamics of double-spined rock lobster (Panulirus penicillatus Olivier, 1791) in Southern Coast of Yogyakarta. Biodiversitas 19: 337-342. The southern coast of Yogyakarta, Indonesia, near to the Indian Ocean borders is a preferable habitat for lobster. Double-spined rock lobster (Panulirus penicillatus) is one of the prevalent species caught by fishermen. However the increased number of capture activities had an effect on the sustainability of global lobster fisheries. In order to sustain these fisheries resource, the preservation management of lobster should include wild stock assessments. Currently, the effect of fishing pressures on populations of P. penicillatus is limited. The objective of this research was to identify several factors affecting lobster population in terms of growth (carapace length (CL) and mass), recruitment, mortality rates, and exploitation rates in this species. Results showed that double-spined rock lobster had a longer size (CL) (45.2-55.1 mm) than that of females (55.2 mm-65.1 mm). While the growth rate (K) of males lobster is 0.85 year-¹ and its CL reached an asymptotic point at 125 mm (12 years old). Growth rate of females double-spined rock lobster was 0.55 year-¹ and its CL reached an asymptotic point at 125.5 mm (15 years old). The total estimation of mortality rates of double-spined rock lobster was 2.46, wherein 2.56 year-¹ for males and females, respectively. The estimated values of M were 1.08, 0.81 year-¹ for males and females, respectively while the respective values of F were 1.38 year-¹ and 1.75 year-¹ for males and females. The exploitation rate of males was 0.56 and females was 0.68. It has exceeded the optimal level (0.5) and reached overfishing value. Based on these results, it suggest that the time management of fishing activities such as by several approaches including the restricted time of fishing activity in spawning and recruitment season, the management of catching effort by the development of environment-friendly fishing gear, and the development of the lobster hatchery to reproduce and maintain their population naturally.

The southern and western rock lobsters (Jasus edwardsii and Panulirus cygnus, respectively) form the basis of two of the major seafood export industries in Australia; between them earning over $500 M export dollars yearly. Although a major portion of the catch is exported as 'whole-cooked' or 'tailed' products, an increasing share of the catch is exported live. The majority of lobsters arrive at the processing sheds as live lobsters. However, a lack of basic physiological information has impeded advances in the design and management of transport and holding systems, often resulting in a deterioration of the physiological condition of some lobsters. Such physiological deterioration may result in the final product choice for the processors being limited, leading to a reduced value of the catch. The aim of this study was to develop an understanding of the physiology of lobsters, especially in relation to factors the lobsters may be subjected to during post-capture handling practices. This information could be used to redefine postcapture handling practices and holding system design and management. Standard oxygen consumption of both species increased in response to increases in temperature and body weight. Activity had the greatest effect on oxygen consumption rates, causing an approximate 3-fold increase above standard rates. The increase in oxygen consumption due to activity decreased at temperatures approaching the upper and lower extremes of each species. After a period of activity and emersion oxygen consumption remained elevated for up to 8 hours. A marked diurnal rhythm was evident, with a 48% and 87% (J. edwardsii and P. cygnus, respectively) increase in oxygen consumption at night. This was largely related to increased activity at night. Feeding resulted in a substantial (greater than 2-fold in P. cygnus) and sustained (up to 48 hours) increase in oxygen consumption. Both species were essentially oxygen regulators, able to maintain standard rates of oxygen consumption down to around 30% water oxygen saturation. Below that oxygen level the lobsters became oxygen conformers. Activity resulted in an approximate doubling of the water oxygen level at which lobsters acted as oxygen conformers. The total ammonia nitrogen (TAN) excretion rates of both species increased with increases in temperature and body weight. Activity had minor influence on the TAN excretion rate. A diurnal rhythm was evident in J. edwardsii but not in P. cygnus. Feeding had a large affect on the TAN excretion rate, with an approximate 6-fold increase occurring in each species. The excretion rates remained high for over 24 hours post-prandial. The effect of the dissolved oxygen level on recovery of P. cygnus from a period of activity/emersion was investigated. Based on the rate of recovery of various physiological parameters (oxygen consumption, haemolymph ammonia, lactate, glucose, and pH), the maintenance of water oxygen levels close to 100% saturation is recommended. Water oxygen levels less than 60% saturation slowed the rate of recovery. All lobsters recovering in water with oxygen levels less than 20% saturation died. Carrying P. cygnus out of water imposes physiological disturbances to the lobsters. The severity of the disturbances increased when the relative humidity was lower and when wind was present. Spraying water over the lobsters prevents some of the physiological consequences of emersion, such as decreases in pH and haemolymph ammonia buildup, however it does not prevent haemolymph lactate increases. Therefore, lobsters still rely on anaerobic metabolism when emersed in sprays. There was no evidence that failure of lobsters to recover from a period of emersion was caused by gill damage. A half hour period of emersion/handling at 23°C caused large physiological disturbances of P. cygnus. Halving the emersion/handling time did not decrease the extent of the physiological disturbances. Slow-chilling the lobsters to 11°C prior to emersion/handling, was an effective means of decreasing the physiological disturbances associated with emersion. This study has developed our understanding of the physiological responses of the southern and western rock lobsters to factors affecting them during postcapture processes, and will allow the design and management of rock lobster holding facilities to be based on a sound scientific basis. It also represents a major contribution to knowledge on respiration and nitrogen metabolism of large decapod crustaceans.

Catchability is estimated indirectly as a 'nuisance' variable in the spatially explicit stock assessment model of the southern rock lobsters Jasus edwardsii in Tasmania, Australia. This study attempted to identify the key mechanisms influencing catchability to enable direct independent estimates of monthly catchability. Seasonal variation in catchability of the southern rock lobster Jasus edwardsii was estimated in a scientific reserve in southeast Tasmania by comparing estimates of lobster density based on direct visual observations underwater with concomitant estimates from trapping surveys. Underwater density estimates of undersized and legal-sized male and female lobsters greater than 80 mm carapace length did not change significantly over the 14 month study period with the exception of undersized males (smaller than 110 mm carapace length). Sex ratios remained constant at approximately 1:1. In marked contrast, catch rates of males and females and the sex ratio of trapped lobsters varied strongly with season, implying that catchability varies seasonally and with sex. Impact of capture on subsequent catchability appeared to be weak, since the ratios of tagged animals in the population observed underwater generally reflected recapture rates of tagged animals in trap catches. Size-specific catchability generally increased with size, but also varied with sex and season. During moulting and mating, size-specific catchability and relative selectivity did not increase, and sometimes decreased for larger animals. The size-frequency distributions of lobsters captured in traps therefore rarely reflected the size-frequency distribution of the population on the ground. Negative associations between small and large lobsters in traps were stronger in winter than in summer, indicating strong behavioural interactions. These interactions can account for the lower catchability of smaller lobsters. Relative selectivity estimates using tag-recapture and size-specific catchability data provided similar results. Seasonal variation in catchability of legal-sized males and females in the scientific reserve was described by modelling the effects of water temperature, moulting and mating. Seasonal changes in water temperature described 63% of the variation of catchability for males, but were a poor predictor of catchability for females outside winter. Both moulting and mating were highly synchronised, although males and females moulted at different times of the year. Gaussian probability density functions were used to represent the timing and intensity of moulting, mating and subsequent compensation periods, and were added to the description of seasonal temperature changes. Four Gaussian functions based on independent biological data considerably improved the model fits for the catchability of males (R2 = 0.83). However, adding a single Gaussian function to the temperature model, representing a combined moulting and mating period based on independent biological data, provided a less adequate description of the variation in catchability of females (R2 = 0.49). Only models unconstrained by the observed timing of these events provided a good fit (R 2 = 0.74). The seasonal catchability models developed for the reserve population were applied to catchability over several years in two commercially fished regions of Tasmania. Catchability was estimated using commercial catch and effort data and fishery-independent estimates of exploitation rates. The seasonal catchability models suggest that similar environmental and physiological processes were the main factors determining seasonal catchability in the two fishery regions, but these factors varied considerably in their relative importance between the two regions. Interannual variation in relative catchability was correlated with density-dependent processes. Full models described 72% of the overall variation in catchability over 6 years in the south and 80% of the variation over 4 years in the north. More work is required before direct estimates of catchability can be included in stock assessment models. In particular, region-specific patterns of seasonal catchability, and the relationship between density-dependent processes and the interarmual variation in catchability need to be determined, before catchability can be reliably predicted in future years and in other regions of Tasmania. Nevertheless, this work has greatly improved our understanding of the processes that apparently underpin seasonal catchability.

The aim of this project was to define more clearly the culture conditions for the propagation of the southern rock lobster (Jasus echvardsii) in relation to environmental bioenergetic constraints. The effects of temperature and photoperiod on the first three stages of development were first studied in small-scale culture experiments. Larvae reared at 18°C developed faster and reached a larger size at stage IV than larvae cultured at 14°C. Development through stage II was shorter under continuous light. However, the pattern of response to photoperiod shifted at stage III when growth was highest in all the light/dark phase treatments than under continuous light. The influence of temperature and light intensity in early-stage larvae was further investigated through behavioural and physiological studies. Results obtained in stages I, II and III larvae indicated an energetic imbalance at high temperature (~22°C). The behavioural response of stage I larvae to light intensity suggested that light may be used to control behaviour in culture conditions. Early-stage larvae showed higher oxygen consumption, nitrogen excretion, and feed intake under light than in the dark. This may be due to the demonstrated increased activity under light conditions. A technique based on the chemical immobilisation of larvae was developed to assess the effect of temperature on the standard metabolic rate and the energetic cost of swimming in phyllosomas. Estimates of larval locomotor activity at different temperatures obtained through measurements of oxygen consumption were in agreement with behavioural response under the same conditions. The water quality requirements off. edwardsii larvae were determined for dissolved oxygen, salinity, and ammonia. A critical oxygen tension of `4.3` `ml` `O_2` `1^-1` was found for stage I larvae at 18°C. Stage I larvae were found to be stenohaline and a 3 ppt departure from normal salinity (34 ppt) during culture had a significant effect on growth. The cost of osmoregulation was examined in newly-hatched larvae and in stage I phyllosomas acclimated or not to sub-normal salinities. Safe levels of total ammonia concentration determined for stages I, II, III, and IV were `2.65` `mg` `1^-1`, `3.83` `mg` `1^-1`, `4.37` `mg` `1^-1`, and `2.98` `mg` `1^-1`, respectively. The results documented throughout this thesis highlighted the significance of environmental manipulation to achieve greater survival and growth during the larval development of J. edwardsii. In addition, information on the environmental physiology and behaviour of early-stage larvae provided an insight into an integrated approach, which at term will allow for the definition of system and dietary requirements of all developmental stages.

Understanding the mechanisms driving larval dispersal and connectivity is of ecological relevance and is beneficial in fisheries management. Defining population structure and stock boundaries helps in management of spawning stock biomass and annual harvests. Moreover, determining if there are patterns in dispersal can help identifying source populations that need management strategies directed towards maintaining appropriate levels of egg production. The Southern rock lobster, Jasus edwardsii, extends around southeast Australia and New Zealand and supports valuable fisheries in both countries. Adults J. edwardsii do not migrate and their phyllosoma larvae, the dispersal stage, are adapted for drifting for approximately 12 to 24 months of pelagic larval duration. Consequently there has been an assumption of genetic homogeneity within the population throughout Australia. The assumption of panmixia has been supported by larval transport simulations and previous studies on genetic connectivity. The general eastward flow of currents in southeast Australia has been identified as the likely main dispersal mechanism. South Australia is a highly productive area, and is predicted by oceanographic models to be a source of larvae to the Tasmanian fishery. A second prediction from larval transport simulations is that regional self-recruitment varies markedly across the species range in Australia. Long-term monitoring of recruitment throughout the fishery shows high year-to-year variability in recruitment, as well as regional fluctuations. This has been linked to changes in environmental conditions. Fluctuations in recruitment magnitude can reduce the accuracy of population modeling of the stock, which is used to determine harvest strategies. In this thesis I assessed variability in genetic identity of Southern rock lobster at different spatio-temporal scales to evaluate drivers of population structure. I reviewed possible biological, environmental (e.g., dispersal history) or adaptive drivers (e.g., natural selection) by analyzing single nucleotide polymorphisms (SNPs) markers generated using double digest restriction site-associated DNA sequencing (ddRADseq). I measured genetic variability in J. edwardsii across three spatial scales, broad (1,000’s km), medium (100’s km) and fine-scale (10’s km), as well as two temporal scales, within a year and between years. In chapter 2, large-scale connectivity and potential for local adaptation between adult J. edwardsii from Australia and New Zealand was investigated using neutral and outlier markers. There was large-scale genetic divergence between Australia and New Zealand, two countries thousands of kilometres apart, at neutral regions of the genome (F\(_{ST}\) = 0.022), supporting previous findings of limited larval dispersal across the Tasman Sea. A much larger genetic differentiation was detected (F\(_{ST}\) = 0.134), using regions of the genome under putative selection suggesting local adaptation and post-settlement mortality of unfit genotypes. In chapter 3 I assessed the extent and patterns of genetic variability in new recruits through time on a medium spatial scale. To determine the role of genetics in the observed interannual variability and how post-settlement selection acts to modify the observed structure in recruits, pueruli and post-pueruli settling during four consecutive years were analyzed. Interannual genetic variability of recruits within and between two sites located 100’s of kilometres apart in South Australia and Tasmania provided support for chaotic genetic patchiness. Lower genetic diversity was observed during years of low puerulus catch rates at the Tasmanian site, suggesting regional genetic differences in recruitment. Additionally, the magnitude and strength of genetic divergence detected in the markers under putative positive selection also exhibited temporal and spatial variability. Both locations exhibited a single marker under putative positive selection in common across years, providing weak evidence for post-settlement selection. In chapter 4 I assessed fine-scale temporal and spatial genetic and phenotypic divergence in recruits across a latitudinal gradient. This was done using new recruits within one recruitment season in Tasmania from sites 10’s of kilometres apart. There was a lack of overall population structure identified between three sites along a latitudinal gradient, but genetic divergence at a small spatial scale suggested chaotic genetic patchiness. Individuals sampled from the southernmost site during three consecutive monthly collections were genetically divergent from each other. There were also phenotypic differences of pueruli between sites and months of settlement; individuals at the northernmost site were consistently smaller at settlement. Collective dispersal is a possible mechanism of larval J. edwardsii, based on significant phenotypic differences between sites that were persistent through time. This implied that larvae released during the same spawning event could maintain cohesiveness until settlement, leading to genetic patchiness among individuals recruiting during the same year. In chapter 5 I tested a number of the dispersal pathways projected by a larval transport simulation model for J. edwardsii. The predicted population of origin of pueruli caught in collectors in South Australia and Tasmania was then tested using genetic assignment to determine if they were the likely point of origin. All three adult lobster sampling sites were assigned as equally likely source for recruits in both South Australia and Tasmania. These results further evidenced the high level of genetic exchange in the Australian J. edwardsii population. In general, the findings of this thesis provide new evidence on the dispersal mechanisms used by larval J. edwardsii driving the observed genetic variation in recruits. The high level of genetic admixture found herein highlights the need of a coordinated fisheries management strategy between states in order to protect subpopulations that constitute important source of recruits.

Recent interest in the aquaculture of southern rock lobster Jasus edwardsii has developed with increasing demand for lobsters and declining wild fisheries. The potential economic success oflobster aquaculture will depend on the development of efficient formulated feeds specifically designed to meet the nutritional requirements of this species. Experimental lobster feeds are currently based on fish meal and fish oil formulations, and although good survival and growth up to that of lobsters fed fresh blue mussels has been achieved, the potential to increase growth through nutrient level manipulation has not been achieved to date. Investigations of appropriate experimental methods, and subsequent determination of ingredient digestibility, lipid utilisation, histological assessment of energy storage, lipid class and fatty acid composition and energy substrate for metabolism were performed through a series of experiments with juvenile J edwardsii. Apparent digestibility of protein and carbon from novel dietary ingredients was assessed to screen potential protein sources for dietary inclusion. The apparent digestibility of crude protein in mussel meal (98%), prawn meal (77%), and lupin flour (100%) were higher than the current standard fish meal (63%), and the defatting of fish meal decreased the apparent protein digestibility (53%). Squid (7%) and canola meal (38%) were poorly digested by lobster. The examination oflobster metabolism when fed varying protein levels was measured through oxygen consumption and ammonia-N excretion and their atomic ratio. Lipids were metabolized in feeds containing low protein levels, and carbohydrate and protein were metabolized in high protein feeds, and suggested that carbohydrates were not well utilised. Isonitrogenous and isolipidic diets were formulated to include a range of potential protein meals and lipid sources, to assess the effect of lipid composition and source on the growth and composition of juvenile lobsters. Fish oil was replaced with vegetable and alternate marine oils in formulated feeds with no significant reduction in weight gain (1.2 - 2.87 g), however lobsters fed the reference feed (fresh blue mussel, Mytilus edulis) gained more weight than those fed formulated feeds (5.65 g). Lipid class analysis of the digestive gland lipids indicated high levels of triglycerides (TAG) and diglycerides (DG) in the digestive gland oflobsters fed fresh mussels (FrM), mussel meal (MM) and fish oil with lecithin (FOL). High TAG and DG were associated with digestive gland lipid storage, and were correlated to high productive protein values (r=0.755, P=0.005, n=12). Lipid histology of the digestive gland confirmed lipid deposition as droplets in R-cells, and the presence of abundant reserve cells in the digestive gland of fast growing lobsters was observed. Dietary phospholipids produced the fastest growth rates in FrM and MM, while dietary triglycerides did not promote growth. Fatty acid composition of lobster digestive gland closely resembled the dietary lipid profile however the predominantly structural lipids in the whole body tissue, more strongly reflected the profiles of control lobsters. The addition of lecithin to fish oil improved the deposition of lipid droplets in the digestive gland. This study provides greater understanding of the interactions between dietary ingredients and their effects on protein and lipid metabolism, retention and growth and provides valuable information to develop formulated feeds for J. edwardsii.

The Tasmanian southern rock lobster (Jasus edwardsii) fishery has a single Tasmania-wide management system despite large spatial variations in the biology (growth) and market traits(shell colour, body shape and live transport condition). This has created uneven distribution of harvest rates around the State where red, fast-growing, shallow-water lobsters are heavily targeted by fishers due to their high market demand, while pale, slow-growing, deep-water rock lobsters have a much lower rate of exploitation. In an attempt to improve yield, marketability and value of deep-water southern rock lobsters, translocation of lobsters between regions was examined as a supplementary management strategy for the Tasmanian rock lobster fishery. Adult deep-water lobsters were moved inshore to shallow-water reefs where changes to growth, market traits and body condition were monitored through recapture surveys. Red pigmentation in shell colour decreased with depth across southern Australia. Most of the catch is sold into Asian live markets where there is a preference for red lobsters. This market preference has lead to the price discounting of lobsters, which was estimated at a total of AUS$6.67 million / year for the Tasmanian Rock Lobster Fishery. Morphological market traits of leg length and abdomen shape were also different between deep and shallow-water J. edwardsii populations and between the sexes in each population. Nutritional indicators of condition did not differ among adult deep-water, shallow-water and translocated male lobsters, however fatty acid profiles indicated dietary differences between deep and shallow-water lobsters. Haemolymph condition indices detected significant differences in the post-harvest condition between deep-water and shallowwater lobsters. Translocating small, pale adult lobsters into a shallow water habitat resulted in a number of changes important to the yield and value of the fishery. Growth rates of translocated adult lobsters increased at their first moult in their new habitat, exceeding that of resident deep-water lobsters from the original site. Growth of translocated females exceeded resident shallowwater females in the first year post-release. Translocation changed the pale colouration of deep-water lobsters into the bright red grade most sought after by the Asian market, however changes in morphology were only partial and may require several moults for a complete change in shape. Dietary fatty-acid profiles of translocated lobsters matched those of the resident lobsters, while significant levels of essential omega-3 fatty acids in the muscle tissue of translocated lobsters suggest enhanced nutritional condition after translocation. The post-harvest condition of resident shallow-water lobsters and translocated lobsters were similar when recaptured 12 months later. Translocation could be an effective management tool to add value to the less marketable deep-water southern rock lobsters. These results on the magnitude and timing of improvements in market traits will now contribute towards the economic and biological evaluation of the feasibility of translocation as a fisheries enhancement strategy for the Tasmanian Rock Lobster Fishery.

This study examined the life history of juvenile Jasus edwardsii, with a particular emphasis on ontogenetic shifts in ecology, and how these shifts and other ecological factors may influence recruitment rates to maturity and the fishery. The aspects examined included settlement, density and distribution, shelter utilisation and availability, diet, morphology, as well as growth, survival and movement. Shifts in ecology, particularly in dispersion pattems, shelter utilisation and diet were found throughout the juvenile size range. However, a distinct early benthic phase was recognised, with a rapid transition from this phase occurring at approximately 35 mm carapace length (CL). More gradual shifts in ecology occurred after this size. Early benthic phase lobsters were solitary dwellers, randomly to evenly dispersed over the reef and consumed predominantly ophiuroids, isopods and bivalves. In contrast, larger juveniles were gregarious, cohabiting in shelters with conspecifics and having clumped shelter distributions. They also consumed predominantly bivalves, crabs and urchins. These changes corresponded with allometric changes in morphology. Early benthic lobsters had specific shelter requirements compared to the broader range of shelters used by larger lobsters, and were more likely to be affected by limitations in shelter availability. Shelter availability was dependent on the substrate type and structure, but was not found to be limiting during this study. However, settlement rates during this study were low, and shelter may be limiting at higher settlement rates. Intemal microtagging techniques were developed to examine the population dynamics of newly settled lobsters (from 10 mm CL or 0.6 g). The growth of microtagged lobsters released in the wild was seasonal, ranging from a mean of 2.5 mm CL per month in summer to a mean of 1.1 mm CL per month in the winter. The loss rates of tagged lobsters from the study area, due to mortality and emigration, were high and varied between release batches, the probability of survival ranging from a maximum of 51% to less than 1%. Lobsters remaining in the study area had a high fidelity to particular shelters. The results of this study suggest that the early benthic phase is a critical phase in determining recruitment rates to maturity and the fishery, particularly due to the influences of specific shelter requirements, increased susceptibility to predation and variations in growth and survival.

The southern rock lobster (SRL), Jasus edwardsii (Hutton, 1875) (Crustacea: Decapoda: Palinuridae), is one of Australia and New Zealand’s most valuable fishery resources. A large scale and prolonged reduction in the recruitment of SRL during years 2000 – 2010 translated into significant stock declines across the Australian fisheries. The geographical range of SRL spans more than 5000 km from Western Australia to New South Wales along the southern coast of Australia including Tasmania and around the entire New Zealand. Connectivity between distant populations is achieved solely through larval dispersal with adult movement being limited (Booth, 1997; Linnane et al., 2015). The SRL has a pelagic larval duration (PLD) of up to 24 months, one of the longest known in the marine environment and the longest among all rock lobsters (Booth, 1994; Bradbury and Snelgrove, 2001). SRL larvae can be carried hundreds of kilometres offshore and away from their origin, potentially connecting spawning grounds and recruitment sites hundreds of kilometres apart. This potential for widespread dispersal combined with unpredictable inter-annual and spatial variability of egg production and recruitment, make biophysical modelling an ideal approach to examine population connectivity for this species. This thesis assesses the population connectivity of SRL throughout its geographical distribution by the means of a larval dispersal model built utilising the best available hydrodynamic models and evidence based species-specific biological parameters. Prior to setting up the larval dispersal model, I performed a validation of two hydrodynamic models available in the study area, by comparing the model predicted time series of seawater temperature and ocean currents to in situ mooring measurements (Chapter 2). I found that the accuracy of the hydrodynamic models varied with the parameter investigated, the depth of the measurement and the geographical region. The model predictions of water temperature were more accurate than the predictions of ocean current velocities. This study identified important inaccuracies in the hydrodynamic models’ estimations of ocean parameters and on time scales relevant to larval dispersal studies. The largest errors in global ocean models are seen in coastal regions, where models have poor coverage due to their lower spatial resolution. Many global ocean models also do not explicitly resolve key hydrodynamic features in the coastal regions. I investigated the effect of nesting a highly-resolved coastal hydrodynamic model – ETAS – within the global BRAN model, on the passive dispersal of larvae released on the east coast of Tasmania (Chapter 3). I found significant differences in larval trajectories and dispersal metrics between the simulations using the nested ocean models and the simulations using only the global ocean model. Finally, an individual-based biophysical model was built for SRL larval dispersal (Chapter 4), the larval survival during dispersal and the probability of pueruli successfully settling in suitable habitat were estimated (Chapter 5). Larvae were released throughout the species geographic range during the egg hatching period over release dates spanning twenty years. In addition to dispersal metrics, I report the connectivity matrix between 16 fishery management zones across the dispersal domain. Dominated by the large west-flowing currents in the study region, the main larval transport was from west to east. The highest rates of survival to settlement were seen in larvae that metamorphosed early during the competency window or within few hundred of km from their release locations. South Australian and Victorian fisheries were important larval sources for most other fisheries east from them, while Victorian and Tasmanian fisheries received the largest proportion of successful pueruli from all other fisheries. The highest self-recruitment rates were observed in New Zealand, Northern South Australia and Tasmania 2 fisheries. This study offers valuable insight into the applications and limitations of hydrodynamic models in larval dispersal modelling and calls for the development of highly-resolved coastal ocean models. The SRL larval dispersal model developed in this work provides new information on this species’ potential for dispersal and the predicted population connectivity can be used to inform new fishery policies and help improve management of the SRL stock.

This research examines traceability in the SRL export supply chain to investigate the use of low-cost image-based biometrics in lobster grading and identification. The SRL industry is a strategic export fishery contributing $250 million annually to the Australian economy with over 90% of its turnover coming from the Chinese market (prior to the COVID19 crisis). While the industry continues to grow, challenges have been identified that pose risks to the fishery's economic and environmental sustainability including: (1) Outbreaks of marine biotoxin and fish mortality/damage during transportation have raised food safety and quality concerns, (2) Product substitution via fraudulent business in export markets impacts the SRL premium brand, (3) The China Free Trade Agreement (ChAFTA) is changing requirements for food compliance regulations and, (4) consumer expectations for food quality, authenticity and provenance information on products is increasing. The SRL industry has identified product traceability as an important part of its response to these challenges. Traceability is broadly defined as the ability to track and trace food products at either item or batch level along part or all of the supply chain. Currently, some parts of the SRL supply chain do utilise product tracking such as barcodes and radio-frequency identification (RFID) tags in batch level traceability. However, item level traceability remains limited, with the granularity, form and availability of information on individual products, varying considerably along the chain. This is partly due to the high proportion of small SRL businesses continuing to rely on manual handling practices and paper-based traceability techniques. But it is also because of the continued relatively high cost of tools and techniques available to automate and digitise traceability data at the item level. Image-based biometrics deploying computer vision techniques have previously been trialled in individual animal tracking studies. These studies highlight the importance of understanding identifiable animal characteristics and the processes for image capture and analyses. In this research the key attributes of SRL captured and analysed relate to the lobster's size, weight, colour and spiny shell carapace patterns. Using these data, the feasibility of combining image processing and machine learning technologies to support automatic grading and individual identification of lobsters for processors, distributors and consumers in the SRL export supply chain were investigated. The research methodology involved a two-phase research strategy. Phase one identified key lobster characteristics and developed and tested image capture and analysis methods for both automatic grading and individual lobster identification. A key consideration for these methods is how to utilise low-cost equipment that would be readily accessible to SRL small businesses and consumers. Using the output of the automatic lobster grading, a physical prototype system was developed and tested to simulate an automatic grading operation in a fish processor. Based on the grading attributes and individual biometric characteristics selected and tested, a multimodal biometric identification model was developed. Building on these results, phase two focused on approaches to implementing traceability along the SRL supply chain through the design, testing and laboratory simulation of product tracking using a mobile application and verification server. The research design involved data collection at a Tasmanian fish processor where 8Mps Raspberry Pi cameras using a fixed distance and angle compiled a dataset of 4000 images of 200 lobsters. The lobster carapace was the "region of interest" (ROI) during the development of automatic grading and individual biometric identification. This ROI was extracted from lobster images using: (1) traditional image processing techniques and (2) convolution neural networks (CNNs). The preliminary results highlighted a pre-trained Mask-RCNN outperformed the traditional image processing techniques and the Mask-RCNN was utilised for individually analysing the grading attributes of size, weight (converted from size) and colour. These results were used to build and test a prototype grading system to simulate an automatic grading operation for use in a fish processor, integrating software, a conveyor belt, relay and cameras. In the analyses of individual techniques for lobster identification, colour histograms, texture and Siamese networks were tested and evaluated. Based on the outputs of the automatic grading and individual identification, a multimodal biometric identification model that combined lobster size, colour histogram, texture and deep learning results was developed and tested. However, the false-positive rate of this model remained high (64.5%) and this meant that the results achieved were insufficiently reliable for individual lobster identification when used as a standalone solution. For this reason, two hybrid biometric verification models for product tracking along the SRL supply chain were designed and tested. In both cases, lobster image identification was used as part of a layered hybrid authentication approach along with product tags attached on individual lobsters and/or boxes of lobsters. These approaches aimed to create '1-to-1' and/or '1-to-some' matching mechanisms. In both scenarios, a species-specific identification module was also developed and deployed to handle unmatched cases. This module was designed to enhance consumer confidence because it ensured that only genuine SRL products could be verified even if there were problems with individual verification based on tag identity number (ID) or lobster image. Using the main image library collected in Phase one, a biometric verification server and mobile application were used to demonstrate the operation of these two tracking models. The analyses on lobster grading yielded positive results in which size accuracy is 90% with a range of +/- 5% error compared with the actual sizes, and weight accuracy is 85% with a range of +/- 10% error compared with the actual weights. Colour classification also achieved a good result based on Euclidean distances between the average HSV colours of the ROIs and a base colour (black in this research) that helped identify a possible threshold to separate between the pale red and dark red groups. The testing with an automatic grading system also produced an important proof of concept where each lobster could be profiled with ID, images, size, weight, colour and other historical information. For lobster identification, the testing results with individual techniques including colour histogram, texture and Siamese network showed an ability to filter from one hundred objects down to a group of between 10-15 best candidates during the matching processes. The multimodal biometric model highlighted a further improvement of the matching process with the average of 5 candidates returned from the testing cases. However, the challenge of the false-positive rate in lobster identification remained high with 64.5% within this model. In the simulations for the two hybrid models, the false-positive rate showed a decrease to 0.35% for the '1-to-1' matching and 45% for '1-to-some' matching. For the species identification, the use of Support Vector Machine (SVM) for classifying between SRL and non-SRL products based on colour histogram of the carapace regions also achieved a positive result with 92% accuracy. The simulation of the product traceability also demonstrated a range of important functions for end-users supported by the central verification server and mobile application including image capture, lobster grading, barcode scanning and individual product verification. The results obtained across two phases demonstrated how low-cost computer vision technology can be utilised to analyse grading attributes of lobsters (RQ1) and highlighted the current capability of this technology in identifying individual lobsters (RQ2). The research also demonstrated approaches to using low-cost biometric grading and identification outcomes to improve the traceability performance along the SRL supply chain (RQ3). Based on the image-based biometric models developed and tested in this research several contributions can be identified: • From the technical viewpoint, the research strengthens the case for utilising lowcost computer vision in food traceability. Although the false-positive rate for the individual identification led to the deployment of hybrid traceability models, the multimodal biometric model developed does provide a platform for ongoing improvements to the accuracy of low-cost image-based biometric identification. • From the traceability viewpoint, the research offers an enhancement to conventional product tracking relying on physical tags. Importantly, the low-cost image-based biometric verification solutions developed support small SRL businesses to improve item tracking level based on the existing box-tagging practices. Additionally, the ability to integrate both the grading and identification functions into a mobile application offers direct traceability communication between overseas consumers and the Australian SRL exporters. • From the SRL industry viewpoint, the research provides industry stakeholders with a response to the concerns of food safety, quality and security. With the ability of verifying the authenticity and provenance of individual lobsters, the confidence of end consumers in the safety and authenticity of SRL products can be consolidated and the Australian sellers can be better protected from fraudulent activities in export markets. The approach also illustrates how Australian SRL businesses may be better prepared for any compliance requirements imposed by ChAFTA. Future work will be able to further improve identification techniques and testing in live environments and it is anticipated that low-cost tag-less image-based traceability will be available in the SRL and other seafood industry export supply chains in the near future.