Journal articles on the topic 'Fish populations Victoria'
To see the other types of publications on this topic, follow the link: Fish populations Victoria.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Fish populations Victoria.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Klanten, O. Selma, Michelle R. Gaither, Samuel Greaves, Kade Mills, Kristine O’Keeffe, John Turnbull, Rob McKinnon, and David J. Booth. "Genomic and morphological evidence of distinct populations in the endemic common (weedy) seadragon Phyllopteryx taeniolatus (Syngnathidae) along the east coast of Australia." PLOS ONE 15, no. 12 (December 23, 2020): e0243446. http://dx.doi.org/10.1371/journal.pone.0243446.
Full textAbstract:
The common or weedy seadragon, Phyllopteryx taeniolatus, is an iconic and endemic fish found across temperate reefs of southern Australia. Despite its charismatic nature, few studies have been published, and the extent of population sub-structuring remains poorly resolved. Here we used 7462 single nucleotide polymorphisms (SNPs) to identify the extent of population structure in the weedy seadragon along the temperate southeast coast of Australia. We identified four populations, with strong genetic structure (FST = 0.562) between them. Both Discriminant Analysis of Principle Components (DAPC) and Bayesian clustering analyses support four distinct genetic clusters (north to south: central New South Wales, southern NSW, Victoria and Tasmania). In addition to these genetic differences, geographical variation in external morphology was recorded, with individuals from New South Wales shaped differently for a few measurements to those from the Mornington Peninsula (Victoria). We posit that these genetic and morphological differences suggest that the Victorian population of P. taeniolatus was historically isolated by the Bassian Isthmus during the last glacial maximum and should now be considered at least a distinct population. We also recorded high levels of genetic structure among the other locations. Based on the genomic and to a degree morphological evidence presented in this study, we recommend that the Victorian population be managed separately from the eastern populations (New South Wales and Tasmania).
2
Koster, W. M., D. R. Dawson, J. R. Morrongiello, and D. A. Crook. "Spawning season movements of Macquarie perch (Macquaria australasica) in the Yarra River, Victoria." Australian Journal of Zoology 61, no. 5 (2013): 386. http://dx.doi.org/10.1071/zo13054.
Full textAbstract:
The Macquarie perch (Macquaria australasica) is a threatened fish species that inhabits rivers and impoundments in south-eastern Australia. Previous studies have shown that Macquarie perch in impoundments exhibit synchronised upstream spawning migrations to shallow, fast-flowing habitats in the lower reaches of inflowing streams. There has been little study of movement behaviours of entirely riverine populations of Macquarie perch despite this being the species’ natural habitat. Here, radio-telemetry is used to test the hypothesis that riverine populations exhibit synchronised migrations during the spawning season. Thirty Macquarie perch in the Yarra River, Victoria, a translocated population outside of the species’ natural range, were radio-tagged before the late spring–early summer spawning season and their movements followed over a 10-month period (May 2011 to February 2012). Tagged fish typically occupied restricted reaches of stream (<450 m). Sixteen of the fish undertook occasional upstream or downstream movements (~250–1000 m) away from their usual locations, particularly associated with large flow variations during the spawning season. There was no evidence of synchronised migratory behaviour or movement of multiple fish to specific locations or habitats during the spawning season. Whilst further research over more years is needed to comprehensively document the spawning-related behaviours of riverine Macquarie perch, our study demonstrates that management of riverine populations of this threatened species cannot necessarily be based on the model of spawning behaviour developed for lacustrine populations.
3
Olwa, Richard, Herbert Nakiyende, Elias Muhumuza, Samuel Bassa, Anthony Taabu-Munyaho, and Winnie Nkalubo. "Ecology of the Critically Endangered Singidia Tilapia (Teleostei: Cichlidae: Oreochromis esculentus) of lake Kayanja, Uganda and its conservation implications." Journal of Threatened Taxa 12, no. 10 (July 26, 2020): 16251–56. http://dx.doi.org/10.11609/jott.5700.12.10.16251-16256.
Full textAbstract:
Singidia Tilapia Oreochromis esculentus is a Critically Endangered native tilapia fish species endemic to lakes Victoria and Kyoga basins of East Africa, however, it disappeared from these main lakes due to overfishing, environmental degradation and predation by the introduced Nile Perch Lates niloticus. Remnant populations of this fish species is now restricted to satellite lakes including Lake Kayanja of the Victoria basin. This study provides updated information about the population abundance, critical habitat, threats and diet of Singidia Tilapia to inform conservation decisions to revive its populations in the wild. Fish data collection and mapping of nursery and breeding habitats of Singidia Tilapia on Lake Kayanja was conducted between February 2016 and October 2017. In all the areas mapped and sampled, Singidia Tilapia (with a size range of 11–27 cm TL) was the most abundant (43%) relative to exotic Nile Tilapia Oreochromis niloticus (21%) and Redbelly Tilapia Coptodon zillii (36%). The emergence of introduced (exotic) tilapias like Nile Tilapia recorded in this study could be attributed to cage fish farming being carried out in this Lake. The diet of Oreochromis esculentus consisted mainly of detritus (60.8 %), plant materials (27.7%) and blue-green algae (5.5%). Destruction of critical habitats and presence of introduced fish species were noted as the major threats to this fish and its habitats. The generated information could contribute to guiding stakeholders to undertake appropriate actions to conserve this threatened fish species and its habitats.
4
Barbee, Nicole C., Robin Hale, John Morrongiello, Andy Hicks, David Semmens, Barbara J. Downes, and Stephen E. Swearer. "Large-scale variation in life history traits of the widespread diadromous fish, Galaxias maculatus, reflects geographic differences in local environmental conditions." Marine and Freshwater Research 62, no. 7 (2011): 790. http://dx.doi.org/10.1071/mf10284.
Full textAbstract:
Applying uniform population models and management strategies to widespread species can be ineffective if populations exhibit variable life histories in response to local conditions. Galaxias maculatus, one of the world’s most widely distributed fish species, occurs in a broad range of habitats and is highly adaptable, making it an ideal species for examining variation in life history traits across large geographic scales. Here, we examine the spawning biology and early life history of diadromous G. maculatus in coastal rivers in Victoria, Australia, and compare them to other populations throughout its range. We predicted that traits associated with these critical life stages, especially those that respond to environmental conditions that vary geographically, such as seasonal cues and temperature, are likely to vary across large spatial scales. We found that spawning occurs later in Victoria than in New Zealand (NZ) and South America, but migration back to rivers occurs at the same time in Victoria and NZ, but not South America. G. maculatus returning to rivers are also smaller and younger in Victoria than those in NZ. Other traits, like some attributes of spawning schools and spawning habitats, did not vary across large scales. Researchers and managers should be cautious when making broad assumptions about the biology of widely distributed species.
5
Getabu, A. "Spatial distribution and temporal changes in the fish populations of Lake Victoria." Aquatic Living Resources 16, no. 3 (July 2003): 159–65. http://dx.doi.org/10.1016/s0990-7440(03)00008-1.
Full text
6
Crook, David A., Jed I. Macdonald, and Tarmo A. Raadik. "Evidence of diadromous movements in a coastal population of southern smelts (Retropinninae: Retropinna) from Victoria, Australia." Marine and Freshwater Research 59, no. 7 (2008): 638. http://dx.doi.org/10.1071/mf07238.
Full textAbstract:
Understanding the migratory behaviour of fishes is critical to the conservation and management of fish assemblages in coastal rivers. We analysed the otolith chemical signatures of smelt, Retropinna sp., from inland and coastal populations in mainland south-eastern Australia to determine whether individuals within coastal populations of the species were diadromous. Assessments of otolith chemical composition combined with water chemistry data were used to make inferences about the migration histories of individual fish. A proportion of the smelt collected from the freshwater reaches of a coastal river exhibited diadromous movements, with the majority of fish analysed showing evidence of estuarine or marine occupation as larvae/juveniles and a minority inhabiting freshwater throughout their life histories. A broad range in the daily ages of upstream migration into freshwater (15–106 days) and the timing of these migrations suggest that spawning and migration occur over several months during the summer/autumn period. The results of this study suggest that southern smelts are an ecologically variable taxonomic group and that conservation and management actions should take into account the range of migratory behaviours exhibited both within populations and across regions.
7
Appleford, P., T. A. Anderson, and G. J. Gooley. "Reproductive cycle and gonadal development of Macquarie perch, Macquaria australasica Cuvier (Percichthyidae), in Lake Dartmouth and tributaries of the Murray - Darling Basin, Victoria, Australia." Marine and Freshwater Research 49, no. 2 (1998): 163. http://dx.doi.org/10.1071/mf97012.
Full textAbstract:
The gonadal development, reproductive cycle and growth of Macquarie perch, Macquaria australasica Cuvier, in Lake Dartmouth and selected tributaries of the Murray–Darling River Basin in south-eastern Australia were evaluated. Gonadosomatic index (GSI) and histological analysis were used to determine gonadal development and age and size at first maturity in the resident Lake Dartmouth population. GSI analysis was also used to determine age and size of Macquarie perch at first maturity in the inflowing Mitta Mitta River and other riverine populations within the Goulburn River catchment. Males appeared slightly smaller at first spawning than females at all sites; both sexes were fully mature at four years of age. Differences in size at first maturity were found between the lake and river populations; both males and females of river populations tended to mature at a much smaller size than the fish resident in the lake. Spawning occurred around November. Ovarian and testicular development in this species follows a pattern similar to that of other native Australian percichthyids. The implications for management of recreational fisheries based on minimum size regulations is discussed in relation to site-specific differences in growth rates and size of first maturity of fish.
8
Langdon, JS. "Haemosiderosis in Platycephalus bassensis and Diodon nicthemerus in south-east Australian coastal waters." Marine and Freshwater Research 37, no. 5 (1986): 587. http://dx.doi.org/10.1071/mf9860587.
Full textAbstract:
The degree of haemosiderin deposition in the spleen, liver, and kidney of P. bassensis and D. nicthemerus was compared in specimens from Port Phillip Bay, and Lakes Entrance, Victoria, Bass Strait, and the Derwent estuary, Tasmania. D. nicthemerus displayed extensive visceral haemosiderosis and fatty infiltration of the liver at all sites, apparently as normal conditions. P. bassensis from Port Phillip Bay displayed severe visceral haemosiderosis, whereas specimens from the remaining sites had only low background levels of haemosiderin deposition. It is suggested that high levels of visceral haemosiderin in fish species normally displaying low levels are indicative of a suboptimal health status in fish populations. No infectious cause of the haemosiderosis in Port Phillip Bay fish has been identified, and toxic or pollution-related causes are thus considered likely to be responsible.
9
Onyuka, JHO, R. Kakai, PF Arama, and AVO Ofulla. "Comparison of antimicrobial activities of brine salting, chlorinated solution and Moringa oleifera plant extracts in fish from Lake Victoria basin of Kenya." African Journal of Food, Agriculture, Nutrition and Development 13, no. 58 (July 10, 2013): 7772–88. http://dx.doi.org/10.18697/ajfand.58.11260.
Full textAbstract:
Chemical preservatives can be used to reduce the overall microbial populations in fish and fish products. This study was set to determine the antimicrobial activities of brine salting, chlorinated solution, and Moringa oleifera plant extracts treatments on enteric bacteria in Rastrineobola argentea and Oreochromis niloticus fish collected from beaches and markets in Lake Victoria basi n of western Kenya. Using a cross-sectional samples collection design, fresh fish ( Rastrineobola argentea and Oreochromis niloticus ) samples were randomly collected from three fish landing beaches (Dunga, Luanda Rombo and Sirongo) and from three markets (Kisumu, Luanda and Bondo), in the Lake Victoria Basin of western Kenya and take n to the laboratory within 4 hours for processing and treatments with preservatives. The preservatives were sodium chloride solutions (3%, 6%, 9% and 12%), sodi um hypochlorite (50ppm, 100ppm, 150ppm and 200ppm), and Moringa oleifera n-hexane and ethanol ex tract solutions (20μg/ml, 40μg/ml, 60μg/ml, and 80μg/ml), respectively. The treatments were done for 0hrs, 2hrs, 4hrs, 6hrs and 8hrs, before bacteria growth analysis using most probable number and aerobic plate count methods. Statistical differences in effectiveness of the preservatives was determined by one factor ANOVA with P<0.05 value considered statistically significant. The results showed that with increase in salt concentration and after 8 hours treatment duration, there was a significant reduction of microbial load in R. argentae and O. niloticus fish samples, P<0.05, one factor ANOVA. The effectiveness of chlorinated solution (sodium hypochlorite) against the bacteria decreased with time but increased with increase in concentration. As M. oleifera n-hexane and ethanol extracts concentrations increased and after 8 hours treatment duration, there was significant decrease in microbial loads, P<0.001 by one factor ANOVA. Over all, sodium chloride at 12% concentration was the most effective and chlorine solution even at 200ppm was the least effective while the M. oleifera plant extrtional sodium chloride, M. oleifera plant extracts can also be used as antimicrobial agent for processing and preservation of fish.
10
Konijnendijk, N., D. A. Joyce, H. D. J. Mrosso, M. Egas, and O. Seehausen. "Community Genetics Reveal Elevated Levels of Sympatric Gene Flow among Morphologically Similar but Not among Morphologically Dissimilar Species of Lake Victoria Cichlid Fish." International Journal of Evolutionary Biology 2011 (November 24, 2011): 1–12. http://dx.doi.org/10.4061/2011/616320.
Full textAbstract:
We examined genetic structure among five species of Lake Victoria haplochromine cichlids in four island communities, using a full factorial sampling design that compared genetic differentiation between pairs of species and populations of varying morphological similarity and geographical proximity. We found that allopatric conspecific populations were on average significantly more strongly differentiated than sympatric heterospecific populations of morphologically similar species. Allopatric heterospecific populations of morphologically dissimilar species were most differentiated. Our work demonstrates that phenotypic divergence can be maintained and perhaps even evolve in sympatry despite considerable gene flow between species. Conversely, phenotypic resemblance among conspecific populations can be maintained despite geographical isolation. Additionally we show that anthropogenically increased hybridization does not affect all sympatric species evenly but predominantly affects morphologically similar and closely related species. This has important implications for the evolution of reproductive isolation between species These findings are also consistent with the hypothesis of speciation reversal due to weakening of divergent selection and reproductive isolation as a consequence of habitat homogenization and offers an evolutionary mechanistic explanation for the observation that species poor assemblages in turbid areas of the lake are characterized by just one or two species in each of a few morphologically distinct genera.
11
Harris, Les N., Jean-Sébastien Moore, Christopher G. McDermid, and Heidi K. Swanson. "Long-distance anadromous migration in a fresh water specialist: the Lake Trout (Salvelinus namaycush)." Canadian Field-Naturalist 128, no. 3 (October 16, 2014): 260. http://dx.doi.org/10.22621/cfn.v128i3.1604.
Full textAbstract:
The Lake Trout, Salvelinus namaycush, is believed to be one of the most saline intolerant salmonid species, typically completing its life wholly in fresh water. Historical observations and more recent quantitative assessments have shown, however, that in some Arctic populations, Lake Trout can migrate to marine waters (i.e., display anadromy). In the four coastal Arctic populations of Lake Trout where anadromy has been confirmed, migrations to and from marine environments are relatively short (i.e., in the order of a few kilometres). In the Halokvik River on Victoria Island, we captured two anadromous Lake Trout in a weir used jointly for commercial fishing and stock assessment research. Both fish were captured during the fall upstream migration, some 50 km from their presumed fresh water spawning or overwintering locations. This observation extends the current knowledge regarding the distribution of anadromous populations in this species and suggests that migration to marine habitats can be much longer than previously expected.
12
Tonkin, Zeb, Joanne Kearns, Justin O'Mahony, and John Mahoney. "Spatio-temporal spawning patterns of two riverine populations of the threatened Macquarie perch (Macquaria australasica)." Marine and Freshwater Research 67, no. 11 (2016): 1762. http://dx.doi.org/10.1071/mf15319.
Full textAbstract:
Understanding species-reproduction dynamics is vital for the management of riverine fish. Information on the spawning ecology of the endangered Australian Macquarie perch (Macquaria australasica) is based largely on data gathered from lacustrine populations, with uncertainty on the applicability such data has for managing riverine populations. The current study presents a first description of spawning patterns of two riverine populations of Macquarie perch in Victoria, Australia, using egg counts recorded across multiple sites and periods within the species core spawning window. Spawning intensity was highly variable between study sites, with 96 and 82% of eggs collected from a single site in the King Parrot Creek and Yarra River respectively. We also found a strong positive association between spawning and water temperature. Our results provide an important account of spatio-temporal spawning patterns of riverine Macquarie perch populations and lend some support for the transfer of information from lacustrine populations (as demonstrated by spawning habitat and temperature association). Although the spatial and temporal constraints of the present study must be considered, the results provide opportunity for further testing of the environmental effects, and management options aimed at enhancing spawning of this endangered species.
13
Schmidt, Daniel J., Joel A. Huey, Nick R. Bond, and Jane M. Hughes. "Population structure of sexually reproducing carp gudgeons: does a metapopulation offer refuge from sexual parasitism?" Marine and Freshwater Research 64, no. 3 (2013): 223. http://dx.doi.org/10.1071/mf12305.
Full textAbstract:
Australian carp gudgeons (Hypseleotris spp.) of the Murray–Darling basin are a species complex including sexually reproducing taxa and unisexual hybrid lineages that reproduce via hybridogenesis. Unisexual fish require gametes of a sexual species to propagate themselves and can be regarded as ‘sexual parasites’ capable of driving closed populations to extinction. Metapopulation dynamics have been proposed as a mechanism that could facilitate coexistence between a sexual parasite and its ‘host’. This study evaluates whether patterns of spatial genetic variation are compatible with metapopulation dynamics for a sexually reproducing member of the carp gudgeon complex (Hypseleotris sp. HA), in the Granite Creeks system of central Victoria. Genetic differentiation of fish among all study sites was accommodated by a model of migration-drift equilibrium using decomposed pairwise regression analysis. Given that the population was divided into discrete patches in the form of refugial waterholes during the time of this study, we infer that spatially constrained source–sink metapopulation dynamics may be responsible for producing this pattern. It is therefore possible that metapopulation dynamics contribute to coexistence in the Granite Creeks carp gudgeon hybridogenetic system, and further analysis is required to determine the relative importance of environmental versus demographic factors towards patch extinction.
14
Morgan, Jess A. T., Wayne D. Sumpton, Andrew T. Jones, Alexander B. Campbell, John Stewart, Paul Hamer, and Jennifer R. Ovenden. "Assessment of genetic structure among Australian east coast populations of snapper Chrysophrys auratus (Sparidae)." Marine and Freshwater Research 70, no. 7 (2019): 964. http://dx.doi.org/10.1071/mf18146.
Full textAbstract:
Snapper Chrysophrys auratus is a high-value food fish in Australia targeted by both commercial and recreational fisheries. Along the east coast of Australia, fisheries are managed under four state jurisdictions (Queensland, Qld; New South Wales, NSW; Victoria, Vic.; and Tasmania, Tas.), each applying different regulations, although it is thought that the fisheries target the same biological stock. An allozyme-based study in the mid-1990s identified a weak genetic disjunction north of Sydney (NSW) questioning the single-stock hypothesis. This study, focused on east-coast C. auratus, used nine microsatellite markers to assess the validity of the allozyme break and investigated whether genetic structure exists further south. Nine locations were sampled spanning four states and over 2000km, including sites north and south of the proposed allozyme disjunction. Analyses confirmed the presence of two distinct biological stocks along the east coast, with a region of genetic overlap around Eden in southern NSW, ~400km south of the allozyme disjunction. The findings indicate that C. auratus off Vic. and Tas. are distinct from those in Qld and NSW. For the purpose of stock assessment and management, the results indicate that Qld and NSW fisheries are targeting a single biological stock.A
15
KRUUK, H., and P. C. GOUDSWAARD. "Effects of changes in fish populations in Lake Victoria on the food of otters (Lutra maculicollis Schinz and Aonyx capensis Lichtenstein)." African Journal of Ecology 28, no. 4 (December 1990): 322–29. http://dx.doi.org/10.1111/j.1365-2028.1990.tb01167.x.
Full text
16
Hamer, Paul A., and Gregory P. Jenkins. "High levels of spatial and temporal recruitment variability in the temperate sparid Pagrus auratus." Marine and Freshwater Research 55, no. 7 (2004): 663. http://dx.doi.org/10.1071/mf04024.
Full textAbstract:
Knowledge of spatial and temporal variation in the abundance of early life stages is important to developing an understanding of juvenile recruitment processes and, ultimately, the dynamics and demographics of fish populations. In Victoria, south-eastern Australia, snapper, Pagrus auratus, supports an important fishery characterised by high variability in year-class strength. We investigated spatial and temporal variation in the recruitment of small juvenile (0+) snapper by monitoring their abundance in four bay and inlet nursery areas during four consecutive summer/autumn recruitment periods (2000–2003). We found considerable spatial variability in the abundance of recruits, both within and among inlets. Interannual recruitment variation, however, differed among inlets. Recruitment into the largest nursery area and most important fishery, Port Phillip Bay, varied by ~10-fold across years, whereas variation for the other inlets was low or not significant. There were also clear differences in size distributions of recruits among both inlets and years. Strong recruitment in Port Phillip Bay during 2001 was related to a longer period of spawning and successful larval settlement and was associated with above average water temperatures. Future monitoring of 0+ recruitment in Victoria and studies of the recruitment processes should be specific to individual nursery areas.
17
Muschick, Moritz, James M. Russell, Eliane Jemmi, Jonas Walker, Kathlyn M. Stewart, Alison M. Murray, Nathalie Dubois, J. Curt Stager, Thomas C. Johnson, and Ole Seehausen. "Arrival order and release from competition does not explain why haplochromine cichlids radiated in Lake Victoria." Proceedings of the Royal Society B: Biological Sciences 285, no. 1878 (May 9, 2018): 20180462. http://dx.doi.org/10.1098/rspb.2018.0462.
Full textAbstract:
The frequent occurrence of adaptive radiations on oceanic islands and in lakes is often attributed to ecological opportunity resulting from release from competition where arrival order among lineages predicts which lineage radiates. This priority effect occurs when the lineage that arrives first expands its niche breadth and diversifies into a set of ecological specialists with associated monopolization of the resources. Later-arriving species do not experience ecological opportunity and do not radiate. While theoretical support and evidence from microbial experiments for priority effects are strong, empirical evidence in nature is difficult to obtain. Lake Victoria (LV) is home to an exceptional adaptive radiation of haplochromine cichlid fishes, where 20 trophic guilds and several hundred species emerged in just 15 000 years, the age of the modern lake that was preceded by a complete desiccation lasting several thousand years. However, while about 50 other lineages of teleost fish also have established populations in the lake, none of them has produced more than two species and most of them did not speciate at all. Here, we test if the ancestors of the haplochromine radiation indeed arrived prior to the most competent potential competitors, ‘tilapias’ and cyprinids, both of which have made rapid radiations in other African lakes. We assess LV sediment core intervals from just before the desiccation and just after refilling for the presence of fossil fish teeth. We show that all three lineages were present when modern LV began to fill with water. We conclude that the haplochromines' extraordinary radiation unfolded in the presence of potentially competing lineages and cannot be attributed to a simple priority effect.
18
Chibwana, F. D., and G. Nkwengulila. "Variation in the morphometrics of diplostomid metacercariae (Digenea: Trematoda) infecting the catfish, Clarias gariepinus in Tanzania." Journal of Helminthology 84, no. 1 (July 21, 2009): 61–70. http://dx.doi.org/10.1017/s0022149x09990083.
Full textAbstract:
AbstractDiplostomum species are economically important worldwide due to their metacercariae which parasitize the eyes of fish, in both natural and aquaculture systems. However, their striking morphological similarity, especially at the metacercarial stage, makes species separation difficult. Three closely related diplostomid metacercariae, namely Diplostomum mashonense (type 3), Tylodelphys sp. 1 and 2 (type 1 and 2, respectively), coexist in the cranial cavity of the catfish, Clarias gariepinus from Mindu dam, Lake Victoria, Msimbazi, Ruvu and Kilombero rivers. The morphometrics of these three species were analysed by discriminant function analysis to investigate the degree of variation among the populations from the five localities sampled. The first canonical functions for all visual examination plots accounted for over 50% of the between-group variability. The observed differences were mainly from measurements associated with length, indicating that these measurements are important in the description of population characteristics. Visual examination of the samples along the canonical functions showed a clear between-population differentiation. The overall random assignment of individuals into their original groups was high (97%). These extensive morphometric variations introduce doubt about the reliability of measurements in the determination of species in these trematodes, as they may lead to misidentifications.
19
Kwetegyeka, Justus, George Mpango, and Otto Grahl-Nielsen. "Variation in Fatty Acid Composition in Muscle and Heart Tissues among Species and Populations of Tropical Fish in Lakes Victoria and Kyoga." Lipids 43, no. 11 (August 19, 2008): 1017–29. http://dx.doi.org/10.1007/s11745-008-3200-7.
Full text
20
Chua, A. S. M., K. Eales, T. Mino, and R. Seviour. "The large PAO cells in full-scale EBPR biomass samples are not yeast spores but possibly novel members of the β-Proteobacteria." Water Science and Technology 50, no. 6 (September 1, 2004): 123–30. http://dx.doi.org/10.2166/wst.2004.0368.
Full textAbstract:
Large, homogenous clusters of coccobacilli were found to be abundant in the biomasses from a conventional plant at Rosebud, Victoria, Australia. The identity and the in situ physiology of these dominant microorganisms were investigated in this study. These large clustered cells were revealed to be neither Gram positive nor Gram negative bacteria and contain polyP granules. Cells with similar features were also observed in some enhanced biological phosphate removal (EBPR) systems and reported as yeast spores and Rhodocyclus-related polyphosphate accumulating organisms (PAOs). In this study, fluorescent in situ hybridization (FISH) probing showed these cells were prokaryotic and members of the β-Proteobacteria. However, these large clustered cells did not respond to the PAO mix FISH probes. The in situ physiology of these large cells was studied with FISH in combination with microautoradiography (MAR) in order to understand their substrate assimilation abilities under different conditions as well as their phosphate uptake ability. These cells were able to take up acetate, glutamate and aspartate, but not glucose under both aerobic and anaerobic conditions. Nile Blue A staining in combination with MAR showed that cells incubated under anaerobic conditions contained polyhydroxyalkanoates (PHA) granules. In addition, MAR showed aerobic 33Pi assimilation with all these substrates, consistent with them supporting an EBPR capacity in these large cells. As well as raising doubts about a role for yeasts in EBPR, this study suggests that much still needs to be learned about the identity and level of biodiversity of the PAO in EBPR systems, and emphasizes the benefits of using techniques like FISH/MAR and PHA staining/MAR to resolve the in situ physiology of the populations of interest there.
21
Jenkins, Gregory P., Megan Shaw, and Bryce D. Stewart. "Spatial Variation in Food-Limited Growth of Juvenile Greenback Flounder, Rhombosolea tapirina: Evidence from Otolith Daily Increments and Otolith Scaling." Canadian Journal of Fisheries and Aquatic Sciences 50, no. 12 (December 1, 1993): 2558–67. http://dx.doi.org/10.1139/f93-279.
Full textAbstract:
Growth rates of juvenile flounder, Rhombosolea tapirina, determined from daily increment number, and the relationship between otolith and fish sizes (otolith scaling), were compared between two adjacent areas. Swan Bay, Victoria, a sheltered bay with a well-developed seagrass-detrital system, supports higher populations of prey and feeding rates of juvenile flounder than Port Phillip Bay, an area more exposed to waves and tidal currents. Temperature was significantly higher in Swan Bay (though generally less than 1 °C). Growth rates determined from daily increment number were similar within bays, but significantly different between bays. The pooled growth rate for Swan Bay (0.29 mm∙d−1) was significantly higher than for Port Phillip Bay (0.17 mm∙d−1). The same pattern was found for otolith scaling. Most of the variation in growth rates between the two bays was apparently related to food supply. A laboratory experiment indicated that otolith growth rate had a minimum level which was independent of somatic growth rate, and an additional component which was highly correlated with somatic growth rate. This resulted in an exponential decrease in otolith growth per unit somatic growth with increasing somatic growth rate such that variation in otolith scaling would be greatest at low growth rates.
22
Letnic, Mike, and Greg Connors. "Changes in the distribution and abundance of saltwater crocodiles (Crocodylus porosus) in the upstream, freshwater reaches of rivers in the Northern Territory, Australia." Wildlife Research 33, no. 7 (2006): 529. http://dx.doi.org/10.1071/wr05090.
Full textAbstract:
Since they were declared a protected species in 1971, populations of saltwater crocodiles (Crocodylus porosus) have increased in the tidal rivers, freshwater swamps and marine waters of the Northern Territory. The recovery of the C. porosus population has been accompanied by an increase in the incidence of ‘problem crocodiles’ that represent a threat to people in freshwater and marine habitats. Despite the implications for human safety, little is known about C. porosus populations in the freshwater reaches of rivers, well upstream of tidal influence. In this study, we examined the density and body-size structure of C. porosus populations in three freshwater rivers using a combination of data from spotlight and helicopter surveys conducted between the 1980s and 2005, and the inland extent of C. porosus using distribution records in the Northern Territory. Since the 1980s, the density of C. porosus in upstream, freshwater reaches of the Daly and Roper rivers has increased, as has the inland extent of C. porosus on the Daly River. Although C. porosus was not detected in spotlight surveys of the Victoria River, helicopter survey and anecdotal records indicate that C. porosus was present after 1989. In all, 52.1% of the crocodiles sighted in spotlight surveys were 2.1–3.4 m long. Distribution records show that C. porosus occurs up to 235 km inland and at elevations of up to 126 m above sea level. The potential distribution of C. porosus is likely to be similar to that of barramundi (Lates calcarifer), a readily identifiable diadromous fish that must spawn in estuarine waters and occurs at elevations of up to 178 m above sea level. Because the density and inland extent of C. porosus in freshwater rivers is likely to increase, it is recommended that: (1) programs communicating crocodile awareness use the linkage between the presence of barramundi and the potential presence of C. porosus; (2) that crocodile warning signs be erected in upstream areas within the potential range of C. porosus; (3) that research be conducted on developing techniques to detect and exclude C. porosus from swimming areas; and (4) that widespread systematic surveys be undertaken to document the inland extent of C. porosus.
23
Martínez, M. L., L. J. Chapman, and B. B. Rees. "Population variation in hypoxic responses of the cichlid Pseudocrenilabrus multicolor victoriae." Canadian Journal of Zoology 87, no. 2 (February 2009): 188–94. http://dx.doi.org/10.1139/z09-002.
Full textAbstract:
F1 offspring of the African cichlid Pseudocrenilabrus multicolor victoriae Seegers, 1990 from swamp (low oxygen) and lake (high oxygen) origin were raised under normoxia and submitted to hypoxia acclimation (0.8 ± 0.4 mg·L–1) and normoxia acclimation (7.4 ± 0.3 mg·L–1) for 4 weeks. Haematocrit and lactate dehydrogenase (LDH) specific activities in the liver, white skeletal muscle, heart, and brain were measured. For haematocrit and LDH activities of liver, muscle, and heart, the response to acclimation depended upon population of origin. In general, fish from the swamp population showed a more “typical” hypoxic response (increased haematocrit and LDH activities), whereas fish from the lake population either did not respond or showed the opposite response. The results suggest that populations of P. m. victoriae sampled from habitats with diverse oxygen regimes differ in their physiological and biochemical responses to hypoxia.
24
Dinelka Thilakarathne and Gayan Hirimuthugoda. "Can the Sri Lankan endemic-endangered fish Labeo fisheri (Teleostei: Cyprinidae) adapt to a new habitat?" Journal of Threatened Taxa 14, no. 8 (August 26, 2022): 21579–87. http://dx.doi.org/10.11609/jott.7621.14.8.21579-21587.
Full textAbstract:
Labeo fisheri is an endemic and endangered freshwater fish of Sri Lanka. Mainly restricted to the upper reaches of the Mahaweli River basin, it has been previously reported living in deep rapids and among large rocks and boulders. An accidental record of a Labeo fisheri specimen from Victoria Reservoir led us to further study this habitat during the period from January to August 2017. This study was carried out to confirm the presence of a population of Labeo fisheri within the Victoria Reservoir and report its new habitat type in deep stagnant waters. We further investigated the food habits by analyzing the gut contents of L. fisheri in the Victoria Reservoir. Seven individuals were recorded from fishermen’s gill net catch in three fish landing sites along Victoria Reservoir, with an average total length of 24.80 ± 4.30 cm, average standard length of 19.70 ± 3.86 cm and average body weight of 197.69 ± 107.12 g. Based on gut content analysis, only phytoplankton, especially diatoms and cyanobacteria, were found in the gut of L. fisheri. This new population is facing the direct threat of fishing. Effective conservation measures are doubtful, since a fishery is well established in the Victoria Reservoir and the fishing gear used is not species-specific. More research is necessary to understand the population dynamics of L. fisheri in the Victoria Reservoir. In order to conserve it at this locality, community-based conservation measures are recommended.
25
Hamer, Paul A., Gregory P. Jenkins, and Bronwyn M. Gillanders. "Chemical tags in otoliths indicate the importance of local and distant settlement areas to populations of a temperate sparid, Pagrus auratus." Canadian Journal of Fisheries and Aquatic Sciences 62, no. 3 (March 1, 2005): 623–30. http://dx.doi.org/10.1139/f04-221.
Full textAbstract:
Understanding geographic origins of fish is essential to the management of fisheries and protection of critical juvenile habitats. We used natural chemical tags (Mn, Sr, and Ba), characterized from otoliths of 0+ snapper (Pagrus auratus) (approximately 13 months postsettlement), to determine the origins of 1- and 2-year-old (subadult) fish about to recruit to the Victorian fishery. We sampled subadults from eight areas across 700 km of coastline and within the major Victorian fishery, Port Phillip Bay. Maximum likelihood analyses indicated for both cohorts that most subadults in Port Phillip Bay and a significant proportion from west Victorian coastal waters had settled within Port Phillip Bay. The contribution of the Port Phillip Bay settlement area to coastal populations, however, decreased with distance to the west, varied between cohorts, and was negligible at locations over 200 km to the east of the bay. Comparison of elemental tags between 0+ fish of known settlement origin and the subadults indicated that unknown settlement areas may have contributed recruitment to one of the cohorts. These results have highlighted the importance of local settlement areas to sustaining the major Victorian fishery, but small juveniles can migrate large distances from this settlement area and contribute to coastal populations.
26
Gotanda, K. M., E. E. Reardon, S. M. C. Murphy, and L. J. Chapman. "Critical swim speed and fast-start response in the African cichlid Pseudocrenilabrus multicolor victoriae: convergent performance in divergent oxygen regimes." Canadian Journal of Zoology 90, no. 5 (May 2012): 545–54. http://dx.doi.org/10.1139/z2012-019.
Full textAbstract:
Dissolved oxygen (DO) can be a strong predictor of intraspecific variation in morphology and physiology in fishes. In the African cichlid Pseudocrenilabrus multicolor victoriae Seegers, 1990, fish reared under low DO develop larger gills, deeper bodies, and larger, wider heads than full siblings reared under high DO, which could influence swim performance. In this study, we compared critical swim speed (Ucrit) and fast-start swimming in F1-generation fish from two field populations (one high and one low DO) of P. m. victoriae reared under high or low DO. There was no difference in Ucrit between populations or rearing treatments. However, females exhibited a lower Ucrit than males. In fast-start trials, low-DO-reared fish reacted faster (lower response latency) and used double bends more often than high-DO-reared fish, but there was no difference in maximum velocity or acceleration. Low-DO-reared fish might compensate for morphological differences by using double bends to achieve similar performance as high-DO siblings. These results suggest that divergent morphotypes of P. m. victoriae are capable of achieving the same level of performance under their home DO condition and highlights the importance of developmental plasticity in facilitating adaptive response to alternative environments.
27
Mameri, Daniel, Corina van Kammen, Ton G. G. Groothuis, Ole Seehausen, and Martine E. Maan. "Visual adaptation and microhabitat choice in Lake Victoria cichlid fish." Royal Society Open Science 6, no. 3 (March 2019): 181876. http://dx.doi.org/10.1098/rsos.181876.
Full textAbstract:
When different genotypes choose different habitats to better match their phenotypes, genetic differentiation within a population may be promoted. Mating within those habitats may subsequently contribute to reproductive isolation. In cichlid fish, visual adaptation to alternative visual environments is hypothesized to contribute to speciation. Here, we investigated whether variation in visual sensitivity causes different visual habitat preferences, using two closely related cichlid species that occur at different but overlapping water depths in Lake Victoria and that differ in visual perception ( Pundamilia spp.). In addition to species differences, we explored potential effects of visual plasticity, by rearing fish in two different light conditions: broad-spectrum (mimicking shallow water) and red-shifted (mimicking deeper waters). Contrary to expectations, fish did not prefer the light environment that mimicked their typical natural habitat. Instead, we found an overall preference for the broad-spectrum environment. We also found a transient influence of the rearing condition, indicating that the assessment of microhabitat preference requires repeated testing to control for familiarity effects. Together, our results show that cichlid fish exert visual habitat preference but do not support straightforward visual habitat matching.
28
Osure, George Owiti, Albert Getabu, Christopher Mulanda Aura, Reuben Omondi, and Evans Basweti. "Population parameters and exploitation rates of four commercial fish species of Awach Kibuon River: Towards sustainable management of riverine fisheries of the Lake Victoria Basin." International Journal of Fisheries and Aquatic Studies 10, no. 6 (November 1, 2022): 87–92. http://dx.doi.org/10.22271/fish.2022.v10.i6b.2751.
Full text
29
Bassa, Samuel, Albert Getabu, Erick Ogello, Anthony Taabu, Mark Olokotum, Herbert Nakiyende, Musinguzi Laban, et al. "Saving the endangered Native Victoria Tilapia, Oreochromis variabilis Boulenger (1906), in Upper Victoria Nile." Uganda Journal of Agricultural Sciences 20, no. 1 (December 1, 2021): 29–43. http://dx.doi.org/10.4314/ujas.v20i1.2.
Full textAbstract:
This study investigated the catch estimates, mortality, growth, food and feeding habits, and water parameters of Oreochromis variabilis in Upper Victoria Nile (UVN) from 2008 to 2019. Catch rates ranged 0.32±0.08 to 3.42±1.13 kg, boat-1, day-1 with the length-weight relationship indicating Isometric growth. Growth parameters obtained were L∞=36.75, K=0.44 yr-1, t0=-0.4540, tmax=6.4years, ØL=2.774, ØW=-0.301. Total mortality (Z) was 1.74yr-1, natural mortality (M) =0.95yr-1 using riverine surface temperature (RST) of 26oC giving a fishing mortality F of 0.79 yr-1 and exploitation ratio (E) of 0.4504 showing that growth parameters concurs with annual estimates and yield (F=6.589; P±=0.05). Catch estimates correlated with water parameters that indicated a significant difference. Mortality parameters showed that the fishery could be experiencing exploitation pressure. Although growth rates revealed that the fish is a long-lived species, if managed properly, its population could recover. Therefore, culturing the species and restocking in rivers and lakes in which this specie was not observed in the East African region are recommended.
30
Bezault, Etienne, Salome Mwaiko, and Ole Seehausen. "POPULATION GENOMIC TESTS OF MODELS OF ADAPTIVE RADIATION IN LAKE VICTORIA REGION CICHLID FISH." Evolution 65, no. 12 (September 1, 2011): 3381–97. http://dx.doi.org/10.1111/j.1558-5646.2011.01417.x.
Full text
31
Bassa, Samuel. "Effects of Exploitation Pressures and River Damming on the Population Structure of Elephant Snout Fish (Mormyrus Kannume) Forsskal 1775: A Case Study on the Upper Victoria Nile." Uganda Journal of Agricultural Sciences 18, no. 1 (March 15, 2018): 15–31. http://dx.doi.org/10.4314/ujas.v18i1.2.
Full textAbstract:
The Elephant snout fish (Mormyrus kannume) Forsskal (1775) is one of the riverine fish species that was previously important for the River Nile riparian people as food and income. The fish is currently exploited mainly as bait for the Nile perch. This study was conducted from 2008 to 2016 and focused on catch rates, value, size structure, maturity status, and feeding habits of M. kannume. Annual catch estimates were made in order to evaluate the exploitation rate of the fish. Results revealed clear fluctuations in catches with a general increase in revenue from 1,200 (000) US$ to 8,600 (000) US$. With comparison to available literature, the fish exhibited a smaller size at maturity and smaller mean focal length (L50 for males and females were 25.2 and 28.2 cm; mean fork length of (25.9±0.32 cm). The observed changes could be due to increased fishing effort along with gear changes from gillnets to basket traps. Therefore the exploitation rate of the Elephant snout fish in the upper Victoria Nile may be unsustainable. Keywords: Bait; exploitation; Nile perch
32
Gooley, GJ. "Validation of the use of Otoliths to determine the ate and growth of Murray Cod, Maccullochella peelii (Mitchell) (Percichthyidae), in Lake Charlegrark, Western Victoria." Marine and Freshwater Research 43, no. 5 (1992): 1091. http://dx.doi.org/10.1071/mf9921091.
Full textAbstract:
The age and growth of Murray cod, Maccullochella peelii, in Lake Charlegrark, western Victoria, were determined by using otoliths from fish sampled by beach-seine and gill-net, or caught by anglers, between August 1978 and August 1982. Annulus formation was validated up to 11 + years by several methods. Otoliths were examined from hatchery-bred fish of known age (up to 4+ years) that had been stocked into local farm ponds. Analysis of incremental growth for all fish sampled from the lake indicated that the mean edge-growth ratio was lowest, and the percentage of otoliths with an annulus at the edge was highest, in October. A nominal birth date of 1 October was designated for the population to enable calculation of the absolute age for each fish. Age-composition data for those fish taken by gill-net and by anglers (up to 21 + years) revealed modal progression of strong year classes (1970 to 1973 inclusive) during the sampling period. Length-frequency data for those fish taken by beach-seine (up to 3 + years) revealed modal progression, on a seasonal basis, of two relatively strong year classes (1978 and 1979) during the sampling period. A von Bertalanffy growth curve was fitted to length and age data for all fish collected in the lake (no sex difference, P>O.05), and growth parameters were estimated for the population (L∞ = 695 mm). This curve did not adequately describe the growth of fish older than 11 + years because the majority of sampled fish (98.3%) were aged 11 + years or younger. The length-weight relationship for the population was determined by using data from all fish collected in the lake (no sex difference, P>0.05).
33
Gray, Suzanne M., Laura H. McDonnell, Fabio G. Cinquemani, and Lauren J. Chapman. "As clear as mud: Turbidity induces behavioral changes in the African cichlid Pseudocrenilabrus multicolor." Current Zoology 58, no. 1 (February 1, 2012): 146–57. http://dx.doi.org/10.1093/czoolo/58.1.146.
Full textAbstract:
Abstract Aquatic biodiversity is being lost at an unprecedented rate. One factor driving this loss is increased turbidity, an environmental stressor that can impose behavioral, morphological, and/or physiological costs on fishes. Here we describe the behavioral response of a widespread African cichlid, Pseudocrenilabrus multicolor victoriae, to turbidity. We used a split-brood rearing design to test if F1 offspring reared in turbid water, originating from river (turbid) and swamp (clear) populations, behave differently than full-sibs reared in clear water. We examined two facets of behavior: (1) behaviors of fish in full sib groups, including activity level and social dynamics collected during the rearing period; and (2) male aggressive behavior directed at potential male competitors after fish had reached maturity; this was done in an experimental set-up independent of the rearing aquaria. Regardless of population of origin, fish reared in turbid water were marginally less active and performed fewer social behaviors than those reared in clear water. On the other hand, when tested against a competitor in turbid water, males performed more aggressive behaviors, regardless of population of origin or rearing environment. Our results suggest a plastic behavioral response to turbidity that may allow P. multicolor to persist over a range of turbidity levels in nature by decreasing activity and general social behaviors and intensifying reproductive behaviors to ensure reproductive success.
34
Faragher, RA. "Growth and age validation of Rainbow Trout, Oncorhynchus mykiss (Walbaum)' in Lake Eucumbene, NSW." Marine and Freshwater Research 43, no. 5 (1992): 1033. http://dx.doi.org/10.1071/mf9921033.
Full textAbstract:
Growth rates of finclipped rainbow trout (Oncorhynchus mykiss) released into Lake Eucumbene, New South Wales, at an age of 0+ years were examined for each year between 1986 and 1988. Traps and nets yielded significant numbers of marked fish for validation of age estimation and length backcalculation from scale reading. Poor recognition of the marks by anglers was confirmed, indicating that survival of the fish was higher than was implied by angling returns. The diffuse nature of the second annulus in scales provided initial difficulty in ageing, particularly because of a similarly diffuse false check formed during the second year. Care was required in separating the annuli after asymptotic growth was reached (3 years), Growth rates in Lake Eucumbene were comparable with those found in studies in Tasmania and Victoria. Back-calculated lengths were in agreement with those from fish of known ages. The presence of finclipped fish aged 2 + and 3 + years in a spawning population confirmed that stocked fish contributed to the spawning stocks. The study reconfirms the importance of validation of ageing techniques in fisheries investigations.
35
Hughes, Julian M., John Stewart, Bronwyn M. Gillanders, Damian Collins, and Iain M. Suthers. "Relationship between otolith chemistry and age in a widespread pelagic teleost Arripis trutta: influence of adult movements on stock structure and implications for management." Marine and Freshwater Research 67, no. 2 (2016): 224. http://dx.doi.org/10.1071/mf14247.
Full textAbstract:
This study investigated how the stock structure of Arripis trutta is influenced by the movement of adult fish. Five-year-old fish were sampled from four regions in south-east Australia encompassing ~1500km of coastline. Transverse otolith sections were analysed using laser-ablation inductively coupled plasma-mass spectrometry, providing age-related elemental profiles. Multivariate analyses showed that for most age groups, the elemental fingerprint of northern New South Wales (NSW) fish was significantly different from those of the other locations. Northern NSW fish also had a different fingerprint from those of all other locations for the first part of the fish’s life. These results indicate that most A. trutta originate in southern NSW, Victoria and Tasmania and move progressively northward with increasing age. Some recruitment occurs in northern NSW but these fish may not mix with immigrants from further south until they are more than 5 years old. When assessed with the strong latitudinal age gradient of the population, these data are consistent with a single, panmictic stock. The data also highlight the utility of otolith transect analysis in understanding the influence of age-related movements on stock structure and appropriate spatial management of exploited fish species.
36
Stelkens, Rike B., Michele E. R. Pierotti, Domino A. Joyce, Alan M. Smith, Inke van der Sluijs, and Ole Seehausen. "Disruptive sexual selection on male nuptial coloration in an experimental hybrid population of cichlid fish." Philosophical Transactions of the Royal Society B: Biological Sciences 363, no. 1505 (June 3, 2008): 2861–70. http://dx.doi.org/10.1098/rstb.2008.0049.
Full textAbstract:
Theory suggests that genetic polymorphisms in female mating preferences may cause disruptive selection on male traits, facilitating phenotypic differentiation despite gene flow, as in reinforcement or other models of speciation with gene flow. Very little experimental data have been published to test the assumptions regarding the genetics of mate choice that such theory relies on. We generated a population segregating for female mating preferences and male colour dissociated from other species differences by breeding hybrids between species of the cichlid fish genus Pundamilia . We measured male mating success as a function of male colour. First, we demonstrate that non-hybrid females of both species use male nuptial coloration for choosing mates, but with inversed preferences. Second, we show that variation in female mating preferences in an F 2 hybrid population generates a quadratic fitness function for male coloration suggestive of disruptive selection: intermediate males obtained fewer matings than males at either extreme of the colour range. If the genetics of female mate choice in Pundamilia are representative for those in other species of Lake Victoria cichlid fish, it may help explain the origin and maintenance of phenotypic diversity despite some gene flow.
37
ABILA, ROMULUS, MARTA BARLUENGA, JOHANNES ENGELKEN, AXEL MEYER, and WALTER SALZBURGER. "Population-structure and genetic diversity in a haplochromine fish cichlid of a satellite lake of Lake Victoria." Molecular Ecology 13, no. 9 (September 2004): 2589–602. http://dx.doi.org/10.1111/j.1365-294x.2004.02270.x.
Full text
38
Svardal, Hannes, Fu Xiang Quah, Milan Malinsky, Benjamin P. Ngatunga, Eric A. Miska, Walter Salzburger, Martin J. Genner, George F. Turner, and Richard Durbin. "Ancestral Hybridization Facilitated Species Diversification in the Lake Malawi Cichlid Fish Adaptive Radiation." Molecular Biology and Evolution 37, no. 4 (December 14, 2019): 1100–1113. http://dx.doi.org/10.1093/molbev/msz294.
Full textAbstract:
Abstract The adaptive radiation of cichlid fishes in East African Lake Malawi encompasses over 500 species that are believed to have evolved within the last 800,000 years from a common founder population. It has been proposed that hybridization between ancestral lineages can provide the genetic raw material to fuel such exceptionally high diversification rates, and evidence for this has recently been presented for the Lake Victoria region cichlid superflock. Here, we report that Lake Malawi cichlid genomes also show evidence of hybridization between two lineages that split 3–4 Ma, today represented by Lake Victoria cichlids and the riverine Astatotilapia sp. “ruaha blue.” The two ancestries in Malawi cichlid genomes are present in large blocks of several kilobases, but there is little variation in this pattern between Malawi cichlid species, suggesting that the large-scale mosaic structure of the genomes was largely established prior to the radiation. Nevertheless, tens of thousands of polymorphic variants apparently derived from the hybridization are interspersed in the genomes. These loci show a striking excess of differentiation across ecological subgroups in the Lake Malawi cichlid assemblage, and parental alleles sort differentially into benthic and pelagic Malawi cichlid lineages, consistent with strong differential selection on these loci during species divergence. Furthermore, these loci are enriched for genes involved in immune response and vision, including opsin genes previously identified as important for speciation. Our results reinforce the role of ancestral hybridization in explosive diversification by demonstrating its significance in one of the largest recent vertebrate adaptive radiations.
39
Knuckey, Ian A., and K. P. Sivakumaran. "Reproductive characteristics and per-recruit analyses of blue warehou (Seriolella brama): implications for the South East Fishery of Australia." Marine and Freshwater Research 52, no. 4 (2001): 575. http://dx.doi.org/10.1071/mf00022.
Full textAbstract:
Monthly samples of commercial catches of S. brama were collected between May 1996 and December 1997 in three regions of the fishery:off the east coast of Victoria; eastern Tasmania; and western Bass Strait. Sex ratio, gonadosomatic index, macroscopic and histological development, size at maturity and fecundity were estimated and combined with data on growth and mortality to perform per-recruit analyses. The main spawning period was during winter–spring and there was evidence of spawning in each of the three regions. Blue warehou reach maturity at 30–40 cm fork length. They have a determinate annual fecundity and spawn around three batches of eggs during a season. Eggs-per-recruit analyses revealed maximum egg production at ~40 cm (4–5 years) in an unfished population. Gill-net fishing, which targets fish >45 cm, was less likely to affect the relative eggs-per-recruit in a population than trawl fishing, which catches a wider range of smaller fish. These results are discussed in light of the current management arrangements in the fishery and will be used in models to assess the effect of fishing on the long-term sustainability of the blue warehou.
40
Mpomwenda, Veronica, Tumi Tómasson, Jón Geir Pétursson, Anthony Taabu-Munyaho, Herbert Nakiyende, and Daði Mar Kristófersson. "Adaptation Strategies to a Changing Resource Base: Case of the Gillnet Nile Perch Fishery on Lake Victoria in Uganda." Sustainability 14, no. 4 (February 18, 2022): 2376. http://dx.doi.org/10.3390/su14042376.
Full textAbstract:
Sustainable management of fisheries has proven to be a daunting exercise for Lake Victoria. Exploitation patterns in the fishery are driven by fishers who adopt different strategies as a response to changing economic, management, socio-economic, and resource conditions. Fisheries managers, however, seldom consider these changes in management policies. The aim of the study, therefore, was to evaluate the adaptation strategies of the Nile perch gillnet fishers on Lake Victoria in Uganda using 8-year catch and effort data collected in the period from 2005 to 2015. Trends of the selected effort and catch variables in the study period identified two adaptive fishing strategies by gillnet fishers on the lake. The first group, the paddled fishermen whose gillnet use varied in the first half of the study, diverted to harvesting juvenile Nile perch by using smaller, mesh sizes, monofilament nets and gillnets of less depth in the second half of the study. Motorized fishers, on the other hand, maintained their mesh size, using multifilament gillnets, however, they increased the depth of their nets in the second half of the study period to maintain their targeted fish size. Fishers on Lake Victoria adapted strategies to cope with their constraints and opportunities based on the Nile perch population structure and their economic needs. It is important for fishery managers to consider that the fishers are an integral part of the fisheries ecosystems, and considering their behavior in management decisions will aid in devising adaptive policies for sustainable resource use and sustainable livelihood development of the fishers’ communities.
41
Gardner, J. L., and M. Serena. "Observations on Activity Patterns, Population and Den Characteristics of The Water Rat Hydromys chrysogaster Along Badger Creek, Victoria." Australian Mammalogy 18, no. 1 (1995): 71. http://dx.doi.org/10.1071/am95071.
Full textAbstract:
The Water Rat Hydromys chrysogaster is Australia's largest amphibious rodent, occupying freshwater rivers, lakes, and coastal and estuarine habitats throughout the continent (Watts and Aslin 1981). Little is known of the species' social organisation or use of space in the wild although Harris (1978) suggested that adults might be intrasexually aggressive. The home ranges of all sex and age classes overlap to some extent but home ranges of adults of the same sex appear to overlap less (Harris 1978). Adult males occupy the largest home ranges which overlap those of one or more females. In captivity individuals kept in groups form hierarchies in which only the dominant females usually breed successfully (Olsen 1982). Fighting occurs primarily among males, with the highest incidence of injuries observed at the beginning of the main September-March breeding season (Olsen 1980, 1982). The results of trapping studies indicate that population density may vary considerably, with the greatest numbers of animals typically occupying man-modified habitats such as irrigation channels or fish farms (McNally 1960, Watts and Aslin 1981, Smales 1984). Aggressive behaviour appears to be related to pelage colour (phenotype) and population density; the higher the density the greater the number of injured individuals (Olsen 1980).
42
van der Sluijs, Inke, Ole Seehausen, Tom J. M. Van Dooren, and Jacques J. M. van Alphen. "No evidence for a genetic association between female mating preference and male secondary sexual trait in a Lake Victoria cichlid fish." Current Zoology 56, no. 1 (February 1, 2010): 57–64. http://dx.doi.org/10.1093/czoolo/56.1.57.
Full textAbstract:
Abstract Sexual selection by female mating preference for male nuptial coloration has been suggested as a driving force in the rapid speciation of Lake Victoria cichlid fish. This process could have been facilitated or accelerated by genetic associations between female preference loci and male coloration loci. Preferences, as well as coloration, are heritable traits and are probably determined by more than one gene. However, little is known about potential genetic associations between these traits. In turbid water, we found a population that is variable in male nuptial coloration from blue to yellow to red. Males at the extreme ends of the phenotype distribution resemble a reproductively isolated species pair in clear water that has diverged into one species with blue-grey males and one species with bright red males. Females of the turbid water population vary in mating preference coinciding with the male phenotype distribution. For the current study, these females were mated to blue males. We measured the coloration of the sires and male offspring. Parents-offspring regression showed that the sires did not affect male offspring coloration, which confirms earlier findings that the blue species breeds true. In contrast, male offspring coloration was determined by the identity of the dams, which suggests that there is heritable variation in male color genes between females. However, we found that mating preferences of the dams were not correlated with male offspring coloration. Thus, there is no evidence for strong genetic linkage between mating preference and the preferred trait in this population.
43
Paterson, John. "Water Management and Recreational Values; Some Cases in Victoria, Australia." Water Science and Technology 21, no. 2 (February 1, 1989): 1–12. http://dx.doi.org/10.2166/wst.1989.0021.
Full textAbstract:
The growing recognition of recreational and amenity demands on water systems introduces a multitude of issues, many of them complex, to the established tasks of water quality management and water management generally. Victorian case studies are presented. They (1) illustrate the range and diversity of situations that can arise in managing competition and enhancing compatibility between traditional water supply objectives and recreational demands. (2) Fluctuation of storage levels, essential to storage operations, detract from recreational value. Recreational and tourism demands upon Lake Hume have grown to threaten traditional operating flexibility. (3) Mokoan is another such instance, but with its supply function in a state of flux, Lake Mokoan provides more scope for a shift in the balance. (4) Salinity management has become an issue in the management of lakes and wetlands when water supply interests and environmental/recreation interests respectively have different perspectives on salt disposal. (5) Recreational use of town supply sources has long been a vexed issue, although marked shifts in the attitudues of many supply authorities have occurred in recent years. (6) Eutrophication of lakes and estuaries raises difficult issues of responsibility and scientific uncertainty, and the water management connection may be tenuous but will attract public attention. (7) The water body attributes valued by specialised recreational interests require definition in terms that water managers can deal with using routine techniques of systems analysis and evaluation. (8) The demands of the fish population and anglers introduce a new perspective in river management and perceptions of instream values are changing markedly. (9) Direct costs of recreational services supplied by water authorities are not fully accounted: allocation choices and fiscal incidence will emerge as issues of significance. (10) These case studies raise only a fraction of the total range of matters that will, in the years to come, tax the technology and political skills of governments and management.
44
Gooley, GJ, TA Anderson, and P. Appleford. "Aspects of the reproductive cycle and gonadal development of Murray cod, Maccullochella peelii peelii (Mitchell) (Percicthidae), in Lake Charlegrark and adjacent farm ponds, Victoria, Australia." Marine and Freshwater Research 46, no. 4 (1995): 723. http://dx.doi.org/10.1071/mf9950723.
Full textAbstract:
The gonadal development of Murray cod, Maccullochella peelii peelii, in Lake Charlegrark, Victoria, and adjacent farm ponds was evaluated. Gonadosomatic index, macroscopic classification and histological analysis were used to determine the age at first maturity and the gonadal development in this introduced population. There is a marked difference between the sexes in the size at first maturity, with females maturing at approximately 6 years of age and 2000 g in weight and males maturing at 3-4 years and 700 g. Gonadosomatic index data indicate that spawning occurs around November. Ovarian development in this species follows a pattern similar to that in a number of other teleosts. Testes have a lobular structure. Macroscopic evaluation of ovaries provided a good indication of the stage of the development of the gonad. However, the presence of spermatozoa throughout the year in the gonads of mature male fish makes the macroscopic evaluation of testicular development less reliable. Three cod, approximately 1% of the population, contained gonads with both ovarian and testicular tissue.
45
Dove, A. D. M., and A. S. Fletcher. "The distribution of the introduced tapeworm Bothriocephalus acheilognathi in Australian freshwater fishes." Journal of Helminthology 74, no. 2 (June 2000): 121–27. http://dx.doi.org/10.1017/s0022149x00000160.
Full textAbstract:
AbstractNative and exotic fishes were collected from 29 sites across coastal and inland New South Wales, Queensland and Victoria, using a range of techniques, to infer the distribution of Bothriocephalus acheilognathi (Cestoda: Pseudophyllidea) and the host species in which it occurs. The distribution of B. acheilognathi was determined by that of its principal host, carp, Cyprinuscarpio; it did not occur at sites where carp were not present. The parasite was recorded from all native fish species where the sample size exceeded 30 and which were collected sympatrically with carp: Hypseleotris klunzingeri, Hypseleotris sp. 4, Hypseleotris sp. 5, Phylipnodon grandiceps and Retropinna semoni. Bothriocephalus acheilognathi was also recorded from the exotic fishes Gambusia holbrooki and Carassiusauratus. Hypseleotris sp. 4, Hypseleotris sp. 5, P. grandiceps, R. semoni and C. auratus are new host records. The parasite was not recorded from any sites in coastal drainages. The only carp population examined from a coastal drainage (Albert River, south-east Queensland) was also free of infection; those fish had a parasite fauna distinct from that of carp in inland drainages and may represent a separate introduction event. Bothriocephalus acheilognathi has apparently spread along with its carp hosts and is so far restricted to the Murray-Darling Basin. The low host specificity of this parasite is cause for concern given the threatened or endangered nature of some Australian native freshwater fish species. A revised list of definitive hosts of B. acheilognathiis presented.
46
Roos, Nanna, Md Abdul Wahab, Mostafa Ali Reza Hossain, and Shakuntala Haraksingh Thilsted. "Linking Human Nutrition and Fisheries: Incorporating Micronutrient-Dense, Small Indigenous Fish Species in Carp Polyculture Production in Bangladesh." Food and Nutrition Bulletin 28, no. 2_suppl2 (June 2007): S280—S293. http://dx.doi.org/10.1177/15648265070282s207.
Full textAbstract:
Background Fish and fisheries are important for the livelihoods, food, and income of the rural population in Bangladesh. Increased rice production and changing agricultural patterns have resulted in a large decline in inland fisheries. Implementation of carp pond polyculture has been very successful, whereas little focus has been given to the commonly consumed small indigenous fish species, some of which are rich in vitamin A and minerals, such as calcium, iron, and zinc, and are an integral part of the rural diet. Objective The overall objective of the research and capacity-building activities described in this paper is to increase the production, accessibility, and intake of nutrient-dense small indigenous fish species, in particular mola ( Amblypharyngodon mola), in order to combat micronutrient deficiencies. The large contribution from small indigenous fish species to recommended intakes of vitamin A and calcium and the perception that mola is good for or protects the eyes have been well documented. Methods An integrated approach was conducted jointly by Bangladeshi and Danish institutions, linking human nutrition and fisheries. Activities included food-consumption surveys, laboratory analyses of commonly consumed fish species, production trials of carp–mola pond polyculture, teaching, training, and dissemination of the results. Results No decline in carp production and thus in income was found with the inclusion of mola, and increased intake of mola has the potential to combat micronutrient deficiencies. Teaching and training of graduates and field staff have led to increased awareness of the role of small indigenous fish species for good nutrition and resulted in the promotion of carp–mola pond polyculture and research in small indigenous fish species. The decline in accessibility, increase in price, and decrease in intake of small indigenous fish species by the rural poor, as well as the increased intake of silver carp ( Hypophthalmichthys molitrix), the most commonly cultured fish species, which is poor in micronutrients and not preferred for consumption, are being addressed, and some measures taken by inland fisheries management have been discussed. Conclusions The successful linking of human nutrition and fisheries to address micronutrient deficiencies has relevance for other countries with rich fisheries resources, such as Cambodia and countries in the Lake Victoria region of Africa.
47
Reardon, E. E., and L. J. Chapman. "Fish embryo and juvenile size under hypoxia in the mouth-brooding African cichlid Pseudocrenilabrus multicolor." Current Zoology 58, no. 3 (June 1, 2012): 401–12. http://dx.doi.org/10.1093/czoolo/58.3.401.
Full textAbstract:
Abstract We used a field survey and a laboratory rearing experiment to (a) examine response (size and survival) to life-long hypoxia in offspring of the African maternal mouth-brooding cichlid Pseudocrenilabrus multicolor victoriae (Seegers) and (b) explore the degree to which developmental response can be environmentally-induced. Embryo size metrics were quantified in 9 field populations across a range of dissolved oxygen (DO) concentrations. In the laboratory, first generation (F1) broods of low-DO origin were reared under high or low DO. Brooding period was quantified for the mothers; and egg size, egg metabolic rate and juvenile size-at-release were quantified in their (F2) offspring. The F2 offspring were split and grown for 3 months post-release under high or low DO, and juvenile size and survival were quantified. In the field survey, across stages, embryos from low-DO field populations were shorter and weighed less than embryos from high-DO populations. In the laboratory experiment, F2 eggs and juveniles-at-release from mother’s mouth did not differ in mass, length, survival regardless of development DO environment. However, juveniles diverged in size after leaving mother’s mouth, exhibiting smaller size when grown under low DO. Size differences in embryo size across field populations and divergence in embryo size after release from the mother’s mouth support predictions for smaller body size under hypoxia. There was no evidence for negative effects on survival of juveniles after 3 months. Brooding period was 16% shorter in females reared under low DO suggesting that hypoxia may accelerate embryo de velopment. This work provides insights into how bearer fishes respond to hypoxic stress relative to fishes with no post-spawning parental care; a shorter brooding interval and smaller body size may provide an optimal solution to parent and embryo survival under hypoxia in brooding fishes.
48
Dawson, D. R., and W. M. Koster. "Habitat use and movements of Australian grayling (Prototroctes maraena) in a Victorian coastal stream." Marine and Freshwater Research 69, no. 8 (2018): 1259. http://dx.doi.org/10.1071/mf17198.
Full textAbstract:
Riverine fishes are among the most imperilled fauna in the world; however, for many species, there is little or no understanding of their ecological requirements. The Australian grayling (Prototroctes maraena) is a small diadromous fish endemic to rivers in south-eastern Australia that has declined considerably in range and abundance and is listed as threatened nationally. To improve understanding of the species’ movement ecology and to inform the development of conservation management actions, we examined the day-to-day movements and habitat use of Australian grayling (n=7) over 8 weeks by using radio-telemetry. Tagged individuals of Australian grayling typically occupied restricted (i.e. tens to hundreds of metres) reaches of stream, and were mostly located in moderate- to fast-flowing habitats (i.e. glide or run), although, at night, use of slower-flowing habitats (i.e. pools) increased. They also undertook longer-distance downstream movements during a period of increased streamflow. Incorporation of such information into management strategies has the potential to improve our capacity to maintain or re-instate the conditions required to conserve and restore Australian grayling populations.
49
Svensson, Ola, Katie Woodhouse, Cock van Oosterhout, Alan Smith, George F. Turner, and Ole Seehausen. "The genetics of mate preferences in hybrids between two young and sympatric Lake Victoria cichlid species." Proceedings of the Royal Society B: Biological Sciences 284, no. 1849 (February 22, 2017): 20162332. http://dx.doi.org/10.1098/rspb.2016.2332.
Full textAbstract:
The genetic architecture of mate preferences is likely to affect significant evolutionary processes, including speciation and hybridization. Here, we investigate laboratory hybrids between a pair of sympatric Lake Victoria cichlid fish species that appear to have recently evolved from a hybrid population between similar predecessor species. The species demonstrate strong assortative mating in the laboratory, associated with divergent male breeding coloration (red dorsum versus blue). We show in a common garden experiment, using DNA-based paternity testing, that the strong female mate preferences among males of the two species are fully recovered in a large fraction of their F2 hybrid generation. Individual hybrid females often demonstrated consistent preferences in multiple mate choice trials (more than or equal to five) across a year or more. This result suggests that female mate preference is influenced by relatively few major genes or genomic regions. These preferences were not changed by experience of a successful spawning event with a male of the non-preferred species in a no-choice single-male trial. We found no evidence for imprinting in the F2 hybrids, although the F1 hybrid females may have been imprinted on their mothers. We discuss this nearly Mendelian inheritance of consistent innate mate preferences in the context of speciation theory.
50
Greaves, Peter. "Regional differences in the mid-Victorian diet and their impact on health." JRSM Open 9, no. 3 (March 2018): 205427041775186. http://dx.doi.org/10.1177/2054270417751866.
Full textAbstract:
Summary The aim of this study was to examine the impact of regional diets on the health of the poor in mid-Victorian Britain. Contemporary surveys of regional diets and living condition were reviewed. This information was compared with mortality data from Britain over the same period. Although there was an overall improvement in life expectancy during the latter part of the 19th century, there were large regional differences in lifestyle, diet and mortality rates. Dietary surveys showed that the poor labouring population in isolated rural areas of England, in the mainland and islands of Scotland and in the west of Ireland enjoyed the most nutritious diets. These regions also showed the lowest mortality rates in Britain. This was not simply the result of better sanitation and less mortality from food and waterborne infections but also fewer deaths from pulmonary tuberculosis, which is typically associated with better nutrition. These more isolated regions where a peasant-style culture provided abundant locally produced cheap foodstuffs such as potatoes, vegetables, whole grains, and milk and fish, were in the process of disappearing in the face of increasing urbanisation. This was to the detriment of many rural poor during the latter half of the century. Conversely, increasing urbanisation, with its improved transport links, brought greater availability and diversity of foods to many others. It was this that that led to an improved nutrition and life expectancy for the majority in urbanising Britain, despite the detrimental effects of increasing food refinement.