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Galaxias maculatus aquaculture objectives is to produce millions of eggs. Wild females are small (2 g), have quick sexual maturity and low mean fecundity (500 eggs/female), requiring larger fishes with higher fecundity. This study aim is to evaluate experimentally the effect of the levels of protein, lipid and dietary energy on weight increases in adults. Five independent experiments were performed at different sequential time periods at the UCT hatchery, Chile. Specimens were obtained from a) Crystalline sea return specimen catches in the Tolten estuary (4 -6 cm, 0.3-0.4 g.). b) Hatchery cultured fish. Fish were fed by hand ad libitum. In experiments 1 to 4, pelleted diets were prepared with 3 to 5 levels of protein (treatments 27 up to 57%), crumble size, three 100 L fibre ponds replicates. In experiment 5 the effect of two lipid levels (8 and 21%) was evaluated with commercial extruded Salmon Nutra Starter isoproteic crumble 1 diet at 63%, replicated in 4 ponds. The results show: A tendency to increased weight in all sizes with an increased protein level in the pelleted diet.A maximal adult growth is obtained with a diet containing a minimum of 37% crude protein, with 40% the optimal value. A higher % protein in the diet or growth in weight lower feed conversion ratio. The feed conversion ratio in the extruded diet reaches up to 0.5 and in the pelleted vary from 0.7 to 1.5. Fish 0.6 g fed with 63% protein, extruded commercial diet with two different lipid levels (8 and 21%, 20.40 and 23.84 MJ kg-1, PE/TE 0.62 and 0.71) increased weight the first month 67 and 105% each. It has been established that high-energy diets with optimal levels of protein and lipid are a good short-term solution to obtain G. maculatus of higher weight. Resumo O objetivo da aquicultura de Galaxias maculatus é produzir milhões de ovos. As fêmeas selvagens são pequenas (2 g) e têm maturidade sexual rápida e fecundidade média baixa (500 ovos/fêmea), necessitando de peixes maiores e com fecundidade superior. O objetivo deste estudo é avaliar experimentalmente o efeito dos níveis de proteínas, lipídios e energia da dieta sobre o aumento de peso em adultos. Cinco experimentos independentes foram realizados em diferentes períodos sequenciais de tempo no incubatório UCT, Chile. Os espécimes foram obtidos a partir de: a) capturas de espécimes de retorno do mar cristalino no estuário de Tolten (4-6 cm, 0,3-0,4 g); b) peixes de cultura em incubatório. Os peixes foram alimentados à mão ad libitum. Nos experimentos de 1 a 4, dietas peletizadas foram preparadas com três a cinco níveis de proteína (tratamentos 27 a 57%), tamanho do crumble, três repetições de tanques de fibra de 100 L. No experimento 5, o efeito de dois níveis de lipídios (8 e 21%) foi avaliado com dieta comercial isoproteica crumble 1 de Salmon Nutra Starter extrusada a 63%, replicada em quatro tanques. Os resultados mostram: uma tendência ao aumento de peso em todos os tamanhos, com um aumento do nível de proteína na dieta peletizada; um crescimento adulto máximo com uma dieta contendo um mínimo de 37% de proteína bruta, com 40% do valor ideal; uma porcentagem maior de proteína na dieta ou crescimento em peso com menor taxa de conversão alimentar. A taxa de conversão alimentar na dieta extrusada chega a 0,5, e na peletizada varia de 0,7 a 1,5. Peixes de 0,6 g alimentados com 63% de proteína e dieta comercial extrusada com dois níveis lipídicos diferentes (8 e 21%; 20,40 e 23,84 MJ kg-1; PE / TE 0,62 e 0,71) aumentaram de peso no primeiro mês em 67 e 105% cada, respectivamente. Foi estabelecido que dietas de alta energia com níveis ótimos de proteínas e lipídios são uma boa solução de curto prazo para obter G. maculatus de peso mais alto.

Galaxiid post-larvae constitute five of the six species in New Zealand’s iconic whitebait fishery. Distinguishing the five species needs to occur at a younger age than is convenient for easy identi...

Galaxias maculatus is a declining amphidromous fish that supports New Zealand’s culturally important whitebait fisheries targeting the migratory juvenile stage. Spawning ground protection and rehabilitation is required to reverse historical degradation and improve fisheries prospects alongside conservation goals. Although spawning habitat has been characterised in tidal rivers, there has been no previous study of spawning in non-tidal rivermouths that are open to the sea. We assessed seven non-tidal rivers over 4 months using census surveys to quantify spawning activity, identify environmental cues, and characterise fundamental aspects of the biogeography of spawning grounds. Results include the identification of compact spawning reaches near the rivermouths. Spawning events were triggered by periods of elevated water levels that were often of very short duration, suggesting that potential lunar cues were less important, and that rapid fish movements had likely occurred within the catchment prior to spawning events. Spawning grounds exhibited consistent vertical structuring above typical low-flow levels, with associated horizontal translation away from the river channel leading to increased exposure to anthropogenic stressors and associated management implications for protecting the areas concerned. These consistent patterns provide a sound basis for advancing protective management at non-tidal rivermouths. Attention to flood management, vegetation control, and bankside recreational activities is needed and may be assisted by elucidating the biogeography of spawning grounds. The identification of rapid responses to environmental cues deserves further research to assess floodplain connectivity aspects that enable fish movements in ephemeral flowpaths, and as a confounding factor in commonly used fish survey techniques.

The work is devoted to the development of a mathematical model that allows one to determine the electromagnetic fields of the microwave range inside sturgeon whitebait in order to stimulate their development. Our chosen method of calculating the mathematical model of internal electromagnetic fields in fish whitebait is planned to be used in the future for the experiment. This will increase the viability of whitebait as well as further healthy growth of sturgeon small fish and the selection of the best individuals for further artificial reproduction. A literature analysis of the influence of electromagnetic radiation on aquatic organisms and living organisms has been carried out. The effect of electromagnetic radiation on sturgeon whitebait in the first two weeks of their development is considered. In this case, the problems are solved using integro-differential equations in the case of quasi-statistics. A distinctive feature of this method is that it automatically satisfies the boundary conditions on the surface of the element. The solution of the problem of determining the electromagnetic fields inside the fish fry will be carried out taking into account its small size in comparison with the length of the falling electromagnetic radiation. In our case, as the larva grows, its size increases and the zero approximation give a rather crude result. Suggested expressions for zero, first, second, etc. approximations. Its allow take into account the growth of whitebait and the change in the ratio between their size and the incident wavelength. At the same time, it should be noted the high accuracy of this method, since already in the zero approximation its error did not exceed 15% in comparison with experimental studies of the scattering of electromagnetic fields on metal objects of ellipsoidal shape.

Whitebait comprise a culturally, commercially and recreationally important fishery in New Zealand, where post-larvae are netted while returning from their marine phase. In this study, we expanded a...

Galaxias maculatus is a declining amphidromous fish that supports culturally-important whitebait fisheries in New Zealand and elsewhere in the Pacific. As a largely annual species, the seasonal productivity of spawning grounds has a strong influence on the availability of recruits. Spawning ground protection is urgently required to reverse historical degradation and improve prospects for the maintenance of sustainable fisheries. Although spawning habitat has been well characterised in tidal rivers where it is structured by water level changes on spring high tides, there has been no previous study of spawning in non-tidal rivermouths. We assessed seven non-tidal rivers over four months using a census survey approach to quantify spawning activity, identify environmental cues, and characterise fundamental aspects of the biogeography of spawning grounds. We report conclusive results that include a) identification of compact spawning reaches near the rivermouths, b) triggering of spawning events by periods of elevated water levels that were often of very short duration, suggesting that potential lunar cues were less important and that rapid fish movements had likely occurred within the catchment prior to spawning events, and c) consistent vertical structuring of spawning grounds above typical low-flow levels with associated horizontal translation away from the river channel, leading to increased exposure to anthropogenic stressors and associated management implications for protecting the areas concerned. These consistent patterns provide a sound basis for advancing the management of non-tidal rivermouths. Attention to flood management, vegetation control, and bankside recreational activities is required and may be assisted by quantifying spawning ground biogeography. The identification of rapid responses to environmental cues deserves further research to assess implications for floodplain connectivity management to support fish movements in emphemeral flowpaths, and as a potential source of bias in commonly-used fish survey methodologies.

Galaxias maculatus (Jenyns, 1842) is a widespread freshwater fish and an important component of the economically important whitebait fisheries across the Southern Hemisphere. We report a new myxosporean parasite (Cnidaria: Myxozoa) infecting the kidney of G. maculatus from northwestern Patagonia (Argentina). Ortholinea lauquen sp. nov. was characterized using myxospore morphology, morphometrics and small subunit rDNA (ssrDNA) sequence data. Our ssrDNA phylogenetic analyses showed that O. lauquen sp. nov. is a member of the oligochaete-freshwater urinary tract clade and basal to a clade containing 4 different spore morphotypes (Chloromyxum, Myxidium, Zschokkella, Hoferellus). We explored host-parasite relationships at the macro- and microscale by analyzing the distribution, tissue tropism and pathology of O. lauquen sp. nov. Prevalence was relatively low (7%) by microscopy, but PCR detection revealed hidden levels of infection (49%), with the highest detection in lakes Morenito and Moreno (63-90%, Río Negro Province). The only locality negative by both microscopy and PCR was the Caleufu River (Neuquén Province), suggesting differences in fish life history traits (landlocked vs. potamodromous) or preference of the putative obligate invertebrate host for lentic habitats. O. lauquen sp. nov. sporulates in the renal tubules and occasionally in the glomerular space. The plasmodia frequently occluded the tubule lumina, and cellular necrosis and disintegration of the epithelium were observed. O. lauquen sp. nov. could represent a potential threat to G. maculatus culture under intensive farming conditions. Fil: Alama Bermejo, Gema. Universidad Nacional del Comahue. Centro de Investigación Aplicada y Transferencia Tecnológica en Recursos Marinos "Almirante Storni". - Provincia de Río Negro. Ministerio de Agricultura, Ganadería y Pesca. Centro de Investigación Aplicada y Transferencia Tecnológica en Recursos Marinos "Almirante Storni". Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Centro Nacional Patagónico. Centro de Investigación Aplicada y Transferencia Tecnológica en Recursos Marinos "Almirante Storni"; Argentina. Czech Academy of Sciences; República Checa Fil: Viozzi, Gustavo Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina Fil: Waicheim, María Agustina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina Fil: Flores, Verónica Roxana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina Fil: Atkinson, S. D.. State University of Oregon; Estados Unidos

Poyang Lake, the largest freshwater lake in China, is increasingly experiencing Cu crises. Combining field data, laboratory experiments, and long-term simulations, we retrieved 30 + year evolution of Cu in surface sediments (SCu). SCu evolution between 1983 and 2015 may be separated into two distinguishable periods. During the first period (1983-2003), SCu underwent a continuous increase at a mean rate of 1.80 mg/kg/yr; however, since 2003 it displayed a stepwise reduction tendency. The average SCu concentration of the entire lake in 2015 fell to 54.26 mg/kg, which is approximately 30.01% lower than that in 2003. The operation of Three Gorges Dam (TGD) markedly altered the river-lake relationship, pulled more deposited Cu along with sediment out toward the Yangtze River, and made the regions of high SCu emanate from the southeastern lake extend northwestward between 2003 and 2015. SCu in the reserves showed significant inter-annual variations, with the exception of the Jiangxi Whitebait Spawning Reserve (JWSR), where SCu generally has not been significantly impacted and has displayed no departure from the 30 + year mean of 30.57 mg/kg. The National Germplasm Reserve (NGR) and Nanjishan National Nature Reserve (NNNR) were detected with the highest SCu, with the peak concentrations, respectively, of 123.15 mg/kg and 103.1 mg/kg.

The giant kōkopu, Galaxias argenteus (Gmelin, 1789), is the largest of the galaxiid species and is endemic to New Zealand. While it was the first of the galaxiid species to be described, knowledge of its ecology remains relatively poor, particularly with respect to the reproductive phase of its life-cycle. This article describes the first observations of giant kōkopu spawning sites in the natural environment. A total of nine spawning sites have been discovered across two spawning seasons in an urban stream in Hamilton, New Zealand. Giant kōkopu are confirmed to follow a similar spawning strategy to the other whitebait species. Eggs are deposited in riparian habitats while temporarily submerged by elevated water levels. Eggs then develop terrestrially before hatching when the egg deposition sites are re-inundated during later high flows. This spawning strategy leaves giant kōkopu highly susceptible to flow regime and riparian alterations.

This study was conducted to assess the effects of flaxseed oil and dried whitebait as a source of ω-3 fatty acids (-3 FA), which could be used to produce eggs enriched with ω-3 FA, and of fructo-oligosaccharide (FOS) as a source of prebiotics on performance of hens (commercial Hy-Line Brown laying hens), and FA composition, internal quality, and sensory characteristics of the eggs. Dietary FOS increased egg weight. The amounts of α-linolenic (ALA), eicosapentaenoic (EPA) and docosahexaenoic acids (DHA) in the eggs from the hens fed the flaxseed oil alone or flaxseed oil+dried whitebait diets were higher than those of the control. Hedonic scores for off-flavor, fishy flavor, buttery taste and overall acceptability of the eggs from the hens fed the diet containing flaxseed oil+ dried whitebait were lower (p

Migratory life cycles and population structure of 2 putatively diadromous Australian fishes were examined using otolith chemistry (87Sr/86Sr) and genetics (microsatellites and mitochondrial deoxyribonucleic acid [mtDNA]). Australian whitebait (Lovettia sealii) is widely considered to be one of only a few anadromous fish species in the southern hemisphere. The congolli or tupong (Pseudaphritis urvillii) is reported to undertake an unusual form of sexually segregated catadromous migration, where females switch habitats between marine and freshwater, while males remain in marine or estuarine environments. Sr-isotope profiles of L. sealii showed this species does not move into fully freshwater habitats during its life cycle, suggesting it should be considered semi-anadromous or estuarine-dependent, rather than truly anadromous. This life-history strategy is unique among the Galaxiidae. Lovettia sealii is regionally divided into at least 3 well differentiated genetic stocks: northern and southern Tasma...

In freshwater fish, stress can often result in significant modifications to Na(+) metabolism and may be an important aspect to consider in conservation efforts; as maintaining ion balance is critical to survival and ion transport is also a key determinant of metal toxicity. In order to better quantify the response of stress, Na(+) influx, Na(+) efflux, and copper accumulation were measured as a result of handling stress in inanga (Galaxias maculatus). This species is a culturally and economically important fish in New Zealand as one of the major species in the local 'whitebait' fishery. Na(+) influx rates in inanga were found to be 2-3 times greater after handling than in 'recovered' fish, and Na(+) efflux rates increased in the range of 5-6 times. Both influx and efflux rates quickly returned to resting levels within 24h. Increases in Na(+) efflux were strongly correlated with opercular beat frequency. This suggests an increas in ventilation, and subsequent enhanced diffusive loss of Na(+), as the mechanism of increased Na(+) efflux. Total body copper levels were also measured under similar treatments. Fish had significantly higher levels of copper directly after handling than following a 24h recovery; likely due to a shared Na(+)/copper uptake pathway. As accumulation is linked to toxicity, fish exposed to elevated copper levels in stressful environments will consequently be more at risk to metal toxicity. In a natural environment, stress can come from many different sources; among which, anthropogenic disturbances can often be a cause. Given that inanga must migrate through metal-contaminated coastal regions to reach breeding habitats, they will be exposed to toxicants under conditions where perfusion and ventilation of the gill is increased. As such, ion loss would be exacerbated, leading to an enhanced compensatory ion uptake and an increase in accumulation of ion-mimicking toxicants such as copper, exacerbating toxicity. This is a concern as conservation efforts in more disruptive environments may not be adequately protected.

The water-to-organism (whole body) concentration ratio (CR wo-water ), which is defined as the ratio of the concentration of a radionuclide in the biota (Bq kg −1 fresh weight) to that in water (Bq L −1 ), has been used in mathematical models for environmental radiation protection. In the present paper, published global fallout 90 Sr, 137 Cs, 106 Ru, 144 Ce and 239+240 Pu activity concentration data and stable element concentration data for Na, K, Ca, Mg, Fe, Cu and Mn for organisms living in freshwater or seawater areas in Japan were collated. The data suitable for obtaining CR wo-water values were identified. CR wo-water values of 137 Cs were similar for pelagic fish, benthic fish and whitebait (immature, small fish) with respective geometric means of 30 (range: 4.4–69), 32 (range: 15–54) and 33 (range: 13–84). The calculated CR wo-water values of the other radionuclides and stable elements were generally similar to other previously reported values; with the exception that those for Ce were lower for marine biota and those of Cu were higher for freshwater fish.

This study described the phenology and patterns of variability of forage fish and meso- zooplankton populations near the Columbia River plume. Our objective was to identify the timing of the seasonal appearance of forage fish and to characterize the temporal patterns of abundance in relation to ocean conditions including zooplankton availability. Observations were collected at 2 sta- tions in 2008 and 2009 using 200 kHz bio-acoustic moorings, and with bi-weekly net sampling surveys conducted at nearby stations to measure total fish density and relative species composition. Acoustic time series results revealed that the seasonal timing of acoustic schools, representing the forage fishes northern anchovy Engraulis mordax, whitebait smelt Allosmerus elongatus, and Pacific sardine Sardinops sagax, occurred abruptly, with specific dates of appearance identified at each station in mid-May in both years. Both 2008 and 2009 represented very similar years for the timing and strength of wind-driven coastal upwelling. The timing of forage fish appearances in these years was linked with ocean temperature and salinity data collected at a nearby oceanographic buoy but was poorly correlated with mesozooplankton abundance, which was highly variable and fluctuating over a period of hours to days. Fluctuations in zooplankton and forage fish populations drive many trophic interactions, including juvenile salmon, seabirds, and large predators (e.g. adult salmon) that rely on the timing and abundances of these populations and have significant implications for eco- system based management.

Galaxias maculatus is an osmeriform native ¢sh of the Southern Hemisphere, in which the crystalline larvae is considered as a luxury delicacy, for this reason, it has been commercially exploited in Chile, Argentina and New Zealand. However, the ¢sheries have been rapidly decreasing due to the overexploitation and the predation of introduced species. Because of these events, there is a need to determine a carrying capacity for an intensive ¢sh culture. In order to optimize stocking densities for ¢sh culture, this paper proposes objectives to determine oxygen consumption (OC) rates, dissolved oxygen concentrations that produce signs of hypoxia and the average time elapsed between food intake and peak OC in G. maculatus. In the oxygen experiments under routine metabolism conditions, we found that G. maculatus adults and whitebait showed signs of asphyxia at dissolved oxygen concentrations between 1.3 and 2.2 mg L � 1 and that adults tolerated dissolved oxygen levels as low as1.3 mg L � 1 . The results showed that G. maculatus individuals with an average weight of 0.04 g consumed 0.048 mg O2 h � 1 , whereas individuals with an average weight of 1.4 g consumed 0.345 mg O2 h � 1 . Galaxias maculatus increased the OC rate by 31%, from 0.39 to 0.51mg O2 h � 1 g � 1 , occurring 14 min after food intake. The carrying capacities for industrial cultures of G. maculatus, were estimated using an allometric equation (OC 50.2363 � W 0.612 ), a water £ow rate of 1m 3 h � 1 and an input oxygen concentration of 10 mg L � 1 at 12 1C. The density culture of whitebait (4 g) can be allowed to reach 8^11kg m � 3 ; therefore, these stocking densities reduce the risk of hypoxia and mortality, ensuring the appropriate growth and feed conversion rates.

The growth of commercial aquaculture in Chile generated an income of $2.300 million USD in exports in 2005. Currently, 15 different species are cultivated commercially, of which seven are native; these had returns of 185 million USD. Among these native species is Galaxias maculatus (whitebait), which is endemic to Chile and figures significantly in Chilean fishing statistics. Since the 1990s, the School of Aquaculture of the Universidad Catolica de Temuco has been developing cultivation of this native species. This work presents the state of the art of the cultivation of this fish.

Objective: In the present study, we have chosen a fish Stolephorus commersonnii which is abundant in whitebait catches along Kerala coast. This fish is reported to contain higher content of essential amino acids, monounsaturated fatty acids, polyunsaturated fatty acids and minerals. The medicinal values of this species have not been reported and remain unexplored. Hence, there is a necessity to explore their uses and to conduct the pharmacological studies to ascertain their therapeutic properties. Based on literature search, no study has been carried out to scientifically validate the fish S. commersonnii possesses hepatoprotective property. Hence, this study was carried out to investigate the hepatoprotective effect of the S. commersonnii. Materials and Methods: The fish was purchased from the fish market, Ernakulam, Kerala, India. The fish were kept on ice until processed in the lab. Fish is washed and cleaned properly. The tissue is homogenized and extracted with chloroform: methanol solvent system. The extract is transferred to a dark glass container and stored in a freezer. The preliminary analysis of fish extract was carried out by simple qualitative methods. The hepatoprotective activity of Stolephorus commersonnii (SC) extract at 300 mg/kg is carried out in isoniazid induced hepatotoxic model. The albino rats of either sex were used for these studies. Results: The results of hepatoprotective study revealed that the SC extract showed a liver protective action against isoniazid induced toxicity. Conclusion: The present study suggests that the extract of S. commersonnii fish has therapeutic potential in the management of drug induced liver toxicity.

Catches of whitebait, sardine fry, sometimes contains other marine animals, including fishes, mollusks, and crustaceans, and therefore boiled and dried whitebait products may contain these marine animals if sorting is incomplete. In September 2014, contamination of boiled and dried whitebait products with pufferfish juveniles became a serious food safety concern, as tiger pufferfish Takifugu rubripes juveniles are toxic and contain tetrodotoxin (TTX). The toxicity of the juveniles of other pufferfish species, however, is unclear. To evaluate the food safety of whitebait products contaminated with pufferfish juveniles, we identified the species and toxicity of pufferfish juveniles contaminating whitebait products processed between July and September, 2014. Nucleotide sequence analysis of 16S rRNA or cytochrome b gene fragments of the mitochondrial DNA indicated that partial sequences of the polymerase chain reaction products of 15 specimens were identical with those of Lagocephalus spadiceus, and partial sequence from 2 specimens were identical with those of Takifugu vermicularis. We analyzed TTX by liquid chromatography-tandem mass spectrometry. TTX was not detected in the L. spadiceus specimens and was below the quantification limits (30 ng/g) in a T. vermicularis specimen. Based on whitebait product manufacturer's research, 795 individuals and 27.2 g of pufferfish juveniles were detected in 8,245 kg whitebait product. Thus, the ratio of pufferfish to whitebait product was estimated to be 0.096 individual/kg whitebait product and 0.0033 g/kg whitebait product, respectively.

Avoidance of predator odours by migrating Galaxias maculatus was studied in the laboratory using a two‐chamber choice tank. The odours of a native predator (short‐finned eel, Anguilla australis) and an introduced predator (rainbow trout, Oncorhynchus mykiss) were tested on both whitebait (i.e., new recruits) and juveniles. Both whitebait and juveniles exhibited avoidance behaviour when exposed to eel odours. There was no avoidance response from either the whitebait or juvenile G. maculatus when exposed to trout odours, which could suggest differences in the ability of G. maculatus to detect native and introduced predators. Observed negative effects of introduced predators on native species may be owing in part to the absence of innate avoidance behaviour in native prey species.

The acute lethality of low dissolved oxygen (DO) was examined in laboratory studies using several New Zealand freshwater fish and two invertebrates at 15°C. The 48-h LC50 value was used as the endpoint for acute DO sensitivity as, owing to rapid mortality, this was found to best approxi- mate the threshold lethal concentration. Median le- thal time to death did not provide a reliable endpoint for comparing sensitivities. Fish LC50 values varied from 0.54 to 2.65 mg litre -1 , with inanga whitebait (Galaxias maculatus; 2.65 ± 0.19 mg litre -1 , mean ± SEM) being the most sensitive species tested. Common smelt (Retropinna retropinna; 1.83 ± 0.08 mg litre -1 ) and rainbow trout (Oncorhynchus mykiss; 1.61 ± 0.06 mg litre -1 ) were similar in their sensi- tivities, whereas common bully (Gobiomorphus cotidianus; 0.91 ± 0.06 mg litre -1 ) and shortfin eel elvers (Anguilla australis; 0.54 ± 0.03 mg litre -1 ) were the most tolerant fish. The shrimp (Paratya curvirostris; 0.82 ± 0.09 mg litre -1 ) and freshwater crayfish (Koura, Paranephrops planifrons; 0.77 ± 0.06 mg litre -1 ) were also tolerant to low DO. A subset of experiments to determine the relative sensitivities of larval and juvenile trout and bully in- dicated no significant differences between these life stages. Keywords dissolved oxygen; fish; freshwater; hypoxia; Anguilla australis; Gobiomorphus cotidianus; Retropinna retropinna; Paratya curvirostris; Paranephrops planifrons; Oncorhynchus mykiss; Galaxias maculatus

We used mitochondrial (mt) DNA sequences to identify nests, emigrating larvae, and whitebait of three species of diadromous galaxiids, collected from eight locations in Taranaki and Manawatu, New Zealand. DNA was extracted from whole larvae and fin clips, and a 416 base pair (bp) sequence of mtDNA control region was determined. Four Galaxias fasciatus Gray (banded kokopu) and 12 G. postvectis Clarke (shortjaw kokopu) nests were identified. Galaxias postvectis, G. fasciatus, and G. brevipinnis Gunther (koaro) individuals were detected migrating downstream from drift samples collected between May and June 2001. Furthermore, we identified three species from samples of whitebait revealing three G. postvectis, six G. fasciatus, and three G. brevipinnis. Species of larval eggs, larvae, and whitebait can be accurately identified by molecular methods. These methods provide an opportunity to help in the understanding of nest habitat choice, hatching time, migration, and choice of rivers by whitebait species.

Galaxiids are present in many of the Andean lakes in southern South America. We studied landlocked Galaxias maculatus (Jenyns) and Galaxias platei Steindachner populations in a deep oligotrophic lake (Lake Gutierrez, Patagonia, Argentina). Their temporal and spatial distribution, intralacustrine movements (horizontal and vertical), and spawning periods were analysed using several sampling techniques (ichthyoplankton net, seine net, gill net, and baited benthic taps). We identified the early life stages of both species based on their morphology and otolith shape. The free embryos of both species migrate to the limnetic zone, where they coexist as larvae, facing the same food availability and probably the same predation risk. Each species then moves on to its own juvenile and adult habitat: the littoral and benthic zone for G. maculatus and only the deeper benthic zone for G. platei. Their adult habitats and part of their spawning periods partly overlap.

Laboratory experiments demonstrated that migrant juvenile banded kokopu (Galaxias fasciatus Gray) were more sensitive to suspended sediment (SS) than other native fish species. If juvenile migrants avoid waters made turbid by SS and their recruitment to adult habitats up stream is reduced, then adult abundance may decline in turbid rivers. To test this, we compared the abundance of diadromous native fish between turbid and clear rivers. The duration (% time) for which SS concentrations exceeded 120 mg litre‐1 (a critical level from laboratory experiments) during the migration season (August‐December) was estimated for over 150 New Zealand river sites. Turbid rivers were defined as those where SS concentrations exceeded 120 mg litre‐1 for over 20% of the time and clear rivers as those where SS concentrations exceeded 120 mg litre‐1 for less than 10% of the time. Eight turbid rivers and seven clear ones were identified where sufficient data on SS and native fish populations existed to permit a comp...

カルシウムの可溶化と食品としての嗜好性の両面から,しらす干しに対する柑橘果汁もしくは米酢の添加について検討を行った.柑橘果汁もしくは米酢を添加したしらす干しからのカルシウムの可溶化率は,いずれも添加量の増加に伴って上昇した.パネルによる嗜好評価から,スダチ果汁を20%添加したしらす干しが,味,匂い及び総合評価において最も好まれた.以上の結果から,柑橘果汁を添加したしらす干しの食品開発にあたっては,カルシウムの可溶化率のみならず,嗜好性とのバランスを考慮に入れた条件設定が必要であると推察した.

The tolerances of seven New Zealand freshwater fish species and one species of shrimp to low levels of dissolved oxygen were determined in the laboratory by holding fish at dissolved oxygen levels of 1, 3, or 5 mg litre‐1 for 48 h at 15°C. Juvenile rainbow trout (Oncorhynchus mykiss) were also tested for comparison. All of the banded kokopu whitebait (Galaxias fasciatus), juvenile torrentfish (Cheimarrichthys fosteri), adult and juvenile common smelt (Retropinna retropinna), juvenile common bully (Gobiomorphus cotidianus), and trout were dead after 48 h exposure to 1 mg litre‐1. Adult and juvenile inanga (Galaxias maculatus), adult common bully (Gobiomorphus cotidianus), and shrimp (Paratya curvirostris) had mortalities ranging from 27 to 80% at 1 mg litre‐1, whereas all of the elvers (Anguilla spp.) survived. Juvenile rainbow trout were the most sensitive of the species tested, and the only species that had mortalities during exposure to 3 mg litre‐1. No deaths of any fish occurred at 5 mg litre...

The fatty acid profile of the galaxiid fish Galaxias maculatus (Salmoniformes) collected from an estuarine habitat (a river mouth), a freshwater creek and two land-locked freshwater lakes in Victoria, Australia, were investigated with a view to evaluating habitat influences on the fatty acid profile. Fish from the freshwater creek were unpigmented, fresh-run juveniles (referred to as whitebait), the others adult fish. The fatty acids that predominated in adult G. maculatus muscle were 16:0 and 22:6(n-3), and 16:0 and 18:1(n-9), respectively. In whitebait 22:6(n-3), 20:5(n-3) and 16:0 were predominant. Hopkins estuary fish had the highest amount of 18:2(n-6) but the lowest 18:3(n-3). In all galaxiid populations, polyunsaturated fatty acids (PUFA) were the main group of fatty acids in total lipid in muscle, and accounted for more than 40 %, followed by saturates and monoenes. In landlocked populations, the amount of monoenes was lower than in other galaxiid populations. G. maculatus whitebait had significantly lower amount of saturates and the highest amount of n-3 fatty acids. The ratio of n-3 to n-6 PUFA ranged from 4.6 (Hopkins estuary) to 7.6 (whitebait), and the former differed significantly from all the other populations. The main fatty acids predominating in the liver of galaxiids from landlocked (Lake Bullen Merri) and estuarine populations were 16:0, 22:6(n-3) and 18:1 (n-9), and generally reflected the corresponding pattern in muscle. A principal component analysis of the fatty acid composition of muscle samples confirmed and highlighted the distinct fatty acid profile of the populations investigated, when three groupings could be discerned. The study suggests that in addition to the diet, other habitat related factors may influence the fatty acid profile in catadromous G. maculatus .

Laboratory tank experiments were used to determine the effect of turbidity levels ranging from 0–640 Nephelometric Turbidity Units (NTU) on mean feeding rates for each species. Mean feeding rates for banded kokopu (Galaxias fasciatus), smelt (Retropinna retropinna), inanga (G. maculatus), and common bullies (Gobiomorphus cotidianus) were all reduced by increased turbidity, but significantly so only for banded kokopu and inanga. Banded kokopu was the most sensitive species as feeding rates at 20 NTU were significantly lower than in clear water, compared with levels over 160 NTU for the other species. Feeding rates for redfinned bullies (Gobiomorphus huttoni) increased with turbidity up to 40 NTU then decreased. Reductions in feeding rate at elevated turbidity levels were the result of a reduced inability to feed, rather than to stress, as exposure to the highest turbidity level did not reduce feeding motivation or appetite. Feeding tests in the dark indicated that, whereas vision was important for...

Despite the well known importance of ω-3 polyunsaturated fatty acids (PUFA) in marine and freshwater fish larvae, there are few studies on how essential fatty acid requirements and composition on whole body can be altered by changes in water salinity. The present study aimed to determine the effect of salinity on ω-3 PUFA requirements, larval growth survival and fatty acid composition of Galaxias maculatus larvae cultured at two different salinities (0 and 15 g L-1) for 20 days while fed rotifers containing two different levels of ω-3 PUFA (1.87 and 3.16%). The results denoted a marked difference in ω-3 PUFA requirements and in the pattern of fatty acid deposition in the whole body of larvae reared at different salinities, depending of ω-3 PUFA in diets. Thus, to improve growth and survival larvae of G. maculatus reared at 0 g L-1 require higher levels of ω-3 PUFA, principally 18:3 ω-3. Larvae reared at salinities of 15 g L-1 require low levels of ω-3 PUFA for optimal survival, especially 18:3 ω-3. Eicosapentaenoic acid and docosahexaenoic acid content in the whole body of larvae was also affected by water salinity.