Jasus Edwardsii Research Articles

Using marine protected areas to assess the status and recovery of the spiny lobster Jasus edwardsii fishery in the Hauraki Gulf, Aotearoa New Zealand

The value of no-take marine protected areas (MPAs) in providing fisheries-independent information to evaluate the status of adjacent fish stocks is increasingly being recognised. However, to ensure robust assessments of fisheries using this approach, MPAs need to be representative of the wider fished area and sampling should include multiple MPA and fished locations spanning the area of interest. The spiny lobster Jasus edwardsii fishery in Aotearoa New Zealand’s Hauraki Gulf has been in decline since the late 1990s, but latest stock estimates suggest a dramatic recovery following catch reductions in 2018. We compared J. edwardsii populations on shallow reefs (<20 m depth) in three marine reserves with six fished locations across the Hauraki Gulf to provide a fisheries-independent assessment of this important fishery and the degree of recovery following catch reductions. Region-wide surveys found that J. edwardsii populations within protected areas were dominated by large, legal-size individuals, whereas lobster in fished locations were mostly below or around legal-size. Total, vulnerable, and spawning stock biomass was 12-43 times higher within MPAs compared to fished locations. Overall, biomass at fished locations was <10% of that in reserves and there was little evidence of recovery following catch reductions. Our fisheries-independent data suggest that recent stock assessments have severely overestimated the recovery and state of lobster populations in the Hauraki Gulf and that populations on shallow reefs remain depleted. These findings highlight the critical need for fisheries-independent data and the value of MPA monitoring data in evaluating population status and recovery following fisheries management actions.

Spiny lobster recreational fisheries in Australia and New Zealand: An overview of regulations, monitoring, assessment and management

Spiny (rock) lobsters occur globally and, although harvest is dominated by commercial fisheries, it is important to account for recreational harvest in stock assessments and fisheries management. This paper provides a contemporary review of recreational fishing for five spiny lobster species in Australia and New Zealand. Each jurisdiction has established approaches for collecting data which best meet their information needs (telephone-diary or telephone-recall surveys, charter logbooks, tag reporting). Jurisdictions with specific spiny lobster licences (Western Australia, Tasmania) or mandatory reporting (charter logbooks in Western Australia, tag reporting in Victoria) use these registers as a sampling frame for annual reporting of participation, fishing effort, catch (numbers) and harvest (tonnes). All other jurisdictions use a general fishing licence or general population sampling frame for telephone-diary surveys to provide periodic reporting of catch and harvest. Annual participation in spiny lobster recreational fishing was highest in Western Australia (35,236 ± SE 626 fishers in 2022–23), followed by Tasmania (13,715 ± SE 1067 fishers in 2022–23) and Victoria (5516 fishers in 2020–21). Annual recreational harvest of all spiny lobster species, combined for the most recent data collection period in each jurisdiction, was 830 tonnes; consisting mostly of Western Rock Lobster (Panulirus cygnus) from Western Australia and Southern Rock Lobster (Jasus edwardsii) from Tasmania and New Zealand. This review illustrates the various spatial scales of monitoring, reporting and assessment in each jurisdiction. All monitoring provides information on catch and harvest, with some also reporting participation, effort, carapace length and non-catch related variables. The designs underlying these approaches vary from probability-based (opt-out) and census (mandatory), and it is important to understand the benefits and inherent biases of each. Understanding the parallels between jurisdictions offers valuable insights into how to cost-effectively monitor spiny lobster recreational fisheries and integrate this data into stock assessment and harvest strategies to support sustainable fisheries into the future.

Appendage damage effects on Southern Rock Lobster growth and mortality

Handling of crustaceans can result in injuries such as limb damage, reducing post-release survival and subsequent growth. Quantifying the impact of handling damage can provide insight into the effects of increased handling, which can occur when undersized animals are released by fishers or during translocations of animals between areas. We investigated the impact of handling on the Southern Rock Lobster (Jasus edwardsii) using three decades of scientific tag-recapture data from a no-fishing reserve. We used a Bayesian modeling approach with a modified Von Bertalanffy growth model which is robust to measurement error and Cormack-Jolly-Seber capture-recapture model to estimate growth and survival probability parameters. We found that even low levels of damage (1–4 appendages) can decrease growth by ∼ 10 % in the subsequent moult. Male lobsters suffered greater effects of handling-induced damage than did females, potentially due to the additional energy reserves available to brooding females.

Effect of collectors of the puerulus of the southern rock lobster Jasus edwardsii (Hutton, 1875) (Decapoda: Achelata: Palinuridae) on lobster catch rates in Tasmania, Australia

ABSTRACT The harvesting of the puerulus of rock, or spiny, lobsters for seed for aquaculture is a large industry throughout the Indo-Pacific region, and an increasing number of puerulus collectors are deployed. Little is known about the ‘crowding effect’ of the collectors and how catch might be influenced by their placement relative to each other owing to a lack of aggregate statistics for puerulus collectors in this region. The rock lobsters puerulus is also collected for fisheries research, as an index of puerulus catches on collectors can provide an indicator of recruitment strength. Both as a management tool and for commercial purposes, the collectors should act independently, not reducing or influencing catch rates on adjacent or other collectors in the area. We explored the independence of collectors of the puerulus of the southern rock lobster (Jasus edwardsii (Hutton, 1875)) using a long-term-data series from four sites on the east coast of Tasmania, Australia. Arrays of collectors were in grid and cross-shaped configurations, with individual collectors spaced three metres apart. Patterns in catches were examined using generalised least squares (GLS) modelling to determine if collectors filter pueruli as they swim shoreward, testing directional, neighbour, edge, and radial effects. The results revealed that there were no significant differences in puerulus settlement among collectors at this scale of spacing, meaning that arrays with collectors even as close as 3 m apart did not interfere with each other. This finding also suggests that collectors at this spacing only capture a small proportion of the available pueruli, allowing a significant number to pass through collector grids, with no significant reduction in catch of collectors further inshore. Such a result implies that it cannot be assumed that recruitment to a natural reef will be reduced by harvesting of pueruli with this type of collector and configuration.

Size‐specific reduction in kelp consumption by New Zealand urchins exposed to chemical cues from the red rock lobster

AbstractSea urchins can strongly reduce their mobility, exposure to predation, and feeding rates upon detection of chemical cues produced by predators, driving behavioral effects on grazing activity that may contribute to macroalgal community dynamics. However, the extent of chemically induced antipredator behaviors in urchins can vary by predator–prey species pair and ecological context and is therefore important to characterize in novel settings. Additionally, the effect of predator and prey size on urchin reactions to predator cues has rarely been considered, with the few existing examples yielding mixed conclusions. Here, we used a replicated split‐plot experiment to measure the effects of red rock lobsters (Jasus edwardsii) on consumption of macroalgae by the New Zealand sea urchin (Evechinus chloroticus) across a range of predator and prey body sizes. Overall, per‐capita consumption rates of kelp by urchins declined by 30% in the presence of lobsters, though feeding activity varied widely among individuals. Based on mass‐specific measurements of feeding rates, responses to predator cues appeared similar across all urchin sizes but only yielded distinguishable differences in the amount of kelp consumed in trials with larger urchins due to their considerably higher feeding capacity. Conversely, consumption rates of kelp by urchins had no apparent relationship with lobster size, likely due to chemical cue saturation in our experimental setting or a risk gradient that was insufficient to elicit a graded behavioral response. Our findings provide new evidence for a nonconsumptive effect of lobsters on feeding rates of an important grazer that can potentially reinforce the ecological role of this key predator in New Zealand kelp beds.

Adapting to climate change in a spiny lobster (Jasus edwardsii) fishery: A harvest strategy response

The complex lifecycle of spiny lobsters makes the species particularly vulnerable to the impacts of climate change. In south-eastern Australia, a regime shift in productivity was experienced during the late 1990s with evidence indicating that increased water temperatures had impacted on female size-of-maturity. Within the Southern Zone fishery of South Australia, this translated into low levels of egg production and sub-optimal fishery performance. In 2018, the harvest strategy for the fishery was reviewed with the primary focus of achieving a target percentage of unexploited egg production (%UEP) within an agreed timeframe. The proposed harvest strategy was based on a tabular harvest control rule, where catch per unit effort (CPUE) from the preceding season, as an indicator of lobster abundance, specified the following year’s total allowable commercial catch (TACC). To account for climate change impacts, the harvest strategy was assessed using a projection model where recruitment was sampled from post-regime shift years, thereby adopting a conservative approach to stock rebuilding. Results were assessed against projected trends in catch, CPUE and %UEP. In 2020, this harvest control rule was formally adopted and is now used in annual TACC setting. Observed values for key indicators have been closely aligned with projected estimates, with %UEP estimates approaching the target reference point. Specifically, %UEP has improved from 10% to 15% with the target projected to be achieved by the late 2020 s. Projections are sensitive to recruitment however, with a 21% lower recruitment scenario failing to reach target levels, thereby reinforcing the need to account for climate change impacts in harvest strategy testing.

Are we overthinking management zoning for the Tasmanian southern rock lobster fishery? A size of maturity approach

Crustacean fisheries, which are influenced by environmental drivers, can benefit from spatial management solutions. More size limit zones or other controls afford finer tuning of management solutions, but can also increase complexity in fishing operations. Defining management boundaries, and the feasibility of that compliance can be a balancing act between numerous stakeholders from commercial and recreational fishers, environmental groups and the science which informs such decisions. In Tasmania, the Southern Rock Lobster, SRL (Jasus edwardsii), exhibits dramatic growth variation across its range from the north to south of the fishery. A known proxy for growth is the Onset of Size of Maturity (SoM), which we have calculated for SRL at specific locations around Tasmania using a General Additive Model. Five assessment methods (objective functions: absolute difference and squared difference, both with and without equal zone weighting, and directionally penalised absolute difference) were used to identify possible management boundaries. Objective function inputs were the same for each method, and comprised of 100000 permutations of sampled SoM and spatial boundary locations for assessed regimes of 1–5 spatial boundaries. Statistical methods were applied to make zonation optimal for biology based on SoM. The results show that number of spatial zones required to yield “good” results did not require overly complex management solutions, nor unwieldy enforcement. Specifically, an investigation into two distinct spatial boundaries yielded solutions in which a critical, narrow boundary was complemented by a more flexibly located, secondary boundary for results of similar quality. The recommendations provided are in ranges of feasible locations, and likely to satisfy all stakeholders.

Puerulus settlement forecasting in a harvest strategy evaluation of the rock lobster fishery in South Australia

AbstractHarvest strategies are utilised in the management of fishery resources globally. Critical to their success is harvest strategy evaluation, whereby future performance is assessed through projection modelling. Using the observed relationship between a puerulus settlement index and model‐estimated recruitment, we evaluated a southern rock lobster (Jasus edwardsii) harvest strategy in South Australia. Short‐to‐medium puerulus settlement recruitment forecasting was incorporated into future projections of catch, catch per unit effort, and percent unexploited egg production (%UEP) during 2019–2022. Observed values of indicators that closely aligned with projected outputs indicated that puerulus forecasting underpinned reliable evaluation of future fishery performance. A key objective of the harvest strategy was to increase egg production in the fishery, with a 20% unexploited egg production targeted by 2036. The target was reached under the proposed strategy, but was sensitive to recruitment, thereby highlighting the need to consider climate change impacts in forecasting scenarios.

Lobster predation on barren-forming sea urchins is more prevalent in habitats where small urchins are common: a multi-method diet analysis

Context In Tasmania, Australia, the government’s response to range-extending, barren-forming longspined sea urchin (Centrostephanus rodgersii) includes rebuilding of southern rock lobster (Jasus edwardsii) stocks to increase predation. But lobster preference for native species and continued barren expansion challenges the control efficacy. Aims To determine the impact of lobster predation on C. rodgersii in different habitats. Methods Multi-method dietary analysis consisting of stomach contents, faecal DNA and stable isotopes was performed on 64 lobsters from four habitats varying in barren extent and density of urchins and lobsters. Key results C. rodgersii contributed to lobster diet in all barren habitats and was found in lobsters of every size class. Stable isotope and DNA analyses showed that C. rodgersii was more common in lobster diet than were targeted native species at incipient barren sites. Surprisingly, in extensive barrens C. rodgersii is less prominent in lobster diet. Conclusions Combined with site-specific urchin population data, our findings indicated that lobster predation may be less effective at sites where most C. rodgersii individuals have reached a size refuge than at sites dominated by small urchins. Implications Lobster predation may provide a useful control for smaller C. rodgersii, but top–down predatory control may be constrained at sites dominated by urchins that exceed the size suitable for lobster predation.

Addressing measurement error in lobster growth modelling

Mark and recapture tagging data is key for determining growth in species that are hard or impossible to age. Obtaining this data can be an expensive process, consequently there is an increasing reliance on measurements from non-scientists including commercial and recreational fishers and industry volunteers. A challenge with relying on data collection from these groups is that they are likely to have higher measurement errors. We demonstrate that this measurement error can introduce substantial bias. To account for this we developed a Bayesian model that is robust to a broad range of measurement uncertainty, which enables stochasticity in model outputs to be attributed to more appropriate causes, such as environmental drivers for further investigation. The model was tested through application to Southern Rock Lobster (SRL), Jasus edwardsii data. This was applied in two distinct areas in Tasmania, with different biological characteristics and data collection regimes. Application to this case study demonstrates that high measurement error can be problematic for commonly used methods, however our developed approach allows unbiased growth estimation from such datasets.

Data intermediate assessment: Examining the suitability of a novel depletion model for use in a spiny lobster fishery

The choice of assessment technique for a fishery with some, but not large amounts of data (intermediate data fishery), can be complex and depends on their suitability to the available data set(s) at an optimum resolution and appropriateness of model assumptions. Various “appropriate” techniques may have different output biases and understanding these is essential for robust fisheries management. We tested the suitability of an extended depletion model to assess a crustacean population using simulated data that replicated fishing patterns of a southern rock lobster (SRL) fishery in Western Australia. This simulation showed the model was appropriate for use and robust to assumptions including predetermined parameter choice and whether lobsters moulted during the fitted period. Although natural mortality was shown to have the biggest influence on model outputs (when compared to assumptions on moulting and fishing efficiency), its actual impact was minimal. When applied to the SRL resource off Western Australia, the model indicated that the stock has been heavily fished and reduced to almost 20 % of virgin levels. In recent years exploitation rates have declined due to external factors such as market access. This has resulted in a rapid increase in biomass, and model projections suggest that, with current catches, the biomass will return to 50 % of virgin levels within 10 years. Testing the modelling approach on a fishery with intermediate data provisions through simulation, has provided confidence in applying this technique to derive improved estimates for management.

Trophic discrimination factors and stable isotope variability in a captive feeding trial of the southern rock lobster Jasus edwardsii () (Decapoda: Palinuridae) in Tasmania, Australia

Abstract Trophic discrimination or fractionation factors (TDFs), such as ∆15N and ∆13C, are used in stable isotope mixing models to account for differences between source tissues (diet/prey) and consumer tissues (predator). We aimed firstly to obtain TDF values for a spiny lobster, the southern rock lobster Jasus edwardsii (Hutton, 1875), to better understand lobster diet in the wild and secondly to investigate variability in isotope signature within tissues of individuals and across a temporal scale to test if non-lethal sampling can be used in an ecological context. We conducted an 18-mo captive feeding trial with juvenile lobsters using three diet treatments and analysed dorsal and leg muscle, along with dorsal and leg exoskeleton for δ13C and δ15N values. Average TDFs for the three diet treatments were 3.86 ± 0.98‰ (∆13C) and 5.06 ± 0.65‰ (∆15N) for leg muscle, and 4.45 ± 1.04‰ (∆13C) and 4.36 ± 0.6‰ (∆15N) for dorsal muscle. When tested against wild lobsters and prey, these TDFs outperformed multi-taxa TDFs found in the literature. Isotope values from lobster leg muscle were not identical to associated dorsal muscle but the two were highly correlated, indicating that non-lethal sampling is acceptable. Values for exoskeleton isotope were significantly different from muscle, likely due to the exoskeleton not being in a constant state of growth and replacement, unlike the muscle tissue, which constantly incorporates new material. We conclude that our experimentally derived TDFs are suitable for mixing model analysis for J. edwardsii and when tested on a wild sample of lobsters they outperformed other TDFs reported in the literature. We show that non-lethal sampling using leg muscle is an appropriate sampling method, since this tissue is highly correlated to the commonly used dorsal muscle. This option for non-lethal sampling enhances the potential to widely sample wild populations or sample during industrial processing without the need to sacrifice whole animals.

Modelling spatial variation in an exploited species across marine reserve boundaries

Abstract An increase in exploited species within marine reserves is often expected to benefit adjacent fished areas through the movement or ‘spill‐over’ of exploited species across reserve boundaries. However, harvest at and near reserve boundaries can also decrease abundances inside reserves, forming ‘edge‐effects’. Spatial analysis of gradients in abundance across reserve boundaries have been used to interpret the extents of edge‐effects and spill‐over. While the shape of these gradients will vary depending on species mobility and fishing intensity on reserve boundaries, they have largely been assumed to be gradual and quantified using continuous modelling strategies. This study shows that continuous modelling strategies can lead to overestimations of spill‐over and edge‐effects by underfitting the rapid transition in abundance that can occur from reserve to fished areas. The abundances of spiny lobster (Jasus edwardsii) across the boundaries of two north‐eastern New Zealand marine reserves were quantified using catch survey data collected over 2 years. Several modelling approaches were used, and the predictive performance of each approach was compared. Abrupt changes in lobster abundances were found across reserve boundaries and were best represented with models that incorporated a stepwise function across boundaries or where data from reserve and fished areas were modelled independently. Despite the mobile nature of this species, we found little evidence of edge‐effects and spill‐over within and adjacent to the surveyed marine reserves, which may reflect the low population status within these reserves. In contrast, standard continuous modelling approaches overestimated the extent of edge‐effects and spill‐over in both marine reserves. Policy implications. This study shows how accurate assessments of edge‐effects and spill‐over can be used to evaluate the effectiveness of existing marine reserves in protecting exploited species. These findings emphasise the importance comparing several different modelling strategies when evaluating edge‐effects and spill‐over to ensure appropriate model fits. Although modelling approaches such as generalised additive models present a simple solution to exploring spatial variation in ecological data, we emphasise the importance of questioning the applicability of such strategies when assessing variation across areas of rapid change such as protected area boundaries.

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.

The efficacy of electrical stunning of New Zealand rock lobster (Jasus edwardsii) and freshwater crayfish (Paranephrops zealandicus) using the Crustastun™.

Large numbers of decapod crustacea are farmed and harvested globally for human consumption. Growing evidence for the capacity of these animals to feel pain, and therefore to suffer, has led to increased concern for their welfare, including at slaughter. In New Zealand, decapod crustacea are protected by animal welfare legislation. There is a requirement that all farmed or commercially caught animals of these species killed for commercial purposes are first rendered insensible. The aim of this study was to evaluate the efficacy of the Crustastun™, a commercially available bench-top electrical stunner, in two commercially important New Zealand crustacean species; the rock lobster (Jasus edwardsii) and kōura (freshwater crayfish [Paranephrops zealandicus]). Animals were anaesthetised via intramuscular injection of lidocaine and instrumented to record the electrical activity of the nervous system, prior to being stunned according to the manufacturer's instructions. Stunning efficacy was determined by analysing neural activity and observing behaviour post stunning. All ten P. zealandicus and three J. edwardsii appeared to be killed outright by the stun. Of the remaining J. edwardsii, six exhibited some degree of muscle tone and/or slow unco-ordinated movements of the limbs or mouthparts after stunning, although there was no recovery of spontaneous or evoked movements. One J. edwardsii was unable to be stunned successfully, likely due to its very large size (1.76kg). None of the successfully stunned animals showed any evidence of return of awareness in the five minutes following stunning. It was concluded that the Crustastun™ is an acceptable method for killing P. zealandicus and for stunning all but the largest J. edwardsii.

Marine protected areas provide unfished reference information to empirically assess fishery status

Fisheries stock assessments typically determine stock-status using estimates of unfished biomass generated from fisheries dependent data. Due to limitations and biases in these data, modelled unfished estimates are reliant on assumptions regarding stock ecology. This can lead to a high degree of uncertainty in estimates of unfished biomass and can compromise sustainable management. We propose using the biomass of exploited species in no-take marine protected areas (marine reserves) as a proxy for unfished biomass to empirically assess stock status. Marine reserves provide contemporary examples of exploited populations in the absence of fishing under current conditions. Using lobster (Jasus edwardsii) potting and diver-based survey data from 2018 and 2019 we calculated fisheries relevant metrics from inside and outside two north-eastern New Zealand marine reserves. Based on marine reserve reference points, we found spawning stock catch rates and biomass of lobster in adjacent fished areas were 3 % and 2 % of unfished levels. Comparability of potting and dive survey estimates validates using dive survey data to estimate stock status, while differences in population information between survey methods highlights the limited ability of catch data to accurately inform on sub-legal abundances. Overall, our fisheries-independent approach suggests the fished population is at lower levels than latest estimates for the wider fishery and demonstrates how marine reserves can provide information on key parameters which can be incorporated into traditional stock assessments. Planning for future marine reserves should consider the value of such areas as tools to help manage fisheries in addition to protecting exploited species.

Disentangling genetic from environmental effects on phenotypic variability of southern rock lobster (Jasus edwardsii) postlarvae.

Environmental conditions experienced during the larval dispersal of marine organisms can determine the size-at-settlement of recruits. It is, therefore, not uncommon that larvae undergoing different dispersal histories would exhibit phenotypic variability at recruitment. Here, we investigated morphological differences in recently settled southern rock lobster (Jasus edwardsii) recruits, known as pueruli, along a latitudinal and temporal gradient on the east coast of Tasmania, Australia. We further explored whether natural selection could be driving morphological variation. We used double digest restriction site-associated DNA sequencing (ddRADseq) to assess differences in the genetic structure of recently settled recruits on the east coast of Tasmania over 3 months of peak settlement during 2012 (August-October). Phenotypic differences in pueruli between sites and months of settlement were observed, with significantly smaller individuals found at the northernmost site. Also, there was a lack of overall genetic divergence; however, significant differences in pairwise FST values between settlement months were observed at the southernmost study site, located at an area of confluence of ocean currents. Specifically, individuals settling into the southernmost earlier in the season were genetically different from those settling later. The lack of overall genetic divergence in the presence of phenotypic variation indicates that larval environmental history during the dispersal of J. edwardsii could be a possible driver of the resulting phenotype of settlers.

Impacts of sub‐optimal water quality on the haemolymph biochemistry, immune status and condition of post‐harvest Southern Rock Lobsters (Jasus edwardsii)

AbstractPalinurid rock (or spiny) lobsters constitute valuable seafood fisheries around the world. Post‐harvest mortality can have a substantial economic impact on the value of these fisheries and damage the brand identity of an otherwise fungible commodity. In this study, sudden, large‐scale mortalities in the Australian Rock Lobster industry were investigated through comprehensive haemolymph biochemistry panels, measurements of immune status and nutritional condition. A cohort of lobsters (n = 25) was sampled over a 4‐week period at a commercial processing facility, with the final sample occurring during a mortality event. A comparison of 22 biochemical parameters, including electrolytes, minerals, ions, metabolites and enzymes, showed a notable disruption in osmoregulation, protein content and enzymes during weeks 3 and 4 of the study. Haemocyte counts showed a decline in circulating haemocytes by the time of the mortality event along with a shift in the proportion of hyalinocytes to granulocytes favouring the former. The condition index was variable over the sampling schedule, possibly linked to observed incidences of cannibalism, with no evidence of an overall low condition that would explain mortalities. The lobsters sampled in this study did not show any consistent or progressive changes in biochemistry that may indicate a pathogen or disease as a causative agent. Rather, analysis of the water quality within the facility suggested that mortality was due to sub‐optimal water quality characterized by a combination of two factors, a substantial decrease in the pH and potential nitrogen toxicity, that caused a physiological response comprised of an ion imbalance, altered enzyme activity and, ultimately, mortality. These results offer a comprehensive characterization of the impact of unexplained morbidity on the biochemistry and physiology of lobsters, illustrate the harm of sub‐optimal aquaculture practices and highlight the need for a better understanding of aquaculture practices and their effects on economically important seafood industries.

The impact of seismic survey exposure on the righting reflex and moult cycle of Southern Rock Lobster (Jasus edwardsii) puerulus larvae and juveniles

Anthropogenic aquatic noise is recognised as an environmental pollutant with the potential to negatively affect marine organisms. Seismic surveys, used to explore subseafloor oil reserves, are a common source of aquatic noise that have garnered attention due to their intense low frequency inputs and their frequent spatial overlap with coastal fisheries. Commercially important Southern Rock Lobster (Jasus edwardsii) adults have previously shown sensitivity to signals from a single seismic air gun. Here, the sensitivity of J. edwardsii juveniles and puerulus to the signals of a full-scale seismic survey were evaluated to determine if early developmental stages were affected similarly to adults, and the range of impact. To quantify impact, lobster mortality rates, dorsoventral righting reflex and progression through moult cycle were evaluated following exposure. Exposure did not result in mortality in either developmental stage, however, air gun signals caused righting impairment to at least 500 m in lobsters sampled immediately following exposure, as had previously been reported in adults with corresponding sensory system damage following exposure. Impairment resulting from close range (0 m) exposure appeared to be persistent, as previously reported in adults, whereas juveniles exposed at a more distant range (500 m) showed recovery, indicating that exposure at a range of 500 m may not cause lasting impairment to righting. Intermoult duration was (time between moults) significantly increased in juveniles exposed at 0 m from the source, indicating the potential for slowed development, growth, and physiological stress. These results demonstrate that exposure to seismic air gun signals have the potential to negatively impact early life history stages of Southern Rock Lobsters. The similarity of both the impacts and the sound exposure levels observed here compared to previous exposure using a single air gun offer validation for the approach, which opens the potential for accessible field-based experimental work into the impact of seismic surveys on marine invertebrates.

Cardiac mitochondrial energetics of the Australasian red spiny lobster, Jasus edwardsii, when exposed to isoeugenol within the commercial anaesthetic AQUI-S.

The anaesthetic isoeugenol has been used as metabolic suppressant for commercial transport of live lobsters in order to decrease energy expenditure and improve survival. Given the central role of mitochondria in metabolism and structural similarities of isoeugenol to the mitochondrial electron carrier coenzyme Q, we explored the influence on mitochondrial function of isoeugenol. Mitochondrial function was measured using high-resolution respirometry and saponin-permeabilised heart fibres from the Australasian red spiny lobster, Jasus edwardsii. Relative to vehicle (polysorbate), isoeugenol inhibited respiration supported by complex I (CI) and cytochrome c oxidase (CCO). While complex II (CII), which also reduces coenzyme Q, was largely unaffected by isoeugenol, respiration supported by CII when uncoupled was depressed. Titration of isoeugenol indicates that respiration through CI has a half-maximal inhibitory concentration (IC50) of 2.4±0.1 µmoll-1, and a full-maximal inhibitory concentration (IC100-) of approximately 6.3 µmoll-1. These concentrations are consistent with those used for transport and euthanasia of J. edwardsii and indicate that CI is a possible target of isoeugenol, like many other anaesthetics with quinone-like structures.