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  • 1
    Electronic Resource
    Electronic Resource
    Application of semi-quantitative electrofishing to juvenile salmonid stock surveys (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 45 (1994), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A semi-quantitative electrofishing technique is described, which has applications for assessing distribution and densities of 0+ salmonids in streams. Linear regressions of logarithmically-transformed data satisfactorily described the relationship between numbers of 0+ Atlantic salmon (Salmo salar L.) and 0+ brown trout (Salmo trutta L.) captured in a standard 5 min fishing and quantitative population estimates obtained using a commonly used method. Applications of the semi-quantitative technique to management are discussed and a categorization system proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1994.tb01293.x
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  • 2
    Electronic Resource
    Electronic Resource
    Application of a fry (0+;) abundance index, based on semi-quantitative electrofishing, to predict Atlantic salmon smolt runs in the River Bush, Northern Ireland (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 47 (1995), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: An abundance index for 0+ Atlantic salmon was based on semi-quantitative electrofishing estimates at 137 sites in typical juvenile habitat throughout the River Bush (N. Ireland). 0 + abundance was linearly related to total smolt numbers migrating through a downstream trap in subsequent years (r2= 0.716, P〈0.001), suggesting a high degree of predictive ability. This predictive ability decreased as smolt age increased, suggesting influence of density-independent mortality. Potential application of the technique to estimate smolt production from rivers having no trapping facilities is discussed, together with sources of variability potentially affecting estimates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1995.tb01877.x
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Allozyme variation in Atlantic salmon from the British Isles: associations with geography and the environment (2005)
    Oxford, UK; Malden, USA : Blackwell Science Ltd
    Journal of fish biology 67 (2005), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Data on geographical variation in allele frequencies at enzyme coding loci in Atlantic salmon from the British Isles were collated from published and unpublished sources. Statistically significant differences in allele frequencies were found among samples both within and among river systems, suggesting that the Atlantic salmon in the British Isles is not a panmictic population and that even within major river systems it cannot be treated as a single genetic stock for fisheries management purposes. Although there was some evidence of regional differences in the frequency of some rare alleles, most single-locus variation did not show strong geographic patterns, with the exception of the AAT-4* locus at which allele frequencies had a significant latitudinal cline. There was some evidence for the existence of genetically-distinct celtic and boreal races of Atlantic salmon in the British Isles as previously has been suggested. Multiple regression analyses revealed associations between genetic variation and local environmental conditions (i.e. between variation at MEP-2* and both temperature and local river gradient), providing additional evidence for adaptive population divergence in the species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.0022-1112.2005.00845.x
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  • 4
    Electronic Resource
    Electronic Resource
    Experimental production of triploid brown trout, Salmo trutta L., using heat shock (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Aquaculture research 20 (1989), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract. This study was designed to investigate the potential of heat shock to produce triploidy in brown trout, Salmo trutta L., and to develop a methodof routinely identifying triploids in this species. Triploids were produced in all heat-shocked batches and were identified by the size of their erythrocyte nucleus, which had a volume ratio of 1:1-57 relative to diploid controls. Cytogenetic and flow cytometric analyses confirmed that trout with the larger nuclei were triploid. Heat shock of 28°Cof 10 min duration initiated 5-15 min post-insemination produced high rates of triploidy in experimental batches (88-2-100%), later shocks at 20-25 min producing lower rates (down to 60%). Reproducibilicy of tripioid rates was generally good, a maximum difference between replicates of 21.9% being observed, the majority of differences being considerably less. The highest triploid yield was produced with a heat shock of 28°C for 10 min initiated at 10 or 20 min post-insemination, the difference between replicates being due to variability in survival to hatch. Survival to hatch was generally lower in groups having higher rates of tripioidy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2109.1989.tb00362.x
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  • 5
    Electronic Resource
    Electronic Resource
    An investigation into the reproducibility of triploid brown trout, Salmo trutta L., production using heat shock (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Aquaculture research 26 (1995), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: A single heat shock of 28°C for 10 min, applied 15 min after water activation to five different batches of brown trout, Salmo trutta L., ova and replicated within one batch produced triploid rates ranging from 22% to 100% and variable survival to hatch ranging from 9.4% to 47.9%. Variability was greater among batches than among replicates. In general, the treatment reduced survival to hatch by 50%. The range of triploid yields obtained from a single heat shock regime is discussed in terms of potential advantages to aquaculture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2109.1995.tb00861.x
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  • 6
    Electronic Resource
    Electronic Resource
    Maintenance of genetic variation in hatchery stocks of Atlantic salmon, Salmo salar L.: experiences from the River Bush, Northern Ireland (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Aquaculture research 25 (1994), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract. An examination of biochemical-genetic variation at seven polymorphic loci was carried out among five year classes of wild Atlantic salmon, Salar L., in the R. Bush and in a hatchery strain derived from the wild population. Within some of the year classes, gene frequencies at several loci differed significantly between wild and artificially reared salmon. Highly significant temporal variation in gene frequencies was detected among successive year classes of the hatchery strain, while this was less significant among the wild salmon. Samples of wild salmon taken as 0+ and 1 + parr in the river showed no significant temporal variability in allelic frequencies. Heterozygosity levels among the wild and hatchery-reared salmon were comparable, averaging 0·185 and 0·176 respectively. The genetic variability of the artificially reared salmon is discussed in relation to numbers of broodstock and breeding regime used at the hatchery.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2109.1994.tb00703.x
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  • 7
    Electronic Resource
    Electronic Resource
    Electrophoretic examination of the population structure of brown trout, Salmo trutta L., from the Lough Neagh catchment, Northern Ireland (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 28 (1986), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Samples of brown trout, Salmo trutia L., from 34 locations throughout the Lough Neagh system in north-east Ireland were electrophoretically examined for genetic variation at 28 enzyme loci. Patterns of allelic variation at 12 polymorphic loci indicated the existence of genetic differentiation within as well as among several river systems, suggesting the existence of multiple brown trout populations. Significant gene frequency differences were detected over distances as little as 3 km, demonstrating the propensity of this species for microgeographic genetic differentiation. This was confirmed by a hierarchical analysis of genetic variance, some 35% of among-sample variance being distributed within tributaries. Within Lough Neagh itself significant genetic differentiation was detected between two morphotypes (dollaghan and salmon-trout) and for one of these (dollaghan) among samples from different years and from different areas of the lough. This suggests the existence of genetically differentiated subpopulations of originating from separate river catchments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1986.tb05183.x
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  • 8
    Electronic Resource
    Electronic Resource
    The relationship between a summer fry (0+) abundance index, derived from semi-quantitative electrofishing, and egg deposition of Atlantic salmon, in the River Bush, Northern Ireland (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 47 (1995), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Atlantic salmon survival in the R. Bush (N. Ireland) from egg to summer 0+ was inversely density-dependent on egg deposition (P〈0.05). A stock-recruitment relationship derived from egg deposition and summer 0+ abundance index data was compared to that derived from adult and smolt counts based on total trapping. Fitted Ricker curves indicated maximum recruitment at around 2.35 million eggs and 2.46 million eggs for 0+ index and smolt count methods, respectively. Salmon 0+ abundance index data from semi-quantitative electrofishing could be obtained with relatively little effort, and used to derive whole-river stock-recruitment relationships on rivers where only adult count or some other estimator of parental stock is available. The derivation and expression of spawning targets from stock/recruitment relationships is discussed with reference to the R. Bush data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1995.tb06029.x
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  • 9
    Electronic Resource
    Electronic Resource
    Amount and distribution of biochemical-genetic variation among wild populations and a hatchery stock of Atlantic salmon, Salmo salar L., from north-east Ireland (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 35 (1989), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Tissue samples from a total of 617 Atlantic salmon from seven locations in north-east Ireland were electrophoretically examined for genetic variation at 28 enzyme loci. Patterns of allelic variation at eight polymorphic loci indicated the existence of genetic differentiation within, as well as among, river systems. This suggests the presence of localized genetically differentiated populations of salmon in N. Ireland. Temporal variation in allelic frequencies was tested among three year classes of wild R. Bush salmon and found to be insignificant compared to the spatial variation. Examination of equivalent year classes of R. Bush hatchery-reared salmon displayed significant temporal variation at five loci, and significant departures from Hardy-Weinberg equilibrium at two loci. Heterozygosity was not reduced in the Bush hatchery population (mean 4.3%) compared to the wild populations sampled (range, 2.9-5.4%; mean, 4.2%). These results are discussed in relation to management of wild populations and maintenance of hatchery stocks.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1989.tb03018.x
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  • 10
    Electronic Resource
    Electronic Resource
    Observations on the food and feeding of the angler-fish, Lophim piscatorius L., in the northern Irish Sea (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 27 (1985), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Stomach contents of angler-fish caught monthly throughout the year were examined. Stomach fullness data suggested that maximum feeding activity occurred during the autumn/winter period. Gadoids, in particular whiting and Norway pout, and also Nephrops were the main identifiable prey items. A wide range of other species contributed to the remainder of the diet. Size-related differences in stomach contents were observed, Nephrops, cod and whiting being favoured by adult angler-fish. Seasonal variability in the dietary occurrence of herring and Nephrops was noted, apparently related to differences in availability rather than selective feeding by angler-fish.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1985.tb03210.x
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