Relationship between the Physicochemical Properties of Nonchitinolytic Listeria and Salmonella and Their Attachment to Shrimp Carapace

Listeria and Salmonella are important foodborne pathogens normally associated with the shrimp production chain. This study investigated the potential of Salmonella Typhimurium, Salmonella Senftenberg, and Listeria monocytogenes (Scott A and V7) to attach to and colonize shrimp carapace. Attachment and colonization of Listeria and Salmonella were demonstrated. Shrimp abdominal carapaces showed higher levels of bacterial attachment (P < 0.05) than did head carapaces. Listeria consistently exhibited greater attachment (P < 0.05) than did Salmonella on all surfaces. Chitinase activity of all strains was tested and found not to occur at the three temperatures (10, 25. and 37 degrees C) tested. The surface physicochemical properties of bacterial cells and shrimp carapace were Studied to determine their role in attachment and colonization. Salmonella had significantly (P < 0.05) more positive (-3.9 and -6.0 mV) cell surface charge than Listeria (-18 and -22.8 mV) had. Both bacterial species were found to be hydrophilic (<35%) when measured by the bacterial adherence to hydrocarbon method and by contact angle (theta) measurements (Listeria, 21.3 and 24.8 degrees, and Salmonella, 14.5 and 18.9 degrees). The percentage of cells retained by Pheryl-Sepharose was lower for Salmonella (12.8 to 14.8%) than it was for Listeria (26.5 to 31.4%). The shrimp carapace was found to be hydrophobic (theta = 74.5 degrees), and a significant (P < 0.05) difference in surface roughness between carapace types was noted. There was a linear correlation between bacterial cell Surface charge (r(2) = 0.95) and hydrophobicity (r(2) = 0.85) and initial attachment (P < 0.05) of Listeria and Salmonella to carapaces. However, the same properties Could not be related to subsequent colonization.

Temporal and Spatial Patterns in Recruitment of Three Penaeid Prawns in Moreton Bay, Queensland, Australia

The size at recruitment, temporal and spatial distribution, and abiotic factors influencing abundance of three commercially important species of penaeid prawns in the sublittoral trawl grounds of Moreton Bay (Queensland, Australia) were compared. Metapenaeus bennettae and Penaeus plebejus recruit to the trawl grounds at sizes which are relatively small (14-15 mm carapace length, CL) and below that at which prawns are selected for, and retained, in the fleet's cod-ends. In contrast, Penaeus esculenlus recruit at the relatively large size of 27 mm CL from February to May, well above the size ranges selected for. Recruitment of M. bennettae extends over several months, September-October and February March, and was thus likely to be bi-annual, while the recruitment period of P. plebejus was distinct, peaking in October-November each year. Size classes of M . bennettae were the most spatially stratified of the three species. Catch rates of recruits were negatively correlated with depth for all three species, and were also negatively correlated with salinity for M. bennettae.

Distribution of barnacle epizoites of the crab Portunus pelagicus in the Moreton Bay region, eastern Australia

The parasites of some decapod crustaceans are known to cause sterilisation of their hosts, and can thus have an important impact on the population dynamics of infested species. Blue swimmer crabs (Portunus pelagicus) collected in three areas around Moreton Bay, Australia were examined for the presence of epizoic barnacles in their branchial chambers and on their carapace. Of the 952 crabs inspected 92% were infested with Octolasmis spp. The mean number of barnacles (predominantly Octolasmis warwickii) per carapace and gill chamber (mainly O. angulata) were 2.35 and 71.1, respectively. Barnacle infestation of gills was found to differ significantly by area, season and sex with the deeper offshore areas exhibiting the highest number of barnacles. The distribution within the hosts showed barnacles were more likely to be distributed in areas closer to the inhalant aperture. Highest abundances were found on the proximal surface of the hypobranchial side of gills 3, 4 and 5. Host moult stage and parasitism by Sacculina granifera were also found to affect the abundance of epizoic barnacles in some areas.

The effects of holding space on growth and survival of individually reared three-spot crab (Portunus sanguinolentus).

The problem of cannibalism in communally reared crabs can be eliminated by separating the growing crabs into holding compartments. There is currently no information on optimal compartment size for growing crabs individually. 136 second instar crablets (Portunus sanguinolentus) (C2 ca. 7-10 mm carapace width (CW)) were grown for 90 days in 10 different-sized opaque and transparent walled acrylic compartments. The base area for each compartment ranged from small (32 mm × 32 mm) to large (176 mm × 176 mm). Effects of holding space and wall transparency on survival, CW, moult increment, intermoult period and average weekly gain (AWG) were examined. Most crabs reached instars C9-C10 (50-70 mm CW) by the end of experiment. The final survival rate in the smallest compartment was 25% mainly due to moult-related mortality predominantly occurring at the C9 instar. However, crabs in these smaller compartments had earlier produced significantly larger moult increments from instar to instar than those in the larger compartments (P < 0.05). Crabs in the smaller compartments (<65 mm × 65 mm) also showed significantly longer moult periods (P < 0.05). The net result was that AWG in CW was 5.22 mm week-1 for the largest compartment and 5.15 mm week-1 in smallest and did not differ significantly between compartment size groups (P = 0.916). Wall transparency had no impact on survival (P = 0.530) but a slight impact on AWG (P = 0.014). Survival rate was the best indicator of minimum acceptable compartment size (?43 mm × 43 mm) for C10 crablets because below this size death occurred before growth rate was significantly affected. For further growth, it would be necessary to transfer the crablets to larger compartments.

Limb-loss in pond-reared blue swimmer crabs Portunus pelagicus (L.): Effect on growth in an indoor shedding system

Limb-loss in crustaceans can reduce moult increment and delay or advance the timing of moulting, both aspects that are likely to impact upon soft-shell crab production. Pond-reared blue swimmer crabs Portunus pelagicus were harvested and maintained in a crab shedding system. The wet weight, carapace width (CW) and the occurrence of limb-loss were assessed before stocking in the shedding system and after each of the next three moults. Many of the crabs were initially missing one or two limbs and these did not grow as much as the crabs that were intact at the start of the trial. Despite its strong correlation with wet weight, CW changes proved to be misleading. Limb-loss reduced the %CW increment but not the per cent weight increment (where the later is calculated from the actual pre-moult weight). Pre-moult weight explained much of the variation in post-moult weight, with crabs moulting to approximately double their weight. Limb-loss reduced 'growth' and production from the pond because it reduced pre-moult weight but limb-loss did not alter the weight change on shedding a given weight of crabs, although some of that change now included regeneration of limbs. One can hypothesize that much of the size variation seen in pond-reared crabs may be due to accumulated effects of repeated limb-loss, rather than genetic variation.

Raw data for project "Development of a DNA based aging technique for use in fisheries assessments" Fisheries and Development Corporation project 2007/033

The primary aim of this study was to determine the relationship between telomere length and age in a range of marine invertebrates including abalone (Haliotis spp) oysters (Saccostrea glomerata), spiny lobsters (Sagmariasus verreauxi formerly Jasus verreauxi and Jasus edwardsii) and school prawns (Metapenaeus macleayi). Additionally, this relationship was studied in a vertebrate organism using the freshwater fish Silver perch (Bidyanus bidyanus). Telomere length differences between tissues were also examined in some species such as Saccostrea glomerata, Sagmariasus verreauxi and Bidyanus bidyanus. In some cases cultured specimens of known age were used and this is quoted in the spreadsheets. For other wild-caught specimens where age was not known, size was used as a proxy for age. This may be a broad size class, or be determined by shell size or carapace length depending on the organism. Each spreadsheet contains raw data of telomere length estimates from Terminal Restriction Fragment Assays (TRF) for various individuals of each species including appropriate details such as age or size and tissue. Telomere length estimates are given in base pairs (bp). In most cases replicate experiments were conducted on groups of samples three times but on a small number of occasions only two replicate experiments were conducted. Further description of the samples can be found in final report of FRDC 2007/033. The arithmetic average for each individual (sample ID) across the two or three replicate experiments is also given. Bidyanus bidyanus (SilverPerch) Two sheets are contained within. a) Comparison of telomere length between different tissues (heart, liver and muscle) within the three year old age class - two replicate experiments were conducted. b) Comparison of telomere length between fish of different but known ages (0.25, 1, 2, and 3 years old) in each of three tissues, heart, liver and muscle – three replicate experiments were conducted per tissue. Haliotis spp (Abalone species) Three species were tested. H. asinina Telomere length was compared in two age classes-11 month and 18 month old abalone using muscle tissue from the foot. Within gel-variation was also estimated using a single sample run three times on one gel (replicate experiment). H. laevigata x H. rubra hybrids Telomere length was compared in three known age classes – two, three and four years old using muscle tissue from the foot. H. rubra Telomere length was compared in a range of different sized abalone using muscle tissue from the foot. Shell size is also given for each abalone Saccostrea glomerata Three sheets are contained within the file. a) Samples came from Moreton Bay Queensland in 2007. Telomere length was compared in two tissues (gill and mantle) of oysters in three age groups (1, 3 and 4 years) b) Samples came from Moreton Bay Queensland in 2009. Telomere length was compared in three age classes using DNA from gill tissue only c) Samples came from Wallis Lake, New South Wales. Telomere length was estimated from whole body minus the shell from 1 year old oysters, gill tissue of 3 age classes (1.5 years, 3 and 4 years), mantle tissue of two age classes (3 and 4 years). Sagmariasus verreauxi (formerly Jasus verreauxi) Telomere length was estimated from abdomen tissue of puerulus, gill and muscle tissue of 3 year old, large and very large size classes of lobsters. Jasus edwardsii Telomere length was measured in two size classes of lobsters- adults of varying sizes using muscle tissue and puerulus using tissues from the abdomen minus the exoskeleton. Metapenaeus macleayi Telomere length was measured in three size classes of school prawns adults. Muscle tissue was used, minus the exoskeleton.

Giant mud crab (Scylla serrata): Relative efficiencies of common baited traps and impacts on discards

This study was initiated in response to a scarcity of data on the efficiency, selectivity and discard mortality of baited traps to target Scylla serrata. Five replicates of four traps, including "hoop nets", rigid "wire pots", and collapsible "round" and "rectangular" pots were deployed for 3, 6 and 24 h in two Australian estuaries. Trapped S. serrata were "discarded" into cages and monitored with controls over 3 d. All S. serrata were assessed for damage, while subsets of immediately caught and monitored individuals had haemolymph constituents quantified as stress indices. All traps retained similar-sized (8.119.1 cm carapace width) S. serrata, with catches positively correlated to deployment duration. Round pots were the most efficient for S. serrata and fishmostly Acanthopagrus australis (3 mortality). Hoop nets were the least efficient and were often damaged. No S. serrata died, but 18 were wounded (biased towards hoop nets), typically involving a missing swimmeret. Physiological responses were mild and mostly affected by biological factors. The results validate discarding unwanted S. serrata for controlling exploitation, but larger mesh sizes or escape vents in pots and restrictions on hoop nets would minimise unnecessary catches, pollution and ghost fishing. © 2012 International Council for the Exploration of the Sea. Published by Oxford University Press. All rights reserved.

Damage and physiological stress to juvenile eastern rock lobster (Sagmariasus verreauxi) discarded after trapping and hand collection

Large numbers of Sagmariasus verreauxi are trapped and hand collected in Australia, but discarded due to size and quota restrictions, and under the unevaluated assumption of few impacts. To test the validity of enforced discarding, trapped and hand-collected S. verreauxi (49-143. mm carapace length - CL) were examined for external damage, placed into cages, transferred to aquaria and monitored (with controls) over three months. Haemolymph was non-repetitively sampled immediately and at one, three, and seven days to quantify stress. Most trapped (64%) and hand-collected (79%) specimens were undersized (<104. mm CL), with the latter method yielding broader ranges of sizes and moult stages. Within-trap Octopus tetricus predation caused the only mortalities (3.3%). Hand collection resulted in much greater antennae and pereopod loss than trapping (53 vs. 4%) but, compared to controls, both methods evoked benign physiological responses that resolved within a week. While most wounded S. verreauxi regenerated all or some missing appendages post-moult, their mean CLs were less than those from intact conspecifics. Simple strategies, including larger mesh sizes, and/or installing modifications to reduce bycatch in traps, careful hand collection, and appropriate release techniques might minimise impacts (including predation) to unwanted S. verreauxi, and help to control stock exploitation. © 2012 Elsevier B.V.

Long-term variation of tropical rock lobster panulirus ornatus (decapoda, palinuridae) growth inTorres Strait, Australia

This analysis of all carapace length measurements collected between 1989 and 2009, during scientific surveys, describes the variation of tropical rock lobster, Panulirus ornatus, somatic growth in Torres Strait. Multiple models of carapace length frequency distributions were compared by maximum likelihood to determine which hypotheses were most supported by the data. The best model assumed sex and cohort-specific Von Bertalanffy's parameters. These estimates are consistent with results derived from tagging data collected in the 1980s and provide new information on parameters' uncertainty. In the past two decades, growth rates have fluctuated inter-annually without displaying any distinctive trend. Associated uncertainties are large, suggesting that sampling will need to be intensified in order to detect an effect of climate change.

Performance and physiological responses of combined t-bar and PIT tagged giant mud crabs (Scylla serrata)

Mud crabs (Scylla spp.) are intensively caught throughout South-East Asia and support a very substantial commercial, recreational fishing and aquaculture industry. Identification of individual animals is important to improve understanding and management of this species. However, tagging of crustaceans is difficult as they frequently molt and internal tags can pose a hazard to consumers. In this pilot study we tested a new method combining passive integrated transponder tags and t-bar tags externally. 45 giant mud crabs (Scylla serrata) were captured from the wild and kept in tanks for a maximum of 10 months. We inserted tags into the abdomen of 35 giant mud crabs and tested a modified method where the combined t-bar/PIT-tag was inserted into the muscle tissue of the rear leg between the dorsal carapace plate and the top of the abdominal flap. Tagged crabs with the modified method showed 85% tag retention for molting crabs. We tested the same method in the field where 852 individuals were tagged with combined t-bar/PIT-tags of which 82 were recaptured showing 100% tag retention but without any evidence of molting having occurred. The tested method of combined t-bar/PIT-tags in giant mud crabs can further improve monitoring for wild and aquaculture populations and can be deployed widely with low cost.

Performance and physiological responses of combined t-bar and PIT tagged giant mud crabs (Scylla serrata)

Mud crabs (Scylla spp.) are intensively caught throughout South-East Asia and support a very substantial commercial, recreational fishing and aquaculture industry. Identification of individual animals is important to improve understanding and management of this species. However, tagging of crustaceans is difficult as they frequently molt and internal tags can pose a hazard to consumers. In this pilot study we tested a new method combining passive integrated transponder tags and t-bar tags externally. 45 giant mud crabs (Scylla serrata) were captured from the wild and kept in tanks for a maximum of 10 months. We inserted tags into the abdomen of 35 giant mud crabs and tested a modified method where the combined t-bar/PIT-tag was inserted into the muscle tissue of the rear leg between the dorsal carapace plate and the top of the abdominal flap. Tagged crabs with the modified method showed 85% tag retention for molting crabs. We tested the same method in the field where 852 individuals were tagged with combined t-bar/PIT-tags of which 82 were recaptured showing 100% tag retention but without any evidence of molting having occurred. The tested method of combined t-bar/PIT-tags in giant mud crabs can further improve monitoring for wild and aquaculture populations and can be deployed widely with low cost.