CCAMLR

The purpose of this paper is to respond to a request made at the XXXII CCAMLR meeting in 2013 for ACAP to provide information on the levels of seabird bycatch in fisheries adjacent to the CCAMLR Convention area. A summary of the most recent bycatch and related information held by ACAP is presented, and the current status of the process to develop a bycatch data reporting and assessment framework is reported. It is noted that work is ongoing in this respect, and that the information provided represents that which has been provided by Parties to date, and that these data have not yet been further assessed or analysed. In relation to Regional Fisheries Management Organisations (RFMOs), it is reported that there is a general need to improve levels of bycatch reporting, and in some cases to develop or refine data collection and reporting protocols, so that levels of seabird bycatch and the efficacy of mitigation measures required can be properly assessed and monitored. Initiatives that are currently underway to help address these needs are highlighted.

In 2013 New Zealand and the USA submitted a draft research and monitoring plan to accompany a proposal for a Marine Protected Area in the Ross Sea region.  In this paper we describe new research projects planned or initiated since submission of that plan, to address priority research activities identified therein. We also identify new research proposals submitted in the past year that are also expected to address priority activities identified in the plan. All CCAMLR Members are encouraged to contribute to this list describing their own planned or ongoing research projects, and to engage in multi-Member collaboration toward the implementation of a genuinely multi-Member ecosystem research and monitoring programme in the Ross Sea region.   

A proposal for a Marine Protected Area in the Ross Sea region has been submitted to CCAMLR and iteratively updated since 2012 consistent with Scientific Committee advice.  The purpose of this paper is to: 1)  identify previously submitted scientific documents supporting MPA planning in the Ross Sea region; 2) highlight relevant Scientific Committee advice to support or modify previous iterations of this proposal; and 3) update relevant maps, figures and analyses from previously submitted scientific papers to reflect the boundaries of the current MPA proposal and with updated fishery data, to assist evaluation of the current proposal.  

I made six sensitive runs of CASAL models (LENGTH/AGE_IUU_MODEL) for stock status assessments of Dissostichus eleginoides in research block C in Division 58.4.4 b following the recommendation during the latest WG-SAM meeting. The six models with three kinds of assumptions on IUU catch were arranged referring to WG-SAM-14/18 as follows: 1) catch at length/age models on the assumption of no IUU fishing occurrence (Len_1/AgeSing_1 models), 2) catch at length/age models with estimation of IUU catch within the model using disease mortality functionality (Len_2/AgeSing_2 models), 3) catch at length/age models on the assumption that 22 % of IUU catch to the total observed across Division 58.4.4 occurred in the block (Len_3/AgeSing_3 models). Single age-length key (ALK) was used for each age structured model. Selectivity and associated index for disease mortality were estimated for Len_2/AgeSing_2 models but the selectivity for IUU fishery was fixed for Len_3/AgeSing_3 models. The other common conditions among six models were set as follows: parameters for ALK (k, Linf and t0) were fixed; year class strength (YCS) was estimated; double-normal selectivity for legal fishery was estimated; mean-based weighting method was used for proportion-at-length/age and tag-recapture; uniform prior was used for initial biomass (B₀) estimate.

The MPD estimates of the initial and current spawning biomass and current vulnerable biomass were highest for models on the assumption of 22% of total IUU catch and lowest for models with assumption of no IUU catch for both size- and age structured models. The age structured models were higher in each kind of biomass than size structured models for each assumption of IUU catch condition.

Every model showed more convergence in MCMC posterior trace for B₀ compared to my previous versions. MCMC estimates for median biomasses became larger than the MPD ones for each model, but the difference between them was considerably smaller compared to my previous versions.

Further sensitivity runs derived from Len_1 model (LEN_1_DER_MODEL) were examined using eight options changing conditions, i.e. estimate/fix for given parameters, uniform-log prior for B₀, and multinomial-based weighting for proportion-at-length and/or tag-recapture. From the results, the smaller differences between MPD estimates of median B₀ and MCMC ones and more convergence in MCMC posterior trace for B₀ for the current LENGTH/AGE_IUU_MODEL runs compared to my previous versions seem to be due to the use of the mean-based weighting instead of multinomial-based weighting used in my previous versions.

This report does not yet address the investigation on likely fixed selection patterns for estimation of IUU catches for Len/AgeSing_2 models (para. 2.24 (iii) of WG-SAM-2014 report). I need advice about the methods during WG-FSA meeting.

I made two sensitive runs of CASAL catch at length models (LENGTH_MODEL) for stock status assessments of Dissostichus eleginoides in research block 5843a_1 in Division 58.4.3a for the years 2004/05 to 2012/13 following the recommendation during the last WG-SAM meeting. The two models are generally based on those with the same names in WG-SAM-14/17 as follows: 1) R.0.1 model without tagging events before 2008, and 2) R.1 model including all tagging events (years 2005-2012). These models were comprised of two fisheries split by depths of 1 200 m as the model in WG-SAM-14/17.  Number of longlines was used as (unknown) multinomial sample size for each model. The over-dispersion for the tag-recapture likelihoods was estimated using a mean-based weighting method for each model. The other common conditions between the two models were set as follows: year class strength (YCS) was fixed; parameters of ALK were fixed; parameters of selectivity for legal fishery were estimated; uniform prior was used for initial biomass (B₀) estimate.

The MPD estimate of B₀ was 464 and 772 tonnes in R.0.1 and R.1 models, respectively. The current vulnerable biomass was 647 and 1 201 tonnes, respectively. The median MCMC estimates for the biomasses (490 and 810 tonnes) were slightly higher than those by MPD for each model. MCMC posterior traces for B₀ seem to be rather convergent for each model.

Further sensitive runs for R.1 model (R.1_DER_MODEL) were examined using six options changing conditions, i.e. estimate/fix for given parameters, uniform-log prior for B₀, and multinomial-based weighting for tag-recapture. The difference of median estimate of B₀ between MPD and MCMC and the range of MCMC were considerably large for R.1_2 model, which used multinomial-based weighting for tag-recapture that lead to quite high value of dispersion.

In this document, we revise stock status assessments of D. eleginoides in research blocks C and D using CPUE analogy method, Petersen method and CASAL model, although the data of current season has not been validated and not used for the present analysis. We used updated reference area size for the CPUE method and altered natural mortality for the Petersen and CASAL methods. Detailed results using CASAL models in research block C are described in a separated document.

The estimated stock size in block C was 709, 401 and 850 tonnes in CPUE analogy method, Petersen method and CASAL Len_1 model (vulnerable biomass in 2013), respectively.

The stock sizes of D. eleginoides in block D is estimated at 948 tonnes only by using CPUE method, as the catch and tagging data in block D was not enough to be applied to Petersen method and CASAL models.

We propose to continue the current research operation for the next fishing season with the same survey design and sample size of 60 tonnes in order to further strengthen the stock assessments in the area.