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Estimation of natural mortality using catch-at-age and aged mark-recapture data: a multi-cohort simulation study comparing estimation for a model based on the Baranov equations versus a new mortality equation.
functional form of selectivity was correctly specified in the BODE model, both models gave close to unbiased ... selectivity function, the bias and imprecision in estimates of M increased by no more than 2% for the CCODE ... number of recaptures-at-age and model the population numbersat- age by annual difference equations ... of 500 000. Simulations which passed catch-at-age numbers to the estimation algorithm after ... error were also carried out for each model in order to investigate the effect on estimation of M ... form of selectivity was correctly specified in the BODE model, both models gave close to unbiased and ... selectivity function, the bias and imprecision in estimates of M increased by no more than 2% for the CCODE ... model parameters and then calcu- lating allowable catch under the set of decision rules applied in ...
Science Journal Paper : CCAMLR Science, Volume 18 (CCAMLR Science, Volume 18) : 1–27 : Autor(es): Candy, S.G.
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The effects of monitoring procedures on Adélie penguins
Paper Title: The effects of monitoring procedures on Adélie penguins Abstract / Description: The ... effects of flipper bands, implanted tags, gastric lavage and external instrument attachment on the ... , Antarctica. The return rates of birds carrying bands and/or implanted electronic transponders were compared ... to investigate the contribution of bands to bird mortality and to determine rates of band and tag ... winter. The attachment of satellite tracking devices during the incubation period resulted in increased ... Adklie penguins (Pygoscelis ndeliae) in order to determine the range of natural variation present in ... backs of penguins causes a significant increase in the drag of swimming birds which, in turn ... 'E) in Eastern Antarctica through the development of an automated weighing and identification ...
Science Journal Paper : CCAMLR Science, Volume 1 (CCAMLR Science, Volume 1) : 155–164 : Autor(es): Clarke, J. and K. Kerry
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Estimating the impact of depredation by killer whales and sperm whales on longline fishing for toothfish (Dissostichus eleginoides) around South Georgia
Paper Title: Estimating the impact of depredation by killer whales and sperm whales on longline ... data collected on longliners between 2003 and 2009 were analysed to look at the levels of depredation ... 3.8% and sperm whales on 17.7% of lines. Killer whales appear in pod sizes normally of 4 to 10 animals ... , and often appear to actively seek out fishing vessels and ‘strip’ the line of a large number of ... the start of the season with the sightings becoming fewer towards the end of the season in August ... sperm whales were seen but significantly lower in the presence of killer whales, suggesting that sperm ... information from both fishers and scientific observers suggest an increase in the numbers of cetaceans and ... in the overall levels of depredation which will affect both the fishing industry and fishery ...
Science Journal Paper : CCAMLR Science, Volume 17 (CCAMLR Science, Volume 17) : 163–178 : Autor(es): Moir Clark, J. and D.J. Agnew
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On the intensity of sampling krill trawl catches
uses actual krill length-frequency data in an attempt to address the problem of the determination of ... be discerned (e.g., length-with-age). At present, and in the interests of both statistical rigour and ... Paper Title: On the intensity of sampling krill trawl catches Abstract / Description: This paper ... . The possible effect of two other factors (within-trawl variability and sample decomposition) which may ... differences in mean length with area as a function of sample size is to be derived by increasing the length ... most suited for the detection of a 2 mm difference in mean length between the two areas. A similar ... the projected sample sizes required for the detection of specific differences in mean length between ... measuredllocation (Le., 50, 150 or 50 in one size class). 3.3 Analysis of Samples With Time The mean lengths of ...
Science Journal Paper : Selected Scientific Papers, SC-CAMLR-SSP/7 (Selected Scientific Papers, SC-CAMLR-SSP/7) : 29–48 : Autor(es): Miller, D.G.M.
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Results of the CCAMLR Antarctic fish otoliths/scales/bones exchange system
. antarcticum. Agreement between otoliths and scales of individual N. gibberifrons was in the order of 50 ... Paper Title: Results of the CCAMLR Antarctic fish otoliths/scales/bones exchange system Abstract ... / Description: An exchange system was established among Members of CCAMLR to compare age determinations for the ... same species among different laboratories. Four species were included in the exchange: Notothenia ... , Notothenia gibberifrons and PJeuragramma antarcticum. The level of agreement in age determination was ... between otoliths and scales of individual N. gibberifrons was in the order of 50%. There was little ... recommendation of the CCAMLR Fish Age Determination Workshop held in Moscow from 14 to 19 July 1986 (SC-CAMLR ... and Argentina. Laboratories of the following Members took part in the exchange: USSR, Poland, German ...
Science Journal Paper : Selected Scientific Papers, SC-CAMLR-SSP/6 (Selected Scientific Papers, SC-CAMLR-SSP/6) : 197–226 : Autor(es): Kock, K.-H.
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Vertical migrations of mackerel icefish (Champsocephalus gunnari) on the South Georgia shelf
commercial concentrations of C. gunnari in years of high abundance of the species (1982/83, 1983/84 and 1986 ... considered in the paper. A distinct pattern of daily vertical migrations of C. gunnari was observed on the ... Paper Title: Vertical migrations of mackerel icefish (Champsocephalus gunnari) on the South ... Georgia shelf Abstract / Description: High values of coefficient of variation resulting from the ... and nototheniids in shelf waters of the South Georgia by means of trawl surveys. The assessment ... call for improvement of techniques in order to obtain reliable estimates. The objective of the ... evening hours and the gradual increase of catches in the morning indicates that fish migrate more rapidly ... highest. Therefore we did not observe any substantial differences in catches according to the time of day ...
Science Journal Paper : Selected Scientific Papers, SC-CAMLR-SSP/8 (Selected Scientific Papers, SC-CAMLR-SSP/8) : 3–14 : Autor(es): Frolkina, J.A. and V.I. Shlibanov
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Some comments on the procedure for testing estimators of krill abundance which utilise survey data
provide an encouraging improvement in fits to the distribution of inter-swarm distances observed on the ... Paper Title: Some comments on the procedure for testing estimators of krill abundance which ... computer generation of krill distribution patterns, which are compatible with existing information on the ... utilise survey data Abstract / Description: Since krill distributional data do show evidence of spatial ... provide an encouraging improvement in fits to the distribution of inter-swarm distances observed on the ... estimation from surveys of marine resources is to place a set of transects at random in the area of interest ... . The density estimate from each transect is then treated as an independent estimate of the density in ... survey. In the case of krill, it has been suggested (Foote and Stefansson, 1991) that estimation ...
Science Journal Paper : Selected Scientific Papers, SC-CAMLR-SSP/8 (Selected Scientific Papers, SC-CAMLR-SSP/8) : 191–205 : Autor(es): Butterworth, D.S., D.L. Borchers and D.G.M. Miller
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Physical oceanographic setting of the Siedlecki January 1987, South Shetland Island data set
data set Abstract / Description: In the vicinity of the northern tip of the Antarctic Peninsula, the ... Paper Title: Physical oceanographic setting of the Siedlecki January 1987, South Shetland Island ... water from the Pacific Ocean. A series of fronts form which are collectively referred to as the Weddell ... continental margin water, advected into the region along the extreme western edge of the Weddell Gyre. It is ... into the region along the extreme western edge of the Weddell Gyre. It is relatively cold and low in ... to these changes in the habitat. Our challenge is to understand the causes of environmental ... -ice coupled system is in itself exceedingly complex. Added to this is the life cycle of krill, which ... Antarctic Peninsula, meet the warmer waters carried in from the Pacific Ocean. It is a region of strong ...
Science Journal Paper : Selected Scientific Papers, SC-CAMLR-SSP/5 – Part II (Selected Scientific Papers, SC-CAMLR-SSP/5 – Part II) : 161-184 : Autor(es): Gordon, A.L.
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An alternative method for estimating the level of illegal fishing using simulated scaling methods on detected effort
performs better in the case of zero detections and can potentially better handle the evasion of detection ... fishing (in the simulation datasets) for a given estimated level of fishing is very large. This range of ... Paper Title: An alternative method for estimating the level of illegal fishing using simulated ... effort is put forward. The results from this new method are similar to those of the Agnew and Kirkwood ... zero illegal fi shing. The new method performs better in the case of zero detections and can ... prevention/detection problem, in which the greater the number of detections for a given level of illegal fi ... degree of legitimacy. However, the range of actual fi shing (in the simulation datasets) for a given ... Fest is the estimate of illegal fi shing in days, Obsnum is the number of observations of illegal fi ...
Science Journal Paper : CCAMLR Science, Volume 12 (CCAMLR Science, Volume 12) : 143–161 : Autor(es): Ball, I
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A simple approach for calculating the potential yield of krill from biomass survey results
Paper Title: A simple approach for calculating the potential yield of krill from biomass survey ... results Abstract / Description: Estimates are calculated for the parameter λ in the yield equation Y = λ ... MB 0 for a krill fishery in which both the fishery and krill growth are seasonal. The criterion used ... for the calculations is that the probability that the krill spawning biomass drops below 20% of its ... along these lines. 2. METHODS The mathematical detail of the calculations carried out is given in ... of zero growth. Much of the fishing of krill off Antarctica is concentrated in the three summer ... estimate Bo which is to be used in equation (1) is considered to be made in the middle of the season (Le ... (survey sampling) estimation error has been made in this analysis [the 11 term in equation (A.9) of ...
Science Journal Paper : Selected Scientific Papers, SC-CAMLR-SSP/8 (Selected Scientific Papers, SC-CAMLR-SSP/8) : 207–217 : Autor(es): Butterworth, D.S., A.E. Punt and M. Basson