Résultats de la recherche

1. 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 ... -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 ... steady growth throughout the year. In contrast, krill exhibits growth which varies systematically over ... krill of length 20 mm and above (D. Miller, pers. comm.), so that the lengths listed in Table 1 suggest ...

   Science Journal Paper : Selected Scientific Papers, SC-CAMLR-SSP/8 (Selected Scientific Papers, SC-CAMLR-SSP/8) : 207–217 : Auteur(s): Butterworth, D.S., A.E. Punt and M. Basson

2. 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 ... by routine monitoring at the actual sampling intensity attained in each year, a more useful approach ... ) to compute the requisite sample sizes for detecting changes of 10%, 20% and 30% of the mean value ... measured. In general, the sample of birds monitored one year is not the same as the sample monitored the ...

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

3. 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 : Auteur(s): Everson, I. and W.K. de la Mare

4. 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 ... in mortality and reduction in the proportion of age-l spawners. Introducing year-to-year random ... spawners and recruits. PCR was also able to track cycles in recruits per spawner after a 20% random ... sampling error was added to the value of R 1 used in the calculation of PCR and 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 ... where R1 is the proportion of age-l animals sampled in year y and M is the post-recruit mortality rate ... proportion of age-l spawners. Introducing year-to-year random variability in both mortality and proportion ...

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

5. A review of the diet and at-sea distribution of penguins breeding within the CAMLR Convention Area (submitted to the 2008 Joint CCAMLR-IWC Workshop)

   in an ecologically sensitive manner demands that catches do not depress stocks within the foraging ... . These models require information on the number of predators in a population, their nutritional demands ... , their diet composition and their seasonal distribution in the marine environment. This paper reviews all ... published information on the diet and at-sea distribution of the six penguin species that breed in the CAMLR ... does cause birds distress, and in exceptional cases results in death of a study animal, but it is ... be stored in 70% alcohol or frozen at –20°C, but feathers, toenails, eggshell and bone require no ... markedly from year-to-year (e.g. Barlow and Croxall, 2002; Crawford et al., 2003), often in response to ... 1994. Birds travelled for c. 30 days to areas of perennially consistent pack- ice in the eastern Ross ...

   Science Journal Paper : CCAMLR Science, Volume 19 (CCAMLR Science, Volume 19) : 75–114 : Auteur(s): Ratcliffe, N. and P. Trathan

6. Movement, growth and available abundance to the fishery of Dissostichus eleginoides Smitt, 1898 at Heard Island, derived from tagging experiments

   Patagonian toothfish (Dissostichus eleginoides) in different sectors of the Southern Ocean are considered to ... be genetically distinct. However, in the Indian Ocean, it is largely unknown whether stocks are ... separation using tagged fish from the fishery around Heard Island and McDonald Islands (HIMI) in the ... Australian Exclusive Economic Zone (EEZ). Movement, growth and trends in fish abundance are examined using ... 22 10 7 20 4 30 6 Fi sh in g gr ou nd C 23 7 50 51 0 18 7 39 13 9 25 Pl at ea u ... la bl e nu m be rs (m ill io ns ) 1998 1999 2000 2001 Year 0 10 20 30 40 50 Pr ed ic ... te d nu m be rs (m illi on s) 1998 1999 2000 2001 Year 50 40 30 20 10 0 P re di ct ... 00 30 00 40 00 40 00 30 00 30 00 20 00 10 00 50 0 M A R IO N /P . E D W A R D CR O ZE ...

   Science Journal Paper : CCAMLR Science, Volume 9 (CCAMLR Science, Volume 9) : 33–48 : Auteur(s): Williams, R., G.N. Tuck, A.J. Constable and T. Lamb

7. CCAMLR ecosystem monitoring and management: future work

   :  Harvesting of marine living resources in the Southern Ocean is managed by the Commission for the Conservation ... managing fisheries with the maintenance of ecological relationships included in the conservation objectives ... . In the late 1980s, CCAMLR’s precautionary approach was developed, incorporating principles of how to ... use scientific evidence in the decision-making process. Even though this approach was based on the ... of sampling within a year in order to determine the relationship between krill and predators for ... . Consequently, changes in predator performance from one year to the next may simply be due to this natural ... -scale effects on abundance in a given year Ea Small-scale effects on availability in a given year Ef ... scale during the early stages of the fi shery and to 0 1 2 3 0 1 2 3 D en si ty 0 10 20 30 ...

   Science Journal Paper : CCAMLR Science, Volume 9 (CCAMLR Science, Volume 9) : 233–253 : Auteur(s): Constable, A.J

8. The ecosystem approach to managing fisheries: achieving conservation objectives for predators of fished species

   in its infancy. A general approach is proposed for maintaining ecological relationships and providing ... for the recovery of depleted populations in food webs supporting fisheries. This paper addresses the ... objectives? The approach proposed here takes account of uncertainties in knowledge of the structure of ... ecosystems. Estimates of predator production arising from the consumption of fished species (encapsulated in ... 20-30 years, wl~ich is the critical period over which the system should not be irreversibly changed ... zero after 20 years. Prey 2 is more abundant (-3x) than Prey 1 in the absence of fishing and then ... years (see text for details). Year Figure 7: Individual productivity for each predator in the trial ... discussed here. year to the next, such that there inay be more predators of fished species in years when ...

   Science Journal Paper : CCAMLR Science, Volume 8 (CCAMLR Science, Volume 8) : 37–64 : Auteur(s): Constable, A.J

9. Effects of weather and sea-ice on the reproductive performance of the Adélie penguin at Edmonson Point, Ross Sea

   seasons. Weather and sea-ice regimes varied notably, especially in 2003, which was characterised by ... extensive and persistent sea-ice and strong winds with snowfalls in December. First incubation trips by ... females were significantly longer than in 1999 and 2001, which in turn delayed the mean departure date of ... delayed compared to dates recorded in 1999 and 2001. The average weight of adults rearing chicks was lower ... 0 10 20 30 40 50 60 70 80 W in d s p e e d ( k n o ts ) n = 97 n = 76 ... -January. In 2003 the fast-ice again extended about 20 km but, unlike the previous year, it did not ... -ice regimes (Ainley, 2002). Sea-ice may vary in persistence, concentration and extent from year to ... conditions varied during the three seasons (Figure 1). In 1999 maximum wind speed exceeded 30 knots on a ...

   Science Journal Paper : CCAMLR Science, Volume 11 (CCAMLR Science, Volume 11) : 99–109 : Auteur(s): Olmastroni, S., F. Pezzo, V. Volpi and S. Focardi

10. Sensitivity investigation of the SDWBA Antarctic krill target strength model to fatness, material contrast and orientation

    the distribution of animal orientations. Due to the high variability of TS to realistic changes in ... model is recognised as state-of-the-art in predicting acoustic target strength (TS) from fluid-like ... TS of Antarctic krill (Euphausia superba) for use in the acoustic echo-integration method. In this ... study, the SDWBA TS pattern and frequency response behaviours at standard survey frequencies and animal ... the along-axis deforma- tion and changes in animal body curvature during swimming. With a successive ... if that animal is representative of krill in the wild. In their validation of the SDWBA model to ... rb a M . n or ve gi ca N [4 5. 3, 30 .4 ] N [5 3. 8, 64 .2 ] O bs er va tio n in ... ] O bs er va tio n in a qu ar iu m C hu e t a l., 1 99 3 E. su pe rb a N [ 20 ...

    Science Journal Paper : CCAMLR Science, Volume 18 (CCAMLR Science, Volume 18) : 97–122 : Auteur(s): Calise, L. and G. Skaret

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