Résultats de la recherche

1. Evaluating the impact of multi-year research catch limits on overfished toothfish populations

   populations Abstract / Description:  In stocks that have been depleted by overfishing, the benefit of ... research catches, this study shows that stocks can take decades to recover even in the absence of fishing ... assessed in this study indicate that, where a stock has been depleted to at or below 20% of the median ... unfished spawning stock biomass, research catches in excess of 0.6% of median unfished total stock biomass ... 2009 (SC-CAMLR, 2009b)) and declining catches by the authorised fleet in the fishery (Divisions ... in 2002 (CCAMLR, 2002). The relationship of the stock on Ob and Lena Banks to other stocks in the ... research fishing, SC-CAMLR has agreed that research should be conducted in such a way that it does not ... impact on the recovery of the stock, while any data collection plan which may in- volve research fishing ...

   Science Journal Paper : CCAMLR Science, Volume 18 (CCAMLR Science, Volume 18) : 47–55 : Auteur(s): Welsford, D.C

2. On the instantaneous natural mortality rate of Champsocephalus gunnari, South Georgia (Subarea 48.3)

   Champsocephalus gunnari in the South Georgia area was assessed using six different methods. Data on size ... composition of catches from 1964/65 to 1968/69 and the age/length key for the first half of 1972 were used in ... suggested that M =0.56 should be used in stock assessment for C. gunnari in Subarea 48.3. File:  19-Frolkina ... * * Abstract The instantaneous rate of natural mortality (M) of Champsocephalus gunnari in the South Georgia ... 1968/69 and the age/length key for the first half of 1972 were used in the calculations. The results ... used in stock assessment for C. gunnari in Subarea 48.3. Resume Le taux instantane de mortalite ... , Beverton and Holt and several other methods. Therefore in 1989 the CCAMLR Working Group on Fish Stock ...

   Science Journal Paper : Selected Scientific Papers, SC-CAMLR-SSP/7 (Selected Scientific Papers, SC-CAMLR-SSP/7) : 313–326 : Auteur(s): Frolkina, G.A. and R.S. Dorovskikh

3. Modelling catch and effort data using generalised linear models, the Tweedie distribution, random vessel effects and random stratum-by-year effects

   CCAMLR areas is to model the haul-by-haul ratios of catch to effort as the response variable in a ... . Tweedie distribution) for catch that, unlike lognormal or gamma distributions, admits zero values. In ... model (GLMM), in order to provide more efficient estimates of the standardised CPUE time series and more ... as a result of the imbalance in the number of hauls in the year-by-vessel cross-classification ... in a generalised linear model (GLM) with a square-root link function and a unit variance function. A ... values. In addition, random vessel effects are introduced into the GLM, as specifi ed by a generalised ... linear mixed model (GLMM), in order to provide more effi cient estimates of the standardised CPUE time ... -vessel information as a result of the imbalance in the number of hauls in the year-by-vessel cross ...

   Science Journal Paper : CCAMLR Science, Volume 11 (CCAMLR Science, Volume 11) : 59–80 : Auteur(s): Candy, S.G

4. 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 ... 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 ... functional form of selectivity was correctly specified in the BODE model, both models gave close to unbiased ... the BODE model requires an extra component to the log-likelihood which defines the process error in ... error were also carried out for each model in order to investigate the effect on estimation of M ... with that for M. In contrast, when sigmoidally shaped selectivity was simulated, and the functional ... form of selectivity was correctly specified in the BODE model, both models gave close to unbiased and ...

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

5. Estimation of effective sample size for catch-at-age and catch-at-length data using simulated data from the Dirichlet-multinomial distribution

   ‘effective sample size’ (ESS) in integrated assessments is an approximate but simple way of modelling the ... empirical coefficient of variation (CV) in the proportions, with one being based on an existing CV model ... accuracy in the following order: (i) the estimator based on the existing CV model; (ii) that based on the ... method. To account for process error in the calculation of the ESS, the lack of fit of the age-structured ... Email – steve.candy@aad.gov.au Abstract The incorporation of ‘effective sample size’ (ESS) in ... for the empirical coefficient of variation (CV) in the proportions, with one being based on an ... with increasing accuracy in the following order: (i) the estimator based on the existing CV model ... than the best haul-level method. To account for process error in the calculation of the ESS, the lack ...

   Science Journal Paper : CCAMLR Science, Volume 15 (CCAMLR Science, Volume 15) : 115–138 : Auteur(s): Candy, S.G

6. The choice of procedure for deciding when to close fisheries regulated by CCAMLR: a simulation model

   simulation model Abstract / Description:  The methods, described in CCAMLR Conservation Measures, used for ... implement because of the variation in catch rates shown by the fisheries. Non-fluctuating random and ... decisions is investigated under a variety of circumstances. The model described in the existing conservation ... reporting periods are small (five days) and the reporting delay is minimal. It is recommended that in future ... , described in CCAMLR Conservation Measures, used for deciding the closure date for fisheries monitored by ... the Secretariat of CCAMLR, have been difficult to implement because of the variation in catch rates ... circumstances. The model described in the existing conservation measures is shown to have a high probability ... days) and the reporting delay is minimal. It is recommended that in future conservation measures ...

   Science Journal Paper : Selected Scientific Papers, SC-CAMLR-SSP/9 (Selected Scientific Papers, SC-CAMLR-SSP/9) : 81–97 : Auteur(s): Agnew, D.J.

7. Spatial distribution of management measures, Antarctic krill catch and Southern Ocean bioregions: implications for conservation planning

   between habitat (bioregion), existing spatial management and Antarctic krill catch in the Southern Ocean ... important differences between pelagic bioregions in terms of the fraction that was open to fishing, and the ... has ever been fished, and this fishing is concentrated in three of the seven bioregions found in the ... be used to prioritise protection for bioregions that are currently under-represented in marine ... CCAMLR has endorsed the development of a representative system of marine protected areas (MPAs) in the ... scales that are appropriate in terms of both conservation benefits and rational use. A conservation ... measure (CM) agreed by the Commission in 2011 (CM 91-04) sets out a general framework for establishing ... their viability and integrity in the long term...’ (CCAMLR, 2011). There are many approaches to the ...

   Science Journal Paper : CCAMLR Science, Volume 20 (CCAMLR Science, Volume 20) : 1–19 : Auteur(s): Grant, S.M., S.L. Hill and P.T. Fretwell

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

   (Champsocephalus gunnari) in Subarea 48.3 employs the CCAMLR mixture analysis program (CMIX) and generalised yield ... accurate identification of age cohorts from the survey data. In this paper a length-based approach is ... data which, in conjunction with the bootstrapped survey biomass data, yields an estimate of the ... showed very good agreement in calculated yields for 2006, 2007 and 2009, and some differences for 2008 ... mackerel icefish (Champsocephalus gunnari) in Subarea 48.3 employs the CCAMLR mixture analysis program ... (TAC). One issue is the accurate identification of age cohorts from the survey data. In this paper a ... population from the survey data which, in conjunction with the bootstrapped survey biomass data, yields an ... /GYM methodology showed very good agreement in calculated yields for 2006, 2007 and 2009, and some ...

   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

9. Utilising data from ecosystem monitoring for managing fisheries: development of statistical summaries of indices arising from the CCAMLR Ecosystem Monitoring Program

   correlated (>0.6). Criteria for inclusion of parameters in the indices are discussed when parameters are ... statistical procedure adopted by WG-EMM in 1996 for identifying anomalies in CEMP parameters. The power of the ... appeared in the data. An alternative procedure, using estimates of the mean and variance of baseline time ... in CCAMLR. File:  06delamare-constable.pdf ... correlated (>0.6). Criteria for inclusion of parameters in the indices are discussed when parameters are ... statistical procedure adopted by WG-EMM in 1996 for identifying anomalies in CEMP parameters. The power of ... values have appeared in the data. An alternative procedure, using estimates of the mean and variance of ... for application in CCAMLR. Description d'une methode susceptible de combiner les donnees collectees ...

   Science Journal Paper : CCAMLR Science, Volume 7 (CCAMLR Science, Volume 7) : 101–117 : Auteur(s): de la Mare, W.K. and A.J. Constable

10. Estimates of circumpolar abundance of Antarctic krill based on recent acoustic density measurements

    tonnes- at the low end of values that have been suggested in the past. The differences between our ... . Additionally, the current precautionary catch limits in the South Atlantic are set using a superseded acoustic ... survey of the South Atlantic in January 2000 may result in an effective biomass which is greater than the ... value used in the past. The seasonal and local consequences of large catch limits will have to be taken ... that have been suggested in the past. The differences between our estimates and others can be ... precautionary catch limits in the South Atlantic are set using a superseded acoustic target strength which has ... effectively underestimated the krill biomass by a factor of three, so the new survey of the South Atlantic in ... January 2000 may result in an effective biomass which is greater than the value used in the past. The ...

    Science Journal Paper : CCAMLR Science, Volume 7 (CCAMLR Science, Volume 7) : 87–99 : Auteur(s): Nicol, S., A.J. Constable and T. Pauly

Pages