Optimal feed pellet size for culturing juvenile spiny lobster Jasus edwardsii (Hutton, 1875) in New Zealand

There is intense international interest in the development of spiny lobster aquaculture and of particular interest is the development of artificial diets for spiny lobsters. However, there is little information on the feeding behaviour of spiny lobsters and their ability to handle and consume artificial feeds of different dimensions. Observations of the feeding behaviour of juveniles of the spiny lobster Jasus edwardsii in culture found that they waste significant amounts of food through externally fragmenting the feed pellets before sweeping particles into the mouth. The consumption efficiency of different sized pellets was found to change markedly with increasing size of the juvenile lobsters. Up to 50% of artificial food was wasted by the inefficient feeding behaviour of the lobsters. However, consumption of the feed could be reduced by as much as 19% by altering pellet size. These results indicate that the size of feed pellets, and their consistency and fragmentation characteristics, will be critical aspects of cost‐effective feeding of cultured spiny lobsters.     

Effects of dietary carbohydrate on growth of juvenile New Zealand rock lobsters, Jasus edwardsii

The commercial aquaculture of spiny lobsters is impeded by the development of effective practical diets, which is partly due to a lack of knowledge of the digestive capabilities and nutritional needs of these species. Carbohydrates have the potential to provide a low cost energy source in practical diets for spiny lobsters. This research investigated the effect of algal carbohydrates, on the growth of juvenile rock lobsters. Juvenile lobsters, Jasus edwardsii, (10-12 mm carapace length) were provided with one of five diets; blue mussel, squid (Nototodarus gouldii), or a mussel diet partially substituted with algal carbohydrates, either agar, carrageenan or alginate over 80 days in culture. In all treatments, diet consumption and lobster growth were maintained or increased over time. Growth was highest for the mussel diet followed by the agar diet. Similar lobster growth occurred on the carrageenan and alginate diets, with the least on the squid diet. After 80 d there were significant differences in the percent lipid and glycogen stored in the mid-gut gland with highest levels of glycogen in lobsters fed the mussel only diet. Percent protein in the tail muscle was greatest for mussel fed lobsters. The mid-gut index (mid-gut weight/whole wet weight) was highest for the mussel only diet and this was similar to control lobsters at the start of the experiment. The results indicate that glycogen from mussels and agar could be used as carbohydrate source in the future development of a practical diet for spiny lobsters.     

Assessment of the production and dispersal of faecal waste from the sea‐cage aquaculture of spiny lobsters

Despite the rapid expansion of spiny lobster aquaculture, very little is known about its potential environmental impacts. In an effort to understand the potential impacts of sea‐cage culture of spiny lobsters, the faecal output and settling velocity of faeces of spiny lobster were quantified. These data were then used in hydrodynamic modelling to assess the dispersal pattern of faecal material from two sizes of hypothetical spiny lobster farms, so that inferences about likely benthic impacts could be made by modelling different scenarios of farm stocking density and food conversion efficiency. The overall mean settling velocity of lobster faecal strands was 0.9 ± 0.05 cm s^?1. There was a positive correlation between both the weight and density of faecal strands and their settling velocity. Conversely, neither the length nor the surface area of faecal strands was correlated with the settling velocity. Hydrodynamic modelling showed that faecal material deposition mainly occurred directly beneath the sea‐cages. The density of faecal material deposition increased proportionately with higher stocking density and FCR values. Overall, the results indicate that the deposition of faecal waste from sea‐cage lobster aquaculture is unlikely to cause widespread benthic impacts when operating to the current highest commercial stocking and feeding levels.     

Commercial land-based farming of European lobster (Homarus gammarus L.) in recirculating aquaculture system (RAS) using a single cage approach

In the past, farming of the European lobster in land-based systems has turned out to be difficult. The ideal system for rearing lobsters individually should be relatively inexpensive to construct and operate, simple to maintain, based on automatic feeding and self-cleaning of tank and cages, maintain ideal water quality conditions, use space in three dimensions, enable high densities, conserve water at high temperatures, ensure good survival and permit easy access to the livestock for inspection and feeding. Several attempts have been made to mass-produce these cannibalistic crustaceans under controlled environments. However, none of the many previous attempts have proved to be successful in incorporating all of these features into a single design. Thus, the development of land-based lobster farming has been severely hampered by lack of suitable technology and production methods. The major constraints have been the need for individual rearing cages to avoid cannibalism, need of heated water, lack of high quality dry food, high labor costs, inadequate technological solutions and high investment costs.Today, Norwegian Lobster Farm operates the world's first land-based RAS farm producing plate sized lobsters. The company also operates its own brood-stock department and a hatchery for production of IV-stage juveniles. The system contains a patented single cage technology with moving bed biofilters where the recirculation system is designed to fit the water management. Automated solutions for accurate feeding, robots supporting mass-rearing of the IV-stage juveniles and image processing programs for daily monitoring of each single individual have been developed and successfully tested.     

An evaluation of potential diets for the culture of postpueruli spiny lobsters Panulirus argus (Palinuridae)

Provision of a suitable feed is paramount for the ongoing success of spiny lobster culture. This study compared and evaluated the performance of seven diets for first instar juvenile spiny lobster Panulirus argus [5–6 mm carapace length (CL)] based on growth rates, survival, and feed conversion ratio. Results demonstrated that a seafood-based juvenile formulation produced the fastest growth rate (3.49% weight gain day⁻¹ and 0.90% CL increase day⁻¹ over a 28-day period). These growth rates were also reflected by a low feed conversion rate (3.04) for this formulated feed. Similar results were also obtained for juveniles fed a frozen seafood diet, however, frozen brine shrimp, Artemia salina (both enriched and un-enriched), frozen enriched mysis shrimp, a dry pellet, and a meal-based juvenile formulation did not produce consistent growth rates. Survival rates ranged between 38% and 85% and demonstrate that juvenile lobsters have better likelihoods of survival in captive culture environments compared to the wild. Although further nutritional refinement is recommended, the results from this research have significant implication for the possible expansion of juvenile spiny lobster growout to a larger scale.     

Efficacy of a starch-iodide swab technique to detect the illegal use of bleach in a Spiny Lobster (Panulirus argus) fishery

The destructive and illegal practice of using chemicals (bleach, dishwashing liquid, gasoline) to catch spiny lobster (Panulirus argus) is thought to be common throughout much of the Bahamian Archipelago. Injection of a chemical irritant into a lobster den will result in either a rapid escape response or a subduing effect, both of which make it easier to capture spiny lobster. We used both laboratory and field trials to determine the efficacy of a starch-iodide swab technique to identify lobsters that had been exposed to bleach solution (NaOCl). All lobsters exposed to bleach tested positive immediately following exposure and for varying periods thereafter. No false positives were detected on control lobsters. The average length of time that bleach remained detectable on the exoskeleton was 6.2 and 9.6 h in the laboratory and field, respectively, with some individuals testing positive 12 h after exposure. The swab technique will provide fishery officers with a powerful tool to reduce or eliminate the illegal use of bleach for harvesting spiny lobster.     

Bioeconomic Analysis of Improved Diets for Lobster,Panulirus ornatus,Culture in Vietnam

Culture‐based growout of tropical spiny lobster, Panulirus ornatus, is a nascent and unique industry that faces a number of challenges and opportunities. Of particular interest to this study is the imminent development of pelleted diets for lobster (probably within 3 yr) that will potentially reduce the industry's dependence on bycatch for feed (with benefits to wild stocks of fish and reduced downstream environmental impacts). The aim of this paper is to conduct a bioeconomic analysis of lobster growout farming in Vietnam and analyze the cost‐effectiveness of potential manufactured feed diets for these farms. Growout lobster farming is found to be a high‐cost and high‐return industry, with a benefit cost ratio of approximately 1.44. Approximately 60% of the total costs are feed related, with the quantity of feed being the production parameter with the highest variability. Hence, reducing the cost and increasing the efficiency of feeding will have a significant impact on the level and variability of profit. It is expected that manufactured diets will improve the profitability by approximately 267 million VND/yr for an individual farmer (15,000 USD) and approximately 435 billion VND/yr for the industry (24 million USD). This is expected to double again if the diets have the added benefit of reducing mortality through the inclusion of vitamins and other additives.     

A two-chambered trap reduces within-trap predation by octopus on rock lobsters in aquarium trials

A two-chambered lobster trap was developed that in aquarium trials significantly (p < 0.01) reduced octopus predation on trap-caught spiny lobster. The trap was designed using information gained from an investigation of the behavioural interactions of the maori octopus (Octopus maorum) with traps used in the South Australian commercial lobster (Jasus edwardsii) fishery. This study showed that octopuses were primarily attracted to traps by the presence of bait as opposed to lobsters and that octopus entry into traps was ‘fortuitous’ and mediated by speculative exploration. The outer chamber of the modified trap contained bait and allowed entry by octopuses but not lobster and the inner chamber allowed access to both animals. The trap worked on the principle that octopuses would enter the outer chamber containing bait via a side entrance in preference to entry to the inner chamber containing lobsters via the neck. This was found to be the case and lobster mortality was 70% lower in the two-chambered trap than a standard trap. Successful adaptation of this trap design to commercial fishing conditions could significantly reduce rates of octopus predation on rock lobsters in several important southern hemisphere fisheries for spiny lobsters.     

Safety issues and sustainable development of European aquaculture: new tools for environmentally sound aquaculture

Sustainable and long-term growth of the aquaculture industry should involve both ecologically sound practices and appropriate resource management. The increasing economic dimension of Mediterranean aquaculture is opening new economic niches and may be a valid support to reduce the pressure of traditional fisheries. Aquaculture practices can also lead to modifications of coastal habitats through the impact of wastes of land-based and open-sea mariculture facilities. In addition to these aspects which place a direct pressure on aquatic ecosystems and wild fishery resources, a wide range of environmental contaminants, such as chemicals used in farming operations, can accumulate in farmed organisms and put fish health and quality at risk. Thus, as aquaculture makes its transition to a major food-producing sector, proper assessment and control of environmental impacts and food safety awareness are becoming increasingly important. The development of simple tools able to monitor the extent of environmental and biological impacts associated with farming operations at various levels of biological complexity from the ecosystem to the organism level is required. Although a number of techniques for assessing the environmental and biological impact of pollutants in natural ecosystems are available, the development of practical and validated tools is sorely needed in aquaculture.     

Temperature and Salinity Tolerances of the Tropical Spiny Lobster,Panulirus ornatus

Interest in the development of aquaculture of the tropical spiny lobster, Panulirus ornatus, has increased markedly over the past 10 yr because of strong market demand and high prices. In Australia, economic conditions will necessitate that a semi‐intensive approach be taken, possibly involving managed environmental conditions. Identification of optimal temperature and salinity levels will be necessary, and therefore two experiments were performed to examine these two parameters. Juvenile lobsters were grown in tanks at five temperatures (19, 22, 25, 28 and 31 C). Growth was significantly affected by temperature (P < 0.01), and maximal growth occurred at 25–31 C. Examination of the temperature effect on molt increment and intermolt period indicated that 27 C was the optimal temperature, at which molt increment was greatest and intermolt period the least. Temperature also had a significant (P < 0.01) positive effect on apparent feed intake (AFI). Juvenile lobsters were also exposed to four different salinities (20, 25, 30 and 35 ppt) over a period of 91 d. Significant differences (P < 0.01) were apparent for both survival and growth. Lowest survival occurred at 35 ppt which may be attributable to higher cannibalism at that salinity. Growth was highest at 35 ppt and progressively less at lower salinities. Although full marine salinity (35 ppt) will generate best performance of P. ornatus, its capacity to tolerate reduced salinity will provide greater opportunity to develop commercial aquaculture.     

Tropical spiny lobster (Panulirus ornatus) farming in Vietnam – bioeconomics and perceived constraints to development

This paper presents bioeconomic data on lobster farming in Vietnam, and perceived constraints to the development of the industry. The farms were found to be profitable, with an average benefit cost ratio of 1.44 and an average net revenue of 262 million VND year^?1 (or just under US$15 000 year^?1). Investment in the enterprise is high compared with other enterprises in the region. However, disease has the potential to devastate lobster crops and there is little information available to lobster farmers about disease prevention and management. Hence, the lobster enterprise is a high‐risk high‐return industry. The predominant perceived constraints to the development of lobster operations include water quality and temperature issues, insufficient access to credit, good‐quality affordable feed and accurate information about technology improvements in lobster farming. It seems that improving the livelihood of lobster farmers in Vietnam is dependent on reducing their dependence on wild stocks for seed and feed, improving access to credit and improving technical and market information flows. Such improvements are likely to lead to higher profitability, given high export demand and hence sustained high prices for their lobster product.     

Economic analysis of land based farming of salmon

Abstract

Land-based farming of salmon is emerging for a number of reasons. The demand for salmon is increasing in many parts of the world. In recent years there has been limited growth in production due to binding government regulations and environmental challenges in sea-based salmon aquaculture. This is true both for Norway (sea lice, salmon escapes) and Chile (sea lice, disease problems), the two largest producers of salmon. Growing demand and limited expansion in production have made for a very profitable industry. At the same time, there have been technological developments when it comes to land-based farming (a technology used for smolt production and species such as sole and turbot), and cost of production has changed. Currently, land-based salmon farming is in operation or in development in several countries including the USA, Denmark, and Norway. In this paper, the economics of land-based salmon farming in a Norwegian context is presented, with an emphasis on the relative competitiveness of this vis-à-vis sea-based farming. If successful, land-based farming could potentially have an important impact on the dynamics of the salmon market.     

Feeding and gut evacuation of cultured juvenile spiny lobsters, Jasus edwardsii

Low feed consumption has been suggested as a major impediment for the development of effective formulated diets for spiny lobsters. To seek an explanation for the low feed consumption, this study compared the feed consumption, appetite revival, foregut evacuation and fecal production of different sizes of spiny lobster Jasus edwardsii juveniles fed a fresh natural diet (i.e. mussel flesh) and a dry formulated diet. In addition, the effect of feeding frequency was determined by feeding juvenile lobsters the same ration of formulated diet at different time intervals. i.e., same ration delivered 3 week^− 1, 1 day^− 1, 2 day^− 1, 5 day^− 1 and 5 night^− 1. Lobster (10–15 g) growth and feed consumption (1.15% BW day^− 1) was maximized when receiving a single ration daily of the formulated diet. A slow appetite revival (AR > 18 h) on the formulated diet was consistent with the negative effect of increasing feeding frequency on growth and consumption. In addition, there appeared to be no major advantage in dry matter intake by providing the nutrient dense dry formulated diet to Jasus edwardsii. Lobsters fed fresh mussel flesh (79.8% moisture) consumed similar levels of dry matter as those lobsters fed the dry formulated feed (7.3% moisture). This appears to be due to high moisture gain and expansion of the dry feed in the lobster foregut. Foregut evacuation lasted 10 h for the two diets but a delay in initial foregut evacuation and processing of the formulated diet was evident, and may have negatively affected feed consumption, appetite revival and dry matter digestibility (61.2%) of the dry formulated diet compared to the mussel flesh diet (89.2%). Appetite revival on mussel flesh was almost complete by 12 h after a satiation ration and was governed primarily by the rate of foregut evacuation. Differences in the timing of foregut evacuation and fecal production between the two diets suggested that a greater proportion of the formulated diet entered the midgut directly.The results indicate that J. edwardsii cannot achieve high levels of feed consumption on formulated diets because gut throughput is reduced due to a small foregut capacity, expansion of the feed post-ingestion, lengthy foregut filling time (1–2 h) and clearance time (10 h), combined with slow gut throughput time (34–42 h) and appetite revival (> 18 h). A slow appetite revival and difficulties in processing and digestion of formulated diets appear as major issues to be resolved to improve the performance of formulated diets required for the commercial aquaculture of J. edwardsii and possibly other spiny lobsters.     

The Achilles heel for spiny lobsters: the energetics of the non‐feeding post‐larval stage

Spiny lobsters are highly valuable seafood species that are captured and marketed in more than 90 countries. After more than 30 years of stable catches, spiny lobster fisheries in many parts of the world are declining due to decreased recruitment. The planktonic larvae spend up to 2 years in offshore waters, accumulating energy stores to fuel the non‐feeding post‐larva, or puerulus, to actively migrate onshore and settle. The total energy required by spiny lobster pueruli for cross‐shelf migration has not been accurately determined. Recent advances in larval culture have provided the opportunity for the first detailed examination of the swimming performance, respiratory metabolism and nitrogen excretion of spiny lobster (Sagmariasus verreauxi) throughout the puerulus stage. The routine and active metabolic rates of pueruli were lower than for most other decapod larvae, probably to provide greater energy efficiency. However, pueruli were found to have limited time, swimming ability and fuel for active cross‐shelf migration. It is estimated that S. verreauxi pueruli require at least 13.8 mg of stored lipid to provide sufficient energy (18.4% DW) to complete the puerulus stage and recruit to coastal habitats. The ability of the preceding phyllosoma larvae to accumulate these reserves, and the presence of favourable oceanographic conditions during the limited time available to the migrating puerulus, are both crucial to subsequent successful recruitment. Spiny lobster recruitment processes appear to be particularly vulnerable to changes in oceanic climate which is likely to contribute to the recent large‐scale declines in recruitment to valuable fished populations.     

Effects of marine reserve protection on spiny lobster (Jasus edwardsii) abundance and size at Tonga Island Marine Reserve,New Zealand

• 1. Diving surveys were undertaken to investigate the effects of marine reserve protection on spiny lobster (Jasus edwardsii) populations at Tonga Island Marine Reserve, northern South Island, New Zealand over a 2 year period from December 1998 to December 2000.
• 2. Spiny lobsters were 2.8 times more abundant overall, and mean size was 19 mm carapace length larger in shallow transects and 28 mm carapace length larger in deep transects, in the marine reserve than at adjacent fished sites. That pattern was evident despite very high variability within sites, and among sites within reserve and fished areas.
• 3. Large reproductive males were 10 times more abundant within the reserve compared to adjacent fished areas, suggesting that more eggs would be fertilized in the reserve than on the adjacent fished coast.
• 4. Estimates of size‐specific fecundity, combined with abundances of females, suggested that almost nine times more eggs would be produced in the reserve than in fished areas.
• 6. We estimate that the mean abundance of spiny lobster in the reserve has increased by 22%, 5 years after its establishment, indicating an annual population increase of 4.4%. Over the same period, abundance of spiny lobster outside the reserve has declined by 2.9% per annum.
• 7. Based on known spiny lobster movements, we suggest that marine reserves of more than 10 km length should be given priority over smaller reserves. Smaller reserves will, however, protect part of the population for at least a portion of their lifespan.
• 8. Previous studies of movement of J. edwardsii suggest that spillover from the reserve should occur, and as population density increases we predict that more spiny lobsters will move out from the reserve.

Copyright © 2002 John Wiley & Sons, Ltd.     

Culture of juvenile European lobster (<Emphasis Type="Italic">Homarus gammarus</Emphasis> L.) in submerged cages

A bottleneck for re-establishment or enhancement of lobster (Homarus gammarus L.) populations through release of hatchery-produced juveniles is ineffective and expensive juvenile production. In this study, we cultured lobster juveniles from stage V to a size being suitable for re-establishment or enhancement purposes (40–50 mm total length) in cages submerged under existing facilities for culture of bivalves. The lobsters were not feed or tended during the culture period (6–14 months). The survival and growth rates were similar or higher compared to what has been achieved with other methods used for culture of lobster juveniles in the past. The highest survival (82–89%) and fastest growth (4–5 cm total length over 190–250 days) were achieved using commercial oyster baskets. It is believed that the juveniles fed on naturally occurring plankton and organisms growing inside the cages. Thus, the current study shows that it is possible to culture lobster juveniles for reestablishment or enhancement purposes in a way that would involve less investments and operational costs than earlier used methods as there would be no need for artificial heating of water, for large buildings or for continuous feeding and tending of large numbers of juveniles.     

Commercial marine fish farming in Singapore

Commercial marine fish farming in Singapore is mainly the culture of economically important foodfish species in floating cage nets. There are 84 licensed fish farms occupying 46.5 hectares (ha) of coastal waters. Production from these farms accounts for the bulk of aquaculture production in Singapore, being 3554 tonnes (‘metric tons’, t) in 1995, or 98% of total production of 3625t. The commonly cultured species are the green mussels, Perna viridis L., which form the bulk of production (70.4%), finfish like the groupers, Epinephelus tauvina Forsskal and E. malabaricus Schneider, Asian sea bass, Lates cakarifer Bloch, and snappers, Lutjanus johni Bloch and L. argentimaculatus Forsskal, and crustaceans like the mangrove crab, Scylla serrata Forsskal and spiny lobster, Panilurus polyphagus Herbst. The basic farm structure for fish and mussel culture is the floating wooden raft. In finfish farming, polyethylene cage nets are attached to the raft in which popular foodfishes are cultured. The mussel raft is a structure to which polyethylene ropes are attached to collect and grow out green mussels from natural spatfall. Fish seeds for farming are mostly wild-caught. Only the Asian sea bass and the banana shrimp (Penaeus merguiensis de Mann) are produced by commercial hatcheries in Singapore and the region. The fry of pompano (Trachinotus blochii Lacepede, and T. falcatus Klausewitz & Nielsen) are imported from Taiwan. Trash fish is still the main feed used for the farming of finfish and crustaceans like the mangrove crab and lobster because it is cheap and readily available. This paper also reviews the economics of commercial finfish and mussel farming in Singapore today.     

Acute toxicity of emamectin benzoate (SLICE™) in fish feed to American lobster, Homarus americanus

SLICE? (active ingredient 0.2% emamectin benzoate (EMB)), a feed premix developed by Schering‐Plough Animal Health for the control of sea lice on cultured salmonids, is registered for use in several countries and is being prescribed on an emergency basis in Canada and the United States. The concentration of EMB in feed administered to farmed salmon ranges from 1 to 25 μg g^?1. To determine the acute toxicity of the compound to juvenile and adult American lobster (Homarus americanus), commercial salmon feed was coated with SLICE? at a range of concentrations and provided to the animals for 7 d in the laboratory. The LC₅₀ is estimated to be 644 μg g^?1 (95% CI=428, 1275) for adult lobsters and >589 μg g^?1 for stage V and VI juvenile lobsters. The consumption of medicated pellets by adult lobsters decreased significantly with increasing concentration of EMB. Adult lobsters that died during the study had a significantly greater concentration of emamectin B1a in their muscle tissue than those that survived. These results support the conclusion that salmon feed medicated with EMB at the concentrations used by the aquaculture industry is unlikely to pose an acute lethal threat to adult and small juvenile American lobsters.     

Contribution of bait to lobster production in an oligotrophic marine ecosystem as determined using a mass balance model

The fishery for the western rock lobster (Panulirus cygnus) in Western Australia is Australia's largest trap-based fishery, deploying 8.8 million pot lifts, landing on average 11,000 tonnes of lobster and using approximately 14,000 tonnes of bait annually. A mass balance model was constructed to determine the potential contribution of this bait to the diet of western rock lobsters. Bait is potentially a significant subsidy given the oligotrophic nature of Western Australia's marine environment. The mass balance model was constructed on the principle that the biomass of the lobster population reflects the difference between inputs (growth, immigration) and outputs (natural and fishing mortality and emigration). Biomass calculated using this approach was within 7% of biomass calculated from independent estimates based on depletion analysis, indicating the model is robust. The food required to explain observed growth was then calculated, allowing the potential contribution of bait to lobster diet to be assessed. The abundance of natural diet items on the benthos was sufficient to explain the observed growth of lobsters, with bait contributing a maximum of 13% of lobster food requirements over the whole ecosystem. This contribution of bait will differ spatially and temporally reflecting uneven distribution of fishing effort and may be as high as 35% during some months of the fishing season, a result consistent with dietary studies based on stable isotopes. Given observed effects of organic matter addition on ecosystem processes as observed in trawl fisheries and aquaculture operations, it is likely that the effects of bait addition on ecosystem function are more widespread than lobster production.