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1. Length-based assessment for mackerel icefish (Champsocephalus gunnari) at South Georgia

   Georgia Abstract / Description:  The current CCAMLR assessment method for mackerel icefish ... (Champsocephalus gunnari) in Subarea 48.3 employs the CCAMLR mixture analysis program (CMIX) and generalised yield ... the given harvest control rule to set a two-year total allowable catch (TAC). One issue is the ... accurate identification of age cohorts from the survey data. In this paper a length-based approach is ... define numbers-at-age in the population. Assuming a closed population (i.e. with no recruit- ment) the ... which there are P times P) to generate the transition matrix Γ. Note also that no error distribution ... estimated numbers-at-length are assumed to be the total closed population abundance (i.e. there is no ... no systematic differences between results from the proposed length-based method and the current ...

   Science Journal Paper : CCAMLR Science, Volume 17 (CCAMLR Science, Volume 17) : 129–137 : Auteur(s): Hillary, R.M., C.T.T. Edwards, R.E. Mitchell and D.J. Agnew

2. Marine debris and fishing gear associated with seabirds at sub-Antarctic Marion island, 1996/97 and 1997/98: in relation to longline fishing activity

   debris found in association with seabirds at sub-Antarctic Marion Island for the period May 1996 to April ... 1998 is reported. Standardised searches and incidental finds show a large increase between the 1996/97 ... and the 1997/98 field seasons. Fishing gear increased at a rate 10 times higher than 'other' ... found. Prior to this study only three hooks (all from the southern bluefin tuna longline industry) had ... and longline fishing industry. As we collected all debris (i.e. there was no bias in the type of ... association with seabirds at sub-Antarctic Marion Island for the period May 1996 to April 1998 is reported ... . Standardised searches and incidental finds show a large increase between the 1996/97 and the 1997/98 field ... from the southern bluefin tuna longline industry) had been found in association with seabird nests at ...

   Science Journal Paper : CCAMLR Science, Volume 6 (CCAMLR Science, Volume 6) : 85–96 : Auteur(s): Nel, D.C. and J.L. Nel

3. Catch per unit effort and proportional recruitment indices from Japanese krill fishery data in Subarea 48.1

   . CPUE (catch/towing volume) in the Livingston Island area showed a decreasing trend during the study ... period. The use of different fishing strategies in response to a demand for higher product quality and a ... general decrease in krill density in the study area were considered as possible reasons for this. On the ... other hand, CPUE in the Elephant Island area showed greater interannual variation without any trend ... ), but no significant trend in the Elephant Island area (T = -0.200, n = 11, p = 0.39). DISCUSSION ... no clear trend was observed in the search for krill aggregations before deploying Elephant Island ... . CPUE (catch/towing volume) in the Livingston Island area showed a decreasing trend during the study ... period. The use of different fishing strategies in response to a demand for higher product quality and a ...

   Science Journal Paper : CCAMLR Science, Volume 4 (CCAMLR Science, Volume 4) : 47–63 : Auteur(s): Kawaguchi, S., T. Ichii and M. Naganobu

4. Calibration of an acoustic echo-integration system in a deep tank, with system gain comparisons over standard sphere material, water temperature and time

   outlines the theory and procedures for calibrating an echo integration acoustic system with a standard ... sphere. It presents the results of an extensive calibration of a Simrad EK500 scientific echosounder with ... length (0.1, 0.3 and 1.0 ms), target depth (0.8 to 7.5 m), and time (149 days). The total range in TS ... gain, including the effects of temperature, standard sphere and time, is 2.9 dB. Gain values calibrated ... independent of orientation, and no additional electronic equipment is required (Blue, 1984). Furthermore, the ... be performed with no effect from the water column boundaries so that only spherical waves reflecting ... . Therefore, if no data were collected exactly on axis, the nearest data to the axis were used after being ... parameter alone, can be no better than ±0.5 dB. At greater ranges, the biases are proportionally larger ...

   Science Journal Paper : Selected Scientific Papers, SC-CAMLR-SSP/9 (Selected Scientific Papers, SC-CAMLR-SSP/9) : 127–144 : Auteur(s): Demer, D.A. and R.P. Hewitt

5. Variations in condition indices of mackerel icefish at South Georgia from 1972 to 1997

   1997 Abstract / Description:  Mackerel icefish (Champsocephalus gunnari) are widespread on the South ... Georgia shelf, Antarctica, and have been fished commercially since the early 1970s. They are known to feed ... predominantly on krill. An index of condition which uses the ratio of the measured total mass to the estimated ... mass is shown to provide a good indicator of local krill density. The index is likely to be little ... the breeding site. The foraging trip and diet parameters integrate over these same scales but in ... fur seal pup weight in 1973, a year when there were no reports of krill scarcity, to that on the ... penguins on the shore of Cumberland Bay, South Georgia, in March 1978. In 1978/79, when penguin breeding ... density. There were no krill density estimates during 1977 and 1978, so we infer that the changes in ...

   Science Journal Paper : CCAMLR Science, Volume 8 (CCAMLR Science, Volume 8) : 119–132 : Auteur(s): Everson, I. and K.-H. Kock

6. Can we use discriminant function analysis to sex penguins prior to calculating an index of a morphometric characteristic?

   discriminant analysis can be used to determine the sex of individuals, it is only able to correctly sex a ... difference between the real mean characteristic for a sex, and the apparent mean derived by sexing the birds ... using discriminant analysis. When discriminant functions are able to correctly determine the sex of ... birds with greater than 80% success, the difference between the true and apparent mean is likely to be ... males and females, and these often overlap. Whilst discriminant analysis can be used to determine the ... normal distributions are used to show that there is a difference between the real mean characteristic ... for a sex, and the apparent mean derived by sexing the birds using discriminant analysis. When ... discriminant functions are able to correctly determine the sex of birds with greater than 80% success, the ...

   Science Journal Paper : Selected Scientific Papers, SC-CAMLR-SSP/9 (Selected Scientific Papers, SC-CAMLR-SSP/9) : 259–272 : Auteur(s): Agnew, D.J.

7. Assessments of by-catch in trawl fisheries at Heard and McDonald Islands

   / Description:  This paper assesses the potential for the commercial trawl fisheries in the Heard Island area ... (Statistical Division 58.5.2) to significantly affect, in the long term, spawning biomass of three taxa caught ... skates). The long-term annual yield for each of the three taxa was estimated using the generalised yield ... model (GYM) used by the CCAMLR Working Group on Fish Stock Assessment (WG-FSA). Input data included ... 5.18 to 5.26). This was necessary because no information was available on the actual magnitude of ... the probability of depletion below 0.2 of the median pre-exploitation spawning biomass be no greater ... fishing site and at times making operations very difficult. In the C. gunnari fishery, C. rhinoceratus ... by-catch is no greater than 5% of the total catch, however, would exclude many areas from ...

   Science Journal Paper : CCAMLR Science, Volume 5 (CCAMLR Science, Volume 5) : 231–243 : Auteur(s): Constable, A.J., R. Williams and W.K. de la Mare

8. Midwater trawl catchability in relation to krill and possible ways of assessing gross catch

   the basis of data obtained from AtlantNIRO expeditions from 1983 to 1990 in the Scotia Sea. A ... methodology was developed for and applied to determining the rate of krill filtration through the trawl rope ... and netting and also the probability that krill will come into contact with various parts of the net ... as it passes through the trawl sides. Studies were based on the results of 250 hauls made with a 72 ... . Frolov** Abstract Research into midwater trawl catchability rates was carried out on the basis of ... data obtained from AtlantNIRO expeditions from 1983 to 1990 in the Scotia Sea. A methodology was ... developed for and applied to determining the rate of krill filtration through the trawl rope and netting ... and also the probability that krill will come into contact with various parts of the net as it passes ...

   Science Journal Paper : Selected Scientific Papers, SC-CAMLR-SSP/7 (Selected Scientific Papers, SC-CAMLR-SSP/7) : 87–113 : Auteur(s): Zimarev, Yu.V., S.M. Kasatkina and Yu.P. Frolov

9. An index of per capita recruitment

   recruitment (PCR) is proposed such that where R 1 is the proportion of age-l animals sampled in year y and M ... is the post-recruit mortality rate. The intent of the index is to facilitate investigation of ... reproductive success and the factors postulated to affect it. The formulation of PCR is based on the ... animals spawn; (iii) a representative sample of the population is available; and (iv) the proportion of ... that the ratio of PCR to R/S would be 0.317 if half of age-2 animals spawn and to 0.266 if no age-2 ... R/S showed no central tendency with lower values more common than higher values. The distribution ... equilibrium spawning population but has no effect on the ratio of PCR and R/S. (iv) Increasing the rate at ... where R1 is the proportion of age-l animals sampled in year y and M is the post-recruit mortality rate ...

   Science Journal Paper : CCAMLR Science, Volume 7 (CCAMLR Science, Volume 7) : 179–196 : Auteur(s): Hewitt, R

10. Krill biomass in Area 48 and Area 58: recalculations of FIBEX data

    / Description:  FIBEX acoustic and length frequency data held in the BIOMASS database were used to provide ... estimates of mean density and biomass for the Indian Ocean sector and the West Atlantic sector as well as ... estimates were calculated using the target strength relationships used at the original FIBEX acoustic ... workshop. Estimates for the different areas were also calculated using the target strength relationships of ... ., 1986 - p. 46), but no information was available for the Nella Dan. 2.1. 2 Acoustic Data Data were ... 41.4 mm for the cruise. Since no length frequency data were available for Kaiyo Maru, this TS value ... held in the BIOMASS database were used to provide estimates of mean density and biomass for the ... Indian Ocean sector and the West Atlantic sector as well as for FAO Statistical Area 41, and CCAMLR ...

    Science Journal Paper : Selected Scientific Papers, SC-CAMLR-SSP/9 (Selected Scientific Papers, SC-CAMLR-SSP/9) : 157–181 : Auteur(s): Trathan, P.N., D.J. Agnew, D.G.M. Miller, J.L. Watkins, I. Everson, M.R. Thorley, E. Murphy, A.W.A. Murray and C. Goss

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