The Agreed Method to Determine the Maximum Sardine Catch West of Cape Agulhas During 2017

This document details the method agreed at the Small Pelagic Scientific Working Group meeting on 27th June 2017 to be used to inform the maximum directed >14cm sardine catch to be recommended to be caught west of Cape Agulhas during 2017. The agreement involves setting the maximum directed >14cm sardine catch west of Cape Agulhas for 2017 to the average of the maximum catch calculated from two different methods. Note that this maximum may also not be more than the total directed >14cm sardine TAC for 2017 as calculated by OMP-14

A proposal for determining the final desirable maximum catch of directed sardine west of Cape Agulhas during 2017

The maximum directed >14cm sardine catch recommended to be caught west of Cape Agulhas during 2017 was initially set at 21 400t (DAFF 2016) based on the method set out in de Moor and Butterworth (2016). The mid-year revision in the South African sardine and anchovy TACs and TABs for 2017 is to be based on OMP-14, as OMP-17 is still under development. The maximum directed >14cm sardine catch recommended to be caught west of Cape Agulhas thus requires some revision to take account of further work on the underlying sardine Operating Model and information resulting from the 2017 recruit survey

The two mixing stock hypothesis for South African sardine without an assumed stock-recruit relationship

The two mixing stock hypotheses for South African sardine presented in de Moor and Butterworth (2016) and de Moor (2016) assumed a Hockey-Stick stock-recruit relationship, with the stock-recruit parameters estimated to differ by “effective spawning stock”. In addition, recruitment to the west stock during the “peak” 2000-2004 years was estimated to vary about a different median level. In this document the two-mixing stock hypothesis is re-run without any assumed stock-recruit relationship

Hashing protocol for distilling multipartite CSS states

We present a hashing protocol for distilling multipartite CSS states by means of local Clifford operations, Pauli measurements and classical communication. It is shown that this hashing protocol outperforms previous versions by exploiting information theory to a full extent an not only applying CNOTs as local Clifford operations. Using the information-theoretical notion of a strongly typical set, we calculate the asymptotic yield of the protocol as the solution of a linear programming problem.Comment: 13 pages, 3 figures, RevTeX

Algorithms for deterministic balanced subspace identification

New algorithms for identification of a balanced state space representation are proposed. They are based on a procedure for the estimation of impulse response and sequential zero input responses directly from data. The proposed algorithms are more efficient than the existing alternatives that compute the whole Hankel matrix of Markov parameters. It is shown that the computations can be performed on Hankel matrices of the input–output data of various dimensions. By choosing wider matrices, we need persistency of excitation of smaller order. Moreover, this leads to computational savings and improved statistical accuracy when the data is noisy. Using a finite amount of input–output data, the existing algorithms compute finite time balanced representation and the identified models have a lower bound on the distance to an exact balanced representation. The proposed algorithm can approximate arbitrarily closely an exact balanced representation. Moreover, the finite time balancing parameter can be selected automatically by monitoring the decay of the impulse response. We show what is the optimal in terms of minimal identifiability condition partition of the data into “past” and “future”

Assessment of the South African sardine resource using data from 1984-2015: Results at the joint posterior mode for the single stock hypothesis

The assessment of the South African sardine resource has been revised and updated using data available up to November 2015. Two primary hypotheses regarding the sardine stock structure have been agreed for investigation. The first considers sardine distributed off the west and south coasts of South Africa to form a single homogeneous “stock” (or “population”). The second considers the sardine to consist of a western stock and southern stock with some mixing between the two. While there is growing evidence supporting the existence of sub-population structure amongst sardine distributed off the west and south coasts of South Africa (e.g. Coetzee et al. 2008, van der Lingen et al. 2009, 2015, van der Lingen 2011, Weston et al. 2015), the single stock hypothesis continues to be modelled as it allows for easy comparison to past assessments and, in particular, to past risk statistics and previous Operational Management Procedures. It also reflects a limiting case of the mixing model as the extent of mixing becomes very large. This document presents results at the joint posterior mode for the single stock hypothesis only

Assessment of the South African sardine resource using data from 1984-2015: Results at the joint posterior mode for the single stock hypothesis

The assessment of the South African sardine resource has been revised and updated using data available up to November 2015. Two primary hypotheses regarding the sardine stock structure have been agreed for investigation. The first considers sardine distributed off the west and south coasts of South Africa to form a single homogeneous “stock” (or “population”). The second considers the sardine to consist of a western stock and southern stock with some mixing between the two. While there is growing evidence supporting the existence of sub-population structure amongst sardine distributed off the west and south coasts of South Africa (e.g. Coetzee et al. 2008, van der Lingen et al. 2009, 2015, van der Lingen 2011, Weston et al. 2015), the single stock hypothesis continues to be modelled as it allows for easy comparison to past assessments and, in particular, to past risk statistics and previous Operational Management Procedures. It also reflects a limiting case of the mixing model as the extent of mixing becomes very large. This document presents results at the joint posterior mode for the single stock hypothesis only

Discussion of OMP-17 simulation projection framework in respect of sardine

The simulation projection framework to be used to test Candidate Management Procedures for OMP-17 is yet to be developed (cf de Moor and Butterworth (2013a) for the framework used when developing OMP-14). However, given experience gained during the testing of OMP-14, some initial assessment results (de Moor and Butterworth 2016a,b) and discussions in the SPSWG, we can begin to consider some alternative key assumptions to be used in the simulation projection framework to be used for developing OMP-17

Local permutations of products of Bell states and entanglement distillation

We present new algorithms for mixed-state multi-copy entanglement distillation for pairs of qubits. Our algorithms perform significantly better than the best known algorithms. Better algorithms can be derived that are tuned for specific initial states. The new algorithms are based on a characterization of the group of all locally realizable permutations of the 4^n possible tensor products of n Bell states.Comment: 6 pages, 1 figur