Induced spawning, larval development and rearing of two indigenous Malaysian mahseer, Tor tambroides and T. douronensis

The Mahseers (Tor spp.) are highly valued freshwater fishes across the Himalayan and South-east Asian regions. Over exploitation of natural stocks because of high demand and the deteriorating environmental conditions have resulted in marked decline of mahseers in the wild. Malaysian mahseers, T. tambroides (Bleeker) and T. douronensis (Valenciennes), locally known as empurau, kelah or belian and semah, respectively, have significant cultural and economic importance but both species are now threatened in the wild because of environmental degradation and over fishing. A captive breeding programme was instigated to attempt to propagate these two species artificially for conservation and aquaculture purposes. Both pond-reared and tank-held T. tambroides and T. douronensis reached sexual maturity in captivity and were successfully induced to spawn using hormone treatments. Ovaprim (0.5 mL kg⁻¹) was the most successful hormone treatment for both species. Pre-treatment of fish with Ovaplant (28–68 μg kg⁻¹, 2–7 weeks before spawning induction) greatly improved the success rate of spawning induction. Repeat spawning (within 4 months of initial spawning) was induced in some captive fish. Use of formalin baths improved hatching by preventing fungal infections. Embryonic development and hatching are described. Juveniles were reared in static greenwater ponds. Tor tambroides reached 142–179 g (max 270 g) in 60 weeks. These results represent the first successful captive spawning and rearing of both species. Options for future research to improve production are discussed.

Foraging behaviour and habitat selection of the little penguin Eudyptula minor during early chick rearing in Bass Strait, Australia

Knowledge of the foraging areas of top marine predators and the factors influencing them is central to understanding how their populations respond to environmental variability. While there is a large body of literature documenting the association of air-breathing marine vertebrates with areas of high marine productivity, there is relatively little information for species restricted to near-shore or continental-shelf areas. Differences in foraging range and diving behaviour of the little penguin Eudyptula minor were examined from 3 breeding colonies (Rabbit Island, Kanowna Island and Phillip Island) in central northern Bass Strait, southeast Australia, during the chick-guard stage using electronic tags (platform terminal transmitters, PTTs, and time-depth recorders, TDRs). Although there were large overall differences between individuals, the mean maximum foraging range (16.9 to 19.8 km) and mean total distance travelled (41.8 to 48.0 km) were similar between the 3 colonies, despite different bathymetric environments. Individuals from all 3 colonies selected foraging habitats within a narrow sea surface temperature (SST) range (16.0 to 16.4°C). While there were significant differences in mean dive depths (5.4 to 10.9 m) and mean durations (13.2 to 28.6 s) between the different colonies, the mean diving effort (vertical distance travelled: 936.3 to 964.3 m h–1) was similar. These findings suggest little penguins from the 3 colonies employ relatively similar foraging efforts yet are plastic in their foraging behaviours.

Diet of common diving-petrels (Pelecanoides Urinatrix Urinatrix) in Southeastern Australia during chick rearing

Unlike conspecifics in the subantarctic region, which typically begin breeding in mid-spring to summer, Common Diving-petrels Pelecanoides urinatrix urinatrix in southeastern Australia (towards the northern limit of the species' distribution) commence breeding mid winter. Knowledge of the foraging ecology of this species is crucial to understanding the factors that influence its timing of breeding in the region, yet there is currently little information available. Analysis of 43 stomachs of breeding adults, collected opportunistically after they were killed in a fire which burned through their colony, indicated that their diet was dominated by two taxa: a euphausiid Nyctiphanes australis which comprised 87% of the diet by number; and a hyperiid amphipod Themisto australis which constituted a further 12.5%. Mean lengths (±SE) of N. australis (n = 39) and T. australis (n = 41) were 12 mm (±0.3) and 5.2 mm (±0.2), respectively. The importance of N. australis in the diet of Common Diving-petrels is discussed in relation to their timing of breeding and the euphausiid's potential role in the Bass Strait pelagic ecosystem.

Rearing juvenile Australian native percichthyid fish in fertilised earthen ponds

The post-larvae and fry of Australian native species, including those of species belonging to the family Percichthyidae, are routinely reared to a fingerling size (35-55 mm in length) in fertilised earthen fry rearing ponds. The juveniles of Murray cod (Maccullochella peelii peelii\ trout cod (Maccullochella macquariensis) and Macquarie perch (Macquaria australasicd) (Percichthyidae) are grown in fry rearing ponds at the Marine and Freshwater Resources Institute, Snobs Creek (Vie. Australia) for production of fingerlings for stock enhancement and aquaculture purposes. However, no detailed studies have been undertaken of the productivity of these ponds and factors that influence fish production. An ecologically based study was undertaken to increase the knowledge of pond ecology and dynamics, particularly in relation to the rearing of juvenile Murray cod, trout cod and Macquarie perch in ponds. Over nine consecutive seasons commencing in 1991, water chemistry, plankton, macrobenthos (2 seasons only) and fish were monitored and studied in five ponds located at Snobs Creek. A total of 80 pond fillings were undertaken during the study period. Additional data collected from another 24 pond fillings undertaken at Snobs Creek collected prior to this study were included in some analyses. Water chemistry parameters monitored in the ponds included, temperature, dissolved oxygen pH, ammonia, nitrite, nitrate, orthophosphate and alkalinity. Water chemistry varied spatially (within and between ponds) and temporally (diurnally, daily and seasonally). Liming of ponds increased the total alkalinity to levels that were considered to be suitable for enhancing plankton communities and fish production. Water quality within the ponds for the most part was suitable for the rearing of juvenile Murray cod, trout cod and Macquarie perch, as reflected in overall production (growth, survival and yield) from the ponds. However, at times some parameters reached levels which may have stressed fish and reduced growth and survival, in particular, low dissolved oxygen concentrations (minimum 1.18 mg/L), high temperatures (maximum 34°C), high pH (maximum 10.38) and high unionised ammonia (maximum 0.58 mg/L). Species belonging to 37 phytoplankton, 45 zooplankton and 17 chironomid taxa were identified from the ponds during the study. In addition, an extensive checklist of aquatic flora and fauna, recorded from aquaculture ponds in south-eastern Australia, was compiled. However, plankton and benthos samples were usually numerically dominated by a few species only. Rotifers (especially Filinia, Brachionus, Polyarthra, and Asplanchnd), cladocerans (Moina and Daphnid) and copepods (Mesocyclops and Boeckelld) were most abundant and common in the plankton, while chironomids (Chironomus, Polypedilum, and Prodadius) and oligochaetes were most common and abundant in the benthos. Both abundance and species composition of the plankton and macrobenthos varied spatially (within and between ponds) and temporally (diurnally, daily and seasonally). Chlorophyll a concentrations, which ranged from 1.8 to 184 \ig/L (mean 29.37 ng/L), initially peaked within two weeks of filling and fertilising the ponds. Zooplankton peaked in abundance 2-4 weeks after filling the ponds. The maximum zooplankton density recorded in the ponds was 6,621 ind./L (mean 721 ind./L). Typically, amongst the zooplankton, rotifers were first to develop high densities (2nd-3rd week after filling), followed by cladocerans (2nd-4th week after filling) then copepods (2nd-5th week after filling). Chironomid abundance on average peaked later (during the 5th week after filling). The maximum chironomid density recorded in the ponds was 27,470 ind./m2 (mean 4,379 ind./m2). Length-weight, age-weight and age-length relationships were determined for juvenile Murray cod, trout cod and Macquarie perch reared in ponds. These relationships were most similar for Murray cod and trout cod, which are more closely related phylogenetically and similar morphologically than Macquarie perch. Growth of fish was negatively correlated with both size at stocking and stocking biomass. Stocking density experiments showed that, at higher densities, growth offish was significantly reduced, but survival was not affected. The diets of juvenile Murray cod trout cod and Macquarie perch reared in fry ponds were similar. The cladocerans Moina and Daphnia, adult calanoid and cyclopoid copepods and the chironomids, Chironomus, Polypedilum and Procladius were the most commonly occurring and abundant prey. Selection for rotifers and copepod nauplii was strongly negative for all three species of fish. Size range of prey consumed was positively correlated with fish size for trout cod and Macquarie perch, but not for Murray cod. Diet composition changed as the fish grew. Early after stocking the fish into the ponds, Moina was generally the more common prey consumed, while in latter weeks, copepods and chironomids became more abundant and common in the diet. On a dry weight basis, chironomid larvae were the most important component in the diets of these fish species. Selective feeding by fish on larger planktonic species such as adult copepods and cladocerans, may have influenced the plankton community structure as proposed by the trophic cascade or top -down hypothesis. The proximate composition and energy content of Murray cod, trout cod and Macquarie perch, reared in the ponds did not vary significantly between the species, and few significant changes were observed as the fish grew. These results suggested that the nutrient requirements of these species might not vary over the size range of fish examined. Significant differences in the proximate composition of prey were observed between species, size of species and time of season. The energy content of prey (cladocerans, copepods and chironomids) on a pond basis, was closely related to the abundance of these taxa in the ponds. Data collected from all pond fillings during the present study, along with historical data from pond fillings undertaken prior to this study, were combined in a data matrix and analysed for interactions between pairs of parameters. In particular, interactions between selected water chemistry parameters, zooplankton and chironomid abundance indicators were analysed to identify key factors that influence fish production (growth, survival, condition and yield). Significant correlations were detected between fish production indicators and several water chemistry and biota (zooplankton and chironomids) parameters. However, these were not consistent across all three species of fish. These results indicated that the interactions between water chemistry, biota and fish were complex, and that combinations of these parameters, along with other factors not included in the present study, may influence fish production in these ponds. The present study, showed that more stringent monitoring of fry rearing ponds, especially water quality, zooplankton and benthos communities and fish, combined with an associated increase in understanding of the pond ecosystem, can lead to substantial improvements in pond productivity and associated fish production. In the present study this has resulted in a general increase in fish survival rates, which became less variable or more predictable in nature. The value of such knowledge can provide managers with a more predicative capacity to estimate production of ponds in support of stock enhancement programs and provision of juvenile for aquaculture grow-out.

Nutritional related aspects of the artificial propagation and larval rearing of Macquarie perch, Macquaria Australasica (Cuvier, 1830)

Studies the underlying role of nutrition in the lack of response of captive fish to hypophysation. Aspects studied include morphological characteristics, histology of ovaries, proximate analysis, fatty and amino acid profiles of oocytes, muscle, liver and diets of wild and tank-reared fish, egg and larval quality, amino acid composition of eggs and larvae at different developmental stages, larval feeding and hormone treatments.

Method and apparatus for detecting an event

Method of detecting an event in electrical apparatus (146, 148, 150). Electromagnetic radiation from the apparatus, characteristic of the event, is detected. An electrical signal is generated, this representing the electromagnetic radiation. The signal is subjected to non-stationary wave signal analysis to generate an output indicative of the detecting.

Method and apparatus for detecting an event

Method of detecting an event in electrical apparatus (146, 148, 150). Electromagnetic radiation from the apparatus, characteristic of the event, is detected. An electrical signal is generated, this representing the electromagnetic radiation. The signal is subjected to non-stationary wave signal analysis to generate an output indicative of the detecting.

Method and apparatus for haptic control

The present invention provides remote interfacing utilising haptic technology. In a first aspect there is provided a haptic grasping interface comprising a plurality of finger interaction points, with actuators connected at one end to an actuator control mechanism. The mechanism is mounted remotely from the grasping interface, inverse to the finger interaction points, for manipulation of these points. The grasping points comprise pulleys which route the actuators through a cable tension and transmission system. A second aspect provides haptic augmentation to an operator, which indicates to the operator the state of a control input to a controlled device. A third aspect provides a means of simulating motion where haptic feedback is provided to a user in correspondence with the movement of the user within a pod environment.

Method and apparatus for haptic control

The present invention provides remote interfacing utilising haptic technology. In a first aspect there is provided a haptic grasping interface comprising a plurality of finger interaction points, with actuators connected at one end to an actuator control mechanism. The mechanism is mounted remotely from the grasping interface, inverse to the finger interaction points, for manipulation of these points. The grasping points comprise pulleys which route the actuators through a cable tension and transmission system. A second aspect provides haptic augmentation to an operator, which indicates to the operator the state of a control input to a controlled device. A third aspect provides a means of simulating motion where haptic feedback is provided to a user in correspondence with the movement of the user within a pod environment.

Method and apparatus for haptic control

The present invention provides remote interfacing utilising haptic technology. In a first aspect there is provided a haptic grasping interface comprising a plurality of finger interaction points, with actuators connected at one end to an actuator control mechanism. The mechanism is mounted remotely from the grasping interface, inverse to the finger interaction points, for manipulation of these points. The grasping points comprise pulleys which route the actuators through a cable tension and transmission system. A second aspect provides haptic augmentation to an operator, which indicates to the operator the state of a control input to a controlled device. A third aspect provides a means of simulating motion where haptic feedback is provided to a user in correspondence with the movement of the user within a pod environment.

Method and apparatus for haptic control

The present invention provides remote interfacing utilising haptic technology. In a first aspect there is provided a haptic grasping interface comprising a plurality of finger interaction points, with actuators connected at one end to an actuator control mechanism. The mechanism is mounted remotely from the grasping interface, inverse to the finger interaction points, for manipulation of these points. The grasping points comprise pulleys which route the actuators through a cable tension and transmission system. A second aspect provides haptic augmentation to an operator, which indicates to the operator the state of a control input to a controlled device. A third aspect provides a means of simulating motion where haptic feedback is provided to a user in correspondence with the movement of the user within a pod environment.

Method and apparatus for haptic control

The present invention provides remote interfacing utilising haptic technology. In a first aspect there is provided a haptic grasping interface comprising a plurality of finger interaction points, with actuators connected at one end to an actuator control mechanism. The mechanism is mounted remotely from the grasping interface, inverse to the finger interaction points, for manipulation of these points. The grasping points comprise pulleys which route the actuators through a cable tension and transmission system. A second aspect provides haptic augmentation to an operator, which indicates to the operator the state of a control input to a controlled device. A third aspect provides a means of simulating motion where haptic feedback is provided to a user in correspondence with the movement of the user within a pod environment.

Self-assembled monolayers on mercury probed with a modified surface force apparatus

Self-assembled monolayers (SAMs) of three thiol compounds formed on mercury are investigated by a combination of cyclic voltammetry, electrocapillary curves, and a novel method of measuring electrical doublelayer properties. The last method involves a modified surface force apparatus in which a flat mica surface is pressed down toward a fixed mercury drop held beneath it, while both are immersed in aqueous electrolyte solution. Optical interference measurements are made of the mica-mercury separation as a function of electrical potential applied to the mercury, which yields information on the double-layer interaction between the two surfaces. Mercury is decorated by SAMs of 11-mercapto-1-undecanoic acid, which is shown to bring negative charge to the mercury/aqueous interface due to dissociation of the carboxylic acid groups; 11-mercapto-1- undecanol, which although it is uncharged changes the dipole potential of the interface; and 1-undecanethiol, which likewise changes the dipole potential, but by a different amount. The difference between the changes in dipole potential (90 mV) can be related to the different terminal groups of these two SAMs, -CH3 compared to -OH, that are in contact with the aqueous phase.