Jasus Edwardsii Research Articles

Predicting transport survival of brindle and red rock lobsters Jasus edwardsii using haemolymph biochemistry and behaviour traits

Mortality events during live transport of Jasus edwardsii rock lobsters are common around the time of season openings in Tasmania, with lobsters from deeper fishing areas with pale shell colouration (brindle) being perceived as more susceptible than shallow-water, red-coloured (red) lobsters. The aims of this study were to assess and predict the vulnerability of brindle and red lobsters to extended emersion exposure using pre- and post-emersion data which included 28 haemolymph biochemical parameters and 5 behaviour traits.No effect of lobster shell colour on haemolymph biochemistry, behaviour traits and their vulnerability to emersion was found. A combined survival of 97% after 40h and 57% after 64h in a first experiment, and 37% after 64h in a second experiment, was observed. Behaviour traits (i.e., righting response, tail flips and three reflex behaviours) were poor indicator of survival. Haemolymph parameters were either unaffected by emersion (e.g., Brix index, protein and lipids), affected by emersion but not associated with mortality (e.g., total haemocyte counts, calcium, magnesium, bicarbonate, glucose and uric acid), or associated with mortality following a recovery period (e.g., pH, the sodium to potassium ratio, urea, and the activity of amylase). A build-up of anaerobic end-products and nitrogenous waste most likely resulted in the mortality. A model based on lobster size and the pre-emersion concentration of haemolymph bicarbonate and haemocyanin was found to be a useful indicator of future survival. This study provides promising leads towards the development of a blood based vulnerability test for live crustacean prior transport.

Reef Sound as an Orientation Cue for Shoreward Migration by Pueruli of the Rock Lobster, Jasus edwardsii.

The post-larval or puerulus stage of spiny, or rock, lobsters (Palinuridae) swim many kilometres from open oceans into coastal waters where they subsequently settle. The orientation cues used by the puerulus for this migration are unclear, but are presumed to be critical to finding a place to settle. Understanding this process may help explain the biological processes of dispersal and settlement, and be useful for developing realistic dispersal models. In this study, we examined the use of reef sound as an orientation cue by the puerulus stage of the southern rock lobster, Jasus edwardsii. Experiments were conducted using in situ binary choice chambers together with replayed recording of underwater reef sound. The experiment was conducted in a sandy lagoon under varying wind conditions. A significant proportion of puerulus (69%) swam towards the reef sound in calm wind conditions. However, in windy conditions (>25 m s-1) the orientation behaviour appeared to be less consistent with the inclusion of these results, reducing the overall proportion of pueruli that swam towards the reef sound (59.3%). These results resolve previous speculation that underwater reef sound is used as an orientation cue in the shoreward migration of the puerulus of spiny lobsters, and suggest that sea surface winds may moderate the ability of migrating pueruli to use this cue to locate coastal reef habitat to settle. Underwater sound may increase the chance of successful settlement and survival of this valuable species.

Accounting for habitat and seafloor structure characteristics on southern rock lobster (Jasus edwardsii) assessment in a small marine reserve

Where to place marine protected areas (MPAs) and how much area they should cover are some of the most basic questions when designing MPAs. Based on the theory of island biogeography, larger reserves are likely to protect more species and individuals but smaller reserves have been shown to positively influence populations. In this study, we assess a localised population of the ecologically and economically important southern rock lobster (Jasus edwardsii) inside and outside a small reserve. We used standardised fishery assessment trapping methods to sample J. edwardsii populations inside a reserve and an adjacent area outside the reserve. The population characteristics of the captured individuals were compared inside and outside the reserve using t tests (male size, female size, number of reproductive females, number of individuals and biomass), and we found that there were significantly greater numbers and larger individuals and biomass inside the reserve. However, many assessments of MPA effectiveness are confounded by differences in habitat. To account for possible differences in habitat, we collected multibeam bathymetry data to allow us to characterise seafloor structure and video data to assign each sampling location to a biotope class based on macroalgae assemblages. Then, using generalised linear models (GLMs), we assessed differences in populations while accounting for habitat. The GLMs revealed that there was still a significant difference in populations inside the reserve despite habitat differences inside and outside the reserve. We demonstrate a methodological approach to provide a baseline data set to assess MPA effectiveness through time and measure how habitat may respond to indirect consequences of fishing or other human impacts at the species or ecosystem level. We also highlight some of the limitations in sampling design and data availability common in MPA studies and resulting implications for assessment.

Spatial variation in mortality by in‐pot predation in the Tasmanian rock lobster fishery

AbstractThe capture of target species using pots or traps can be affected by interactions that occur inside fishing gear. In the Tasmanian southern rock lobster (Jasus edwardsii) fishery (SRLF), predation by octopus is known to vary spatially, assumed to be in response to different environmental and ecological conditions. However, these effects are not well understood and there is concern that changes in the system, as a result of climate change, may alter the spatial distribution and extent of octopus predation. Using fishery‐dependent commercial time series data (2000–2011), we first examined how in‐pot lobster mortality by octopus predation varied across fishing areas at inter‐ and intra‐annual scales. These spatial and temporal patterns were examined using dynamic regression models (DRM) using lagged variables of lobster abundance (lobster catch per unit effort, CPUE), fishing effort (potlifts) and environmental variables (sea surface temperature, SST). This demonstrated that in‐pot mortality in most areas was strongly affected by the current lobster CPUE (indicating an instantaneous direct impact), whereas fishing effort and SST differed spatially in terms of lag selection and correlation sign. Most eastern Tasmanian areas showed a stronger effect of fishing effort rather than SST, with the opposite pattern along the west coast. We provide the first classification of SRLF stock assessment areas based on predation risk level and identify the explanatory fishing and environmental factors.

The Influence of Mark-Recapture Sampling Effort on Estimates of Rock Lobster Survival.

Five annual capture-mark-recapture surveys on Jasus edwardsii were used to evaluate the effect of sample size and fishing effort on the precision of estimated survival probability. Datasets of different numbers of individual lobsters (ranging from 200 to 1,000 lobsters) were created by random subsampling from each annual survey. This process of random subsampling was also used to create 12 datasets of different levels of effort based on three levels of the number of traps (15, 30 and 50 traps per day) and four levels of the number of sampling-days (2, 4, 6 and 7 days). The most parsimonious Cormack-Jolly-Seber (CJS) model for estimating survival probability shifted from a constant model towards sex-dependent models with increasing sample size and effort. A sample of 500 lobsters or 50 traps used on four consecutive sampling-days was required for obtaining precise survival estimations for males and females, separately. Reduced sampling effort of 30 traps over four sampling days was sufficient if a survival estimate for both sexes combined was sufficient for management of the fishery.

Protein hydrolysates produced from rock lobster (Jasus edwardsii) Head: emulsifying capacity and food safety.

Lobster protein hydrolysates (LPH) were produced by an enzymatic process using a proteinase Alcalase, and a chemical process at strong alkaline condition (pH of 14), from rock lobster head (RLH), respectively. The chemical process recovered about 30% more protein than the enzymatic process (84.9% recovery of total protein in RLH by the chemical process and 54.5% recovery of total protein in RLH by the enzymatic process). The emulsifying capacity of LPH produced by the chemical process (69.7 m2/g) was significantly higher than the emulsifying capacity of the LPH produced by the enzymatic process (20.7 m2/g), and also exceeds the emulsifying capacity of cow gelatine (50.3 m2/g), a commercial emulsifier in the food industry. LPH produced by the chemical process possess 30.3% essential amino acids. This content is comparable with the essential amino acid content of fish protein, a commonly recognized food resource for essential amino acid supplement for human. The content of heavy metals, including inorganic arsenic, of LPH is lower than the standard levels regulated by Food Standard Australia and New Zealand (FSANZ). These results demonstrated the potential value of LPH used as a safe emulsifier with significant nutritional value for the food industry.

Seismic air gun exposure during early-stage embryonic development does not negatively affect spiny lobster Jasus edwardsii larvae (Decapoda: Palinuridae).

Marine seismic surveys are used to explore for sub-seafloor oil and gas deposits. These surveys are conducted using air guns, which release compressed air to create intense sound impulses, which are repeated around every 8–12 seconds and can travel large distances in the water column. Considering the ubiquitous worldwide distribution of seismic surveys, the potential impact of exposure on marine invertebrates is poorly understood. In this study, egg-bearing female spiny lobsters (Jasus edwardsii) were exposed to signals from three air gun configurations, all of which exceeded sound exposure levels (SEL) of 185 dB re 1 μPa2·s. Lobsters were maintained until their eggs hatched and the larvae were then counted for fecundity, assessed for abnormal morphology using measurements of larval length and width, tested for larval competency using an established activity test and measured for energy content. Overall there were no differences in the quantity or quality of hatched larvae, indicating that the condition and development of spiny lobster embryos were not adversely affected by air gun exposure. These results suggest that embryonic spiny lobster are resilient to air gun signals and highlight the caution necessary in extrapolating results from the laboratory to real world scenarios or across life history stages.

Stakeholder management of the New Zealand red rock lobster (Jasus edwardsii) fishery

The history and management of the New Zealand fishery for the rock lobster Jasus edwardsii is described. The fishery was essentially open-access to 1979, with limited input controls. Access was strictly limited from 1979 to 1989, but effort increased to a peak in 1985, when the fishery was fully exploited. Early stock assessments suggested over-exploitation. Quotas were introduced in 1990 and catches were reduced from their then mean levels to promote stock rebuilding. Subsequently, the commercial fishing industry has exercised stewardship initiatives to maintain stocks. Operational management procedures have been developed and introduced since 1996. While overall catch is similar to 1990 levels, catch per unit of effort has more than doubled. Successes and challenges for future management are discussed.

Acute sublethal toxicity of MV Rena contaminants (heavy fuel oil, oil dispersant and cryolite) to finfish and rock lobster

ABSTRACTThe wreck of the MV Rena in October 2011 discharged large quantities of potentially toxic materials in the coastal marine environment of the Bay of Plenty, New Zealand. We evaluated sublethal effects of the water soluble fractions of physically and chemically dispersed heavy fuel oil (HFO) and the water soluble fraction of cryolite on the haematology of subadult or adult snapper (Chrysophrys auratus), spotted wrasse (Notolabrus celidotus) and red rock lobster (Jasus edwardsii). Small but transient effects occurred, the most significant of which were changes in circulating immune cell populations in fish and lobster that recovered by the conclusion of a 96-h exposure period. No post-exposure effects were observed during a 10-day recovery in toxicant-free seawater. Corexit 9500 oil dispersant increased polycyclic aromatic hydrocarbon (PAH) uptake from HFO in fish and lobster by around two-fold and four-fold, respectively, and caused a larger change in immune cell abundance in snapper than exposure to HFO alone. While depuration of PAHs was more rapid in fish than lobster, significantly elevated PAH levels were still evident after 10 days of depuration.

The Environmental Impact of Two Australian Rock Lobster Fishery Supply Chains under a Changing Climate

SummaryUnderstanding the potential future impacts of climate change along the supply chain for highly traded fisheries products can inform choices to enhance future global seafood security. We examine the supply chains of the Australian tropical rock lobster fishery (TRL) and southern rock lobster fishery (SRL), with similar destination markets but different catch methods and fishing communities. A boat‐to‐market analysis allows for comparison and illustration of the effects of single supply‐chain aspects. We used life cycle assessment to provide an overview of the environmental footprint, expressed as global warming potential (GWP), eutrophication, and cumulative energy demand, for two lobster products: live animals and frozen tails. The export phase contributed 44% and 56% of GWP of live‐weight lobster for SRL and TRL, respectively. The SRL fishery currently produces 68% of the combined 1,806.7 tonnes of lobster product and 78% of the combined global warming for the two fisheries over the whole supply chain. We develop climate adaptation options that: (1) reduce the overall footprint; (2) consider alternative supply‐chain strategies (e.g., reduce cost); and (3) predicted impact of future climate change. Adaptation options include: more direct export routes and change in the export transport mode. Value adding and product differentiation, which can level out seasonality and thus spread risk, is likely to become increasingly important for both increases and decreases in predicted climate‐induced abundance of fish species.

Microwave-Intensified Enzymatic Deproteinization of Australian Rock Lobster Shells (Jasus edwardsii) for the Efficient Recovery of Protein Hydrolysate as Food Functional Nutrients

Enzymatic deproteinization of lobster shells is an important step in developing a novel biorefinery process for the recovery of both protein and chitin. This study aimed to develop an efficient enzymatic deproteinization of lobster shells for protein recovery while providing the residual fraction suitable for further chitin recovery. In comparison with conventional incubation, the microwave-intensified enzymatic deproteinization (MIED) of Australian rock lobster shells significantly improved the deproteinization degree from 58 to 85.8 % and reduced the residual protein content from 96.4 to 65.4 mg/g, respectively. The protein hydrolysate produced by MIED had excellent functionality (solubility 91.7 %, water absorption 32 %, oil absorption 2.3 mL/g, foaming 51.3 %, emulsification 91.3 %) and high nutritional quality (34 % essential amino acids, 45.4 mg/g arginine, lysine/arginine ratio 0.69) with potential applications for food industry. With the considerably low residual protein, the MIEDs are suitable for further chitin recovery.

Handled with care: Minimal impacts of appendage damage on the growth and productivity of the southern rock lobster (Jasus edwardsii)

The capture, handling and release of invertebrates such as lobsters during commercial fishing operations can lead to physiological changes such as reduced growth and impaired reproduction. In particular, damage to appendages can reduce the exploitable biomass available to fishers as moulting lobsters expend energy resources regrowing limbs at the expense of increasing in size. To assess the effect of injuries on the growth of male and female lobsters smaller than the legal minimum size (undersize), a Bayesian hierarchical approach was taken to fit the parameters of the von Bertalanffy growth equation to mark-recapture observer data from southern stock assessment areas (SSAAs) of the Tasmanian southern rock lobster (TSRL) fishery in Australia. While the effect of handling damage on the growth of undersize females could not be distinguished from zero because of small growth increments, the impact on males was marked, with damage to antennae or legs estimated to have a similar proportional impact on growth of 7% (0–16%, 95% CI) and 7% (0–14%, 95% CI) respectively. Damage to both antennae and legs had a greater estimated proportional impact on growth of 40% (24–57%, 95% CI). Despite the substantial reductions in predicted growth caused by the loss of antennae and/or legs, fewer than 6% of undersize male lobsters had these types of injuries. With an estimated 4.22±0.4 (mean±95% CI) million lobsters discarded annually between 2001 and 2010 from SSAAs, annual lost productivity and revenue from slower growth was predicted to be 1.6 tonnes and AUD $72,905 respectively in the TSRL fishery. The overall impact of damage on male lobsters was less than 1% of the total allowable catch and revenue for the TSRL fishery in 2010. Mortality among damaged lobsters was estimated at 3.9% from SSAAs for a total productivity loss of 22.1 tonnes in the TSRL fishery. These results highlight the effectiveness of the fishing method, sorting procedures, as well as management measures (escape gaps) and the biology of the species in reducing excessive amounts of handling damage in the TSRL fishery.

Predation Risk within Fishing Gear and Implications for South Australian Rock Lobster Fisheries

Depredation of southern rock lobster (Jasus edwardsii) within fishing gear by the Maori octopus (Pinnoctopus cordiformis) has economic and ecological impacts on valuable fisheries in South Australia. In addition, depredation rates can be highly variable resulting in uncertainties for the fishery. We examined how in-pot lobster predation was influenced by factors such as lobster size and sex, season, fishing zone, and catch rate. Using mixed modelling techniques, we found that in-pot predation risk increased with lobster size and was higher for male lobsters. In addition, the effect of catch rate of lobsters on predation risk by octopus differed among fishing zones. There was both a seasonal and a spatial component to octopus predation, with an increased risk within discrete fishing grounds in South Australia at certain times of the year. Information about predation within lobster gear can assist fishery management decision-making, potentially leading to significant reduction in economic losses to the fishery.

Lobster in a bottle: a novel technique for observing the predation of juvenile spiny lobster (Jasus edwardsii)

Determining the impact of predators on juvenile spiny lobsters living on reefs is important for understanding recruitment processes that ultimately help determine the size of economically important lobster populations. The present study describes a novel approach for observing attempted predation on live juvenile spiny lobster (Jasus edwardsii) in situ, by presenting the lobster in a transparent container that was lit with infrared light to enable continuous monitoring, even at night, by video recording. This technique can be used to provide valuable information on overall relative predation pressure from comparative locations and habitats, as well as identify potential predators, their mode of predation, and the timing of their of predation activity. For example, predation attempts on juvenile J. edwardsii by the spotted wrasse (Notolabrus celidotus) were recorded only from 0500 to 1400 hours (daytime) and from 1900 to 2100 hours (dusk), whereas the activity by the northern conger eel (Conger wilsoni) was observed only for the period between 2100 and 0200 hours (nocturnal). This method of assessing predation of juvenile lobsters provides considerable advantages over previously used tethering methods, by allowing continuous observations over a long time period (≥24h), including night time, while also eliminating experimental mortality of juvenile lobsters.

From certification to recertification the benefits and challenges of the Marine Stewardship Council (MSC): A case study using lobsters

This paper compares two lobster fisheries, the Western Australian rock lobster (Panulirus cygnus) and the Mexico Baja California red rock lobster (Panulirus interruptus) that have been certified and re-certified by the Marine Stewardship Council (MSC), and compares the benefits and challenges associated with the certification process. Both fisheries have had similar conditions imposed to address deficiencies identified in the assessment process. The conditions included a better understanding of target stock status, improving monitoring and reporting of bycatch and Endangered Threatened and Protected species (ETPs), improving the understanding of the potential impacts of fishing on the ecosystem and implementing research plans. Providing the data to address these conditions was both expensive and time consuming but improved the understanding of these fisheries. Currently, MSC certified lobster accounts for approximately 20% of global lobster harvest. However, there is no evidence of a price premium for either Western Australian or Mexican Baja California lobster. At present, the vast majority of both lobster species sold are not tagged with the MSC logo due to the additional cost associated with its use. Despite the differences in species, landings and value, the Western Australian rock lobster and Mexican Baja California red rock lobster fisheries have had similar experiences in the benefits and challenges of the MSC process. In the case of the two lobster fisheries examined here, and undoubtedly in a number of other fisheries around the world where domestic or international market recognition of MSC is not high, the social and political benefits of certification far outweigh any economic incentive.

Inducers of settlement and moulting in post-larval spiny lobster.

The rapid and often remote location of suitable habitats used by migrating organisms is often critical to their subsequent recruitment, fitness and survival, and this includes in the marine environment. However, for the non-feeding post-larval stage of spiny lobsters, effective settlement cues for habitat selection are critical to their success but are poorly described. Therefore, the current study examined whether acoustic and substrate cues have the potential to shorten the time to moulting and affect their subsequent nutritional condition in the pueruli of the southern spiny lobster, Jasus edwardsii. Individuals moulted to first instar juveniles up to 38% faster when exposed to the underwater sound from two types of typical settlement habitat (coastal kelp- and urchin-dominated reefs) compared to those with no underwater sound. The settlement delay in the post-larvae without underwater sound also resulted in juveniles in poorer survival and nutritional condition as measured by their protein and lipid contents. In a separate experiment, post-larvae presented with seaweed and rock substrates were found to complete settlement and moult to juvenile by as much as 20% faster compared to those on the sand and control treatments. Overall, the results are the first to demonstrate that the pueruli of J. edwardsii have the ability to detect and respond to underwater sound, as well as determining that both acoustic and substrate cues play a role in modulating physiological development during settlement.

Trade-offs between invertebrate fisheries catches and ecosystem impacts in coastal New Zealand

Abstract Invertebrate catches are increasing globally following the depletion of many finfish stocks, yet stock assessments and management plans for invertebrates are limited, as is an understanding of the ecosystem effects of these fisheries. Using an ecosystem modelling approach, we explored the trade-offs between invertebrate catches and their impacts on the associated ecosystem on the south coast of Wellington, New Zealand. We simulated exploitation of lobster (Jasus edwardsii), abalone (Haliotis australis, H. iris), and sea urchin (Evechinus chloroticus) over a range of depletion levels—from no depletion to local extinction—to estimate changes in target catches and associated effects on other species groups, trophic levels, and benthic and pelagic components. Exploitation of lobster showed the strongest ecosystem effects, followed by abalone and urchin. In all three fisheries, the current exploitation rate exceeds that which produces maximum sustainable yield, with considerable ecosystem effects. Interestingly, a reduced exploitation rate is predicted to increase target catches (and catch-per-unit-effort), thereby strongly reducing ecosystem effects, a win–win situation. Our results suggest that invertebrate exploitation clearly influences ecosystem structure and function, yet the direction and magnitude of responses depend on the target group and exploitation rate. An ecosystem-based fisheries management approach that includes the role of invertebrates would improve the conservation and management of invertebrate resources and marine ecosystems on broader scales.

The effects of pre-digested protein sources on the performance of early–mid stage Panulirus ornatus phyllosoma

Phyllosoma of the tropical spiny rock lobster, Panulirus ornatus, possess a rudimentary digestive system with a limited capacity to digest large protein molecules. As such, to foster the successful aquaculture of this species, research into dietary requirements should place a focus on feed ingredients aligned with digestive capacity. Thus, the aim of the present study was to assess the effects of two protein pre-digestion treatments: acid denaturation and enzyme hydrolysis, on a regular fishmeal ingredient in a novel formulated diet for early–mid stage P. ornatus phyllosoma (Stages III–VIII). Three iso-nitrogenous, iso-lipidic and iso-energetic diets were formulated with 100% of protein originating from intact fishmeal (IFM), acid-denatured fishmeal (DFM) or enzyme hydrolysed fishmeal (HFM) and fed to early–mid stage phyllosoma for a period of 35-days. Growth performance metrics were all significantly higher in phyllosoma receiving the HFM treatment compared to the DFM and IFM treatments. Phyllosoma fed the HFM diet also had the most advanced development stages, with a significantly greater proportion of individuals reaching Stage VII (2). No significant differences were detectable in either the protein-bound or FAA composition of phyllosoma across all treatments, suggesting that the superior growth performance of the HFM fed phyllosoma was the result of an increased abundance of intermediate, shorter chain dietary peptides. The present study suggests that enzyme hydrolysed fishmeal is a superior protein ingredient for artificial diets and most closely resembles the requisite dietary protein format for P. ornatus phyllosoma.

Estimating survival of rock lobsters from long-term tagging programmes: how survey number and interval influence estimates

Abstract A long-term tagging dataset on southern rock lobster (Jasus edwardsii) conducted at the Crayfish Point Scientific Reserve near Hobart, Tasmania, Australia, was used to determine how survey number and survey duration affected the precision of survival estimates of male and female lobsters to ensure sustainable exploitation of the population. Tagging surveys were undertaken twice yearly during 2000–2003 with unequal time-intervals between surveys and then once a year with equal time-intervals during 2004–2012 during the January–February period. The most parsimonious Cormack–Jolly–Seber model for estimating survival of lobsters was dependent on (i) timing of the tagging and recapture surveys, (ii) time between consecutive recapture surveys, and (iii) gender. The number of surveys required to provide a precise survival probability varied with gender and time between recapture surveys. For surveys where there was unequal time between recapture surveys, seven and five surveys were required for female and male lobsters, respectively, whereas only five surveys were required when annual surveys were undertaken. Thus, lobster tagging projects using annual surveys should ideally extend to at least 5 years, which is beyond the 3-year project duration common in marine science.

Characterising the fate of nitrogenous waste from the sea-cage aquaculture of spiny lobsters using numerical modelling.

Although the aquaculture of spiny lobsters has been expanding since the 1970s, very little is known about the potential environmental impacts on water quality of this activity. This study quantified the production of dissolved inorganic nitrogen (DIN) from Australasian red spiny lobsters, Jasus edwardsii, in the laboratory, and these data were then used in a numerical model to predict the dispersal pattern of DIN from a hypothetical commercial spiny lobster farm for a coastal site where such a farm would typically be located. Modelling scenarios were set up with combinations of two different stocking densities (3 and 5 kg m(-3)), two different diets (mussels and moist artificial diet) and three different feed conversion ratios (FCR = 3, 5 and 28). DIN excretion rate from unfed lobsters in the laboratory on average was 1.10 ± 0.12 μg N g(-1) h(-1) while feeding lobsters on mussels and artificial diet increased DIN excretion significantly by around eightfold and twofold, respectively. Ammonia was consistently the dominant contributor to measured DIN output from lobsters. Modelling results indicated that the mean elevated DIN from a hypothetical farm where the lobsters were fed with mussels ranged from 7 up to 20 μg N L(-1) with increasing stocking density and FCR and was 30-150 % higher than the mean elevated DIN resulting from lobsters fed with artificial diet. Overall, the results indicated that DIN output from the hypothetical spiny lobster sea-cage farming is unlikely to be problematic using the FCR, stocking density, and the number of cages modelled at the coastal site in this study. Furthermore, feeding lobsters with artificial diet can help maintain a lower DIN output than seafood, such as mussels or trash fish.