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1. A preliminary investigation of the possible effects of rhizocephalan parasitism on the management of the crab fishery around South Georgia

   levels of infection by a rhizocephalan barnacle have been found in the population of the crab Paralomis ... to declines in spawning stock. The effects of harvesting both healthy and infected animals are ... animals from the population. The need is stronger when the population is sensitive to declines in spawning ... stock. Results highlight the importance of incorporating parasitism in the design of a management ... animal is in the size range where the chela has started growing at the higher adult growth rate. Data ... the population-dynamics-at-age are given in the appendix, together with the parameters used in this ... spawning stock is already below its maximum level, even without any harvesting. 0 0 10 20 30 40 50 60 ... changes in spawning stock. 0- 60 0 (I) 40 (I) (I) ;j, 20 0 0 0.2 0.4 0.6 0.8 1 Fishing ...

   Science Journal Paper : CCAMLR Science, Volume 1 (CCAMLR Science, Volume 1) : 175–192 : Autor(es): Basson, M

2. Estimating the impact of depredation by killer whales and sperm whales on longline fishing for toothfish (Dissostichus eleginoides) around South Georgia

   whales have been more frequently encountered in recent years, occurring in larger pod sizes, whereas ... 3.8% and sperm whales on 17.7% of lines. Killer whales appear in pod sizes normally of 4 to 10 animals ... toothfish, usually depressing CPUE by about 50%. Sperm whales occur in smaller pod sizes, normally between 1 ... and 4 animals, and have a relatively lower impact on catches, depressing CPUE by up to 20%. Sperm ... , followed by two years of low interaction, and finally another year of very high interaction in 20009. The ... frequently encountered in recent years, occurring in larger pod sizes, whereas killer whale encounters and ... in recent years, most recently by Kock et al. (2008). Around South Georgia they were first recorded ... end of the season; over the seven years, 27% of observed sets have been set in May, 26% in June and ...

   Science Journal Paper : CCAMLR Science, Volume 17 (CCAMLR Science, Volume 17) : 163–178 : Autor(es): Moir Clark, J. and D.J. Agnew

3. Comparison of age readings from scales and otoliths of the Patagonian toothfish (Dissostichus eleginoides) from South Georgia

   region (Subarea 48.3). In 44% of specimens, age readings from both structures were identical. A Wilcoxon ... test for paired data (Ts = 0.256, n = 59) conducted on the remaining 56% showed that differences in age ... 24 years. This is very close to the maximum age of 22.8 years calculated from Taylor's formulae ... which relates maximum observed age to natural mortality. In this case we used M = 0.13, which is the ... . eleginoides is 223 cm. Sexual maturity is reached at about 90 to 100 cm total length (TL) (9-10 years) in ... about seven years, followed by a period when an increase in thickness is the main result of growth ... soaked for one week in a solution of 20% alcohol (96"), 5% glycerin, a few drops of domestic detergent ... , 1992 (SC-CAMLR-SSPI9). CCAMLR, Hobart, Australia: 21-30. (In Spanish) North, A.W. 1988. Age of ...

   Science Journal Paper : CCAMLR Science, Volume 5 (CCAMLR Science, Volume 5) : 191–203 : Autor(es): Cassia, M.C

4. Acoustic estimates of krill density at South Georgia, 1981 to 1998

   separate density estimates for northeastern and northwestern South Georgia, and in four of these seasons ... from year to year over that time, ranging from ≈ 2 to  ≈ 150 g m-2 (fresh mass). The 1982, 1991 and ... years; by convention the year given refers to the year in which the season ended) BAS has conducted ... given year is less than p - o for all years, then the year in Acoustic estimates of krill density ... ), four years exhibited greater density in the east. The year deviating from this pattern, 1994, was ... the year in which krill density at the island was the lowest of all years for which data are ...

   Science Journal Paper : CCAMLR Science, Volume 6 (CCAMLR Science, Volume 6) : 47–57 : Autor(es): Brierley, A.S., J.L. Watkins, C. Goss, M.T. Wilkinson and I. Everson

5. 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.

   process error in predicted catch-at-age numbers. Simulations assumed 1 000 releases per year over 12 years ... , using multiple cohorts and multiple years of catch-at-age and aged mark-recapture data was tested using ... perturbation by observational error were also carried out for each model in order to investigate the effect on ... estimates with that for M. In contrast, when sigmoidally shaped selectivity was simulated, and the ... fishing years. In order to apply equations (3) and (4) recursively from the start of fishing at year y ... response random variable is defined as the number of recaptures of ,iy aR in ith year of fishing years ... 12 fishing years starting in calendar year 2010, with this number of fishing years chosen to reflect ... historical collections of otoliths in recent years had allowed such datasets to be constructed as described ...

   Science Journal Paper : CCAMLR Science, Volume 18 (CCAMLR Science, Volume 18) : 1–27 : Autor(es): Candy, S.G.

6. Using ecosystem monitoring data to detect impacts

   an observed value in an unimpacted system, or (ii) the frequency of values below a fixed reference ... point. The second approach allows inference criteria based on changes in this frequency rather than by ... decline in Antarctic fur seal (Arctocephalus gazella) pup production at South Georgia from the early 1990s ... within a few years of its onset, but a fixed reference point method could have provided this sustained ... if at ≤ acrit in two or more years of a four-year refer- ence period. Summary of methods: anomalies ... : Method 4 with inference based on changes in frequency: the observed proportion of years in an n-year ... baseline PDF were then used to test for impacts in 20 more obser- vations drawn from the baseline period ... once in t years can be calculated using the binomial density function: P(at) = t.p.(1 – p)t (1 ...

   Science Journal Paper : CCAMLR Science, Volume 17 (CCAMLR Science, Volume 17) : 197–212 : Autor(es): Hill, S.L., J. Forcada, P.N. Trathan and C.M. Waluda

7. A simple approach for calculating the potential yield of krill from biomass survey results

   median pre-exploitation level over a 20 year period of harvesting should equal 10%. The value of, λ ... 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 ... the following 20 years, is that from a single pre-exploitation biomass survey. No account is taken of ... krill of length 20 mm and above (D. Miller, pers. comm.), so that the lengths listed in Table 1 suggest ... -exploitation level over a 20 year period of harvesting should equal 10%. The value of 'A, depends strongly on ... size drops below 20% of its average value prior to exploitation, over a 20 year period of harvesting ...

   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

8. On the power to detect changes using the standard methods for monitoring parameters of predatory species

   trip duration (C2.0). The other Standard Methods are not evaluated because the power analysis in the ... considered here are insufficient for conducting power analyses (penguin arrival weight A1.1, trend in penguin ... sample sizes for detecting changes of 10%, 20% and 30% of the mean values are shown in Table 2. No ... to distinguish between the mean values of parameters obtained in two or more years. We may also ... ) to compute the requisite sample sizes for detecting changes of 10%, 20% and 30% of the mean value ... in the two years was 24.3 hr. The mean duration of trips made by 47 pairs of chinstrap penguins was ...

   Science Journal Paper : Selected Scientific Papers, SC-CAMLR-SSP/6 (Selected Scientific Papers, SC-CAMLR-SSP/6) : 377–397 : Autor(es): Boveng, P. and J.L. Bengtson

9. Some thoughts on precautionary measures for the krill fishery

   (WG-Krill) is discussed and it is concluded that such a method is appropriate in setting an overall ... precautionary catch limit in large areas, such as Statistical Area 48, but the approach requires considerable ... is 10%; and the median krill escapement1 in the spawning biomass over a 20-year period is 75% of ... spawning biomass dropping below 20% of its pre-exploitation median level over a 20-year harvesting period ... during the course of a year. In order to incorporate this into equation (l), the level of annual ... turnover of twice each year (based on Everson, 1992), the instantaneous standing stock in the area would ...

   Science Journal Paper : CCAMLR Science, Volume 3 (CCAMLR Science, Volume 3) : 1–11 : Autor(es): Everson, I. and W.K. de la Mare

10. An index of per capita recruitment

    years, and when all age-l animals spawn. These conclusions are insensitive to changes in the shape of ... spawners and recruits. PCR was also able to track cycles in recruits per spawner after a 20% random ... recruitment (PCR) is proposed such that where R 1 is the proportion of age-l animals sampled in year y and M ... in mortality and reduction in the proportion of age-l spawners. Introducing year-to-year random ... appearing as a large mode at 20 to 30 mm length and in subsequent years as progressively longer length ... as age-l animals. In the intervening years without strong year classes the dominant length mode is ... . PCR was also able to track cycles in recruits per spawner after a 20% random sampling error was added ... capita recruitment (PCR). Such a measure could be obtained with surveys in successive years provided ...

    Science Journal Paper : CCAMLR Science, Volume 7 (CCAMLR Science, Volume 7) : 179–196 : Autor(es): Hewitt, R

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