| Einträge |
| Autor |
Labelle, M. |
| Titel |
A likelihood method for estimating Pacific salmon escapement based on fence counts and mark-recapture data |
Typ |
Zeitschrift, Artikel |
| Jahr |
1994 |
Publikation  |
Can. J. Fish. Aquat. Sci. |
Kurztitel der Zeitschrift |
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| Band |
51 |
Ausgabe |
3 |
Seiten |
552-566 |
| Schlüsselwörter |
capt-recapt, methode, ML, modell, statistik, simulation |
| Zusammenfassung |
Pacific salmon (Oncorhynchus spp.) escapements in natural streams are often determined by conducting fence counts in conjunction with mark-recapture operations. Typical field conditions are characterized by protracted floods, undetected immigration, variation in sampling rates, mortality during the census periods, small sample sizes, and few successive recaptures. Closed population models tend to overestimate escapement under such conditions, and traditional open population models cannot always be relied on due to the lack of sufficient data. A likelihood-based estimation method was specifically designed for such conditions. A distinguishing feature of this model is that individual recapture histories are not required for parameter estimation. The model is also structured to incorporate ancillary data in the estimation process to improve the precision and accuracy of the estimates. The model is described in detail, and suggestions are made to facilitate its application. |
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nein |
| Rufnummer |
468 |
Signatur |
2269 |
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| Autor |
McGarvey, R. |
| Titel |
An age-structured open-access fishery model |
Typ |
Zeitschrift, Artikel |
| Jahr |
1994 |
Publikation |
Can. J. Fish. Aquat. Sci. |
Kurztitel der Zeitschrift |
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| Band |
51 |
Ausgabe |
4 |
Seiten |
900-912 |
| Schlüsselwörter |
modell, statistik, population, dynamik, algorithmus |
| Zusammenfassung |
A dynamic model for open-access fisheries is presented. In addition to density dependence in recruitment and fishing effort changing in proportion to the level of profit fishermen earn which characterizes previous open-access models, it incorporates full age structure for the fish stock, lognormal environmental recruitment variability, and gear selectivity. The predator-prey cycling solution of the original Schaefer dynamic model, and subsequent open-access models, persists for these model extensions. Density dependence in recruitment induces greater global stability. Environmental recruitment variability, common in marine populations, is destabilizing in the neighborhood of the open-access equilibrium. Approximating model steady states of effort and catch by the corresponding averages from data time series underlies a new algorithm of parameter evaluation, applied here to an open-access model of the Georges Bank sea scallop (Placopecten magellanicus) fishery. |
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nein |
| Rufnummer |
469 |
Signatur |
2270 |
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| Autor |
Kenchington, E. L.; Full, W. E. |
| Titel |
Fourier analysis of sea scallop (Placopecten magellanicus) shell in determining population structure |
Typ |
Zeitschrift, Artikel |
| Jahr |
1994 |
Publikation |
Can. J. Fish. Aquat. Sci. |
Kurztitel der Zeitschrift |
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| Band |
51 |
Ausgabe |
2 |
Seiten |
348-356 |
| Schlüsselwörter |
population, fourier, statistik, methode, modell, wachstum, muscheln |
| Zusammenfassung |
Sea scallops (Placopecten magellanicus) were sampled from each of four scallop beds: the northeast peak of Georges Bank, Western Bank, St. Pierre Bank, and the Bay of Fundy near Digby, N.S. The outlines of scallop top shells were captured by video imagery using a semiautomated approach. Fourier shape descriptors were calculated and analyzed. Age and year-class effects were shown to be important factors influencing scallop shell shape. Allometric effects on Fourier harmonics also have a significant influence on shell shape in this species. Comparisons of Fourier harmonics between scallop beds separated by age and sampling year, and corrected for allometry, revealed significant differences in the majority of harmonic numbers. |
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nein |
| Rufnummer |
472 |
Signatur |
2273 |
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| Autor |
Walters, C. |
| Titel |
Estimation of historical stock sizes and recruitment anomalies from relative abundance time series |
Typ |
Zeitschrift, Artikel |
| Jahr |
1995 |
Publikation |
Can. J. Fish. Aquat. Sci. J. Can. Sci. Halieut. Aquat |
Kurztitel der Zeitschrift |
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| Band |
52 |
Ausgabe |
7 |
Seiten |
1523-1534 |
| Schlüsselwörter |
stock-assessment; approximation-; anomalies-; recruitment-; abundance-; growth-; survival-; algorithms-; fishery-management; marine-fisheries |
| Zusammenfassung |
Often only simple relative abundance time series and basic growth and (or) survival estimates are available for assessing impacts of fishing and environmental factors. Assessment then involves fitting production models to the series, while forcing the model with observed catch or effort series. A key uncertainty in this approach is how to deal with recruitment variations due to factors other than stock size. A dynamic programming algorithm can be used to compute maximum likelihood estimates of the recruitment anomaly sequence, given prior knowledge of growth parameters, the natural survival rate, and proportion of the variation in the relative abundance index that is due to abundance measurement errors. |
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Zu bestellen |
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1779 |
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Wang, Y. G.; Thomas, M. R. |
| Titel |
Accounting for individual variability in the von Bertalanffy growth model |
Typ |
Zeitschrift, Artikel |
| Jahr |
1995 |
Publikation |
Can. J. Fish. Aquat. Sci. J. Can. Sci. Halieut. Aquat |
Kurztitel der Zeitschrift |
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52 |
Ausgabe |
7 |
Seiten |
1368-1375 |
| Schlüsselwörter |
Fisch, Statistik, Methode, Vergleich, Wachstum, Bertalanffy, Faben |
| Zusammenfassung |
Estimation of von Bertalanffy growth parameters has received considerable attention in fisheries research. Since Sainsbury much of this research effort has centered on accounting for individual variability in the growth parameters. In this paper we demonstrate that, in analysis of tagging data, Sainsbury's method and its derivatives do not, in general, satisfactorily account for individual variability in growth, leading to inconsistent parameter estimates (the bias does not tend to zero as sample size increases to infinity). The bias arises because these methods do not use appropriate conditional expectations as a basis for estimation. |
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CSIRO IPP&P Biometrics Unit, CSIRO Div. Fish., Box 120, Cleveland, Queensland 4163, Australia |
Geprüft |
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| Rufnummer |
524 |
Signatur |
2323 |
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Myers, R. A.; Cadigan, N. G. |
| Titel |
Statistical analysis of catch-at-age data with correlated errors |
Typ |
Zeitschrift, Artikel |
| Jahr |
1995 |
Publikation |
Can. J. Fish. Aquat. Sci. J. Can. Sci. Halieut. Aquat |
Kurztitel der Zeitschrift |
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52 |
Ausgabe |
6 |
Seiten |
1265-1273 |
| Schlüsselwörter |
Fisch, Fischerei, Statistik, Wachstum, Mortalität, VPA, Population, Mathematik, Modell |
| Zusammenfassung |
The statistical model used is extended to estimate abundance from commercial catch-at-age data for many of the major commercial fish species in the world. The model combines commercial catch-at-age data and research survey estimates of fish abundance; extends the model to allow correlated errors among ages within a year for the survey estimates of fish abundance. Method is formulated for modeling the fishing mortality on the oldest ages of the fish caught. Estimates are obtained using maximum likelihood. The level of correlation among ages is sufficiently large to produce large biases in the standard methods for some stocks. The statistical model that includes correlated errors greatly reduces bias and increases efficiency if the correlation in the estimation error is large. |
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Dep. Fish. Oceans, Sci. Branch, Box 5667, St. John's, NF A1C 5X1, Canada |
Geprüft |
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| Rufnummer |
528 |
Signatur |
2327 |
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Hoenig, J. M.; Morgan, M. J.; Brown, C. A. |
| Titel |
Analysing differences between two age determination methods by tests of symmetry |
Typ |
Zeitschrift, Artikel |
| Jahr |
1995 |
Publikation |
Can. J. Fish. Aquat. Sci. J. Can. Sci. Halieut. Aquat |
Kurztitel der Zeitschrift |
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| Band |
52 |
Ausgabe |
2 |
Seiten |
364-368 |
| Schlüsselwörter |
Altersbestimmung, Fischerei, Statistik, Methode |
| Zusammenfassung |
A common problem in fisheries science is the comparison of two methods for obtaining ages of individual animals. The authors suggest that if the overall level of agreement is low between two ageing methods used on the same sample of fish, then one can use a test of symmetry to look for evidence of systematic disagreement. A chi super(2) test is used to determine if the number of fish assigned age i from method 1 and age j from method 2 differs significantly from the number of fish assigned age j from method 1 and age i from method 2. Such a test can also be used to determine the range of nominal ages over which two methods appear to give comparable results. |
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Dep. Fish. and Oceans, P.O. Box 5667, St. John's, NF A1C 5X1, Canada |
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| Rufnummer |
532 |
Signatur |
2331 |
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Angermeier, P. L.; Smogor, R. A. |
| Titel |
Estimating number of species and relative abundances in stream-fish communities: Effects of sampling effort and discontinuous spatial distributions |
Typ |
Zeitschrift, Artikel |
| Jahr |
1995 |
Publikation |
Can. J. Fish. Aquat. Sci. J. Can. Sci. Halieut. Aquat |
Kurztitel der Zeitschrift |
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52 |
Ausgabe |
5 |
Seiten |
936-949 |
| Schlüsselwörter |
Fisch, Fließgewässer, Habitat, Verbreitung |
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The authors sampled fishes and measured microhabitat in series of contiguous habitat units (riffles, runs, pools) in three Virginia streams. Monte Carlo simulations were used to construct hypothetical series of habitat units, then examined how number of species, similarity in relative abundances, and number of microhabitats accumulated with increasing number of habitat units (i.e., sampling effort). The curves indicated that 90% of the species present were usually found by sampling 5 to 14 habitat units (stream length of 22-67 stream widths). Estimates of species relative abundances required less sampling effort for a given accuracy than estimates of number of species. Rates of species accumulation (with effort) varied among streams and reflected discontinuity in species distributions among habitat units. Most discontinuity seemed to be due to low population density rather than to habitat selectivity. Results from an Illinois stream corroborated our findings from Virginia, and suggested that greater sampling effort is needed to characterize fish community structure in more homogeneous stream reaches. |
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Natl. Biol. Serv., Virginia Coop. Fish Wildl. Res. Unit, Virginia Polytech. Inst., Blacksburg, VA 24061-0321, USA |
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nein |
| Rufnummer |
620 |
Signatur |
2414 |
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Riffel, M.; Schreiber, A. |
| Titel |
Morphometric differentiation in populations of the Central European sculpin Cottus gobio L., a fish with deeply divergent genetic lineages |
Typ |
Zeitschrift, Artikel |
| Jahr |
1998 |
Publikation |
Can. J. Zool. |
Kurztitel der Zeitschrift |
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76 |
Ausgabe |
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Seiten |
876-885 |
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Fisch, Population, Genetik, Groppe, Mühlkoppe, Cottus gobio, Verbreitung |
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| Rufnummer |
179 |
Signatur |
2068 |
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Mertz, G.; Myers, R. A. |
| Titel |
An extended cohort analysis: incorporating the effect of seasonal catches |
Typ |
Zeitschrift, Artikel |
| Jahr |
1996 |
Publikation |
Canadian Journal of Fisheries and Aquatic Sciences |
Kurztitel der Zeitschrift |
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53 |
Ausgabe |
1 |
Seiten |
159-163 |
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vpa, statistik, methode, modell, mathematik, fischerei, mortalität |
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| Rufnummer |
502 |
Signatur |
2302 |
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