CCAMLR

Regarding the low levels of stocks of Dissostichus spp. and the high levels of IUU fishing, CCAMLR decided to close the fishery in 2002 in division 58.4.4. Since 2008 only one vessel, Shinsei maru No. 3, had conducted research fishing in accordance with a research plan submitted under CM 24-01. In 2014, WG-FSA agreed research fishing conducted in the research blocks C and D by two vessels using longlines: Shinsei Maru No. 3 (Japan) and the Saint André (France). For the season 2014/15, the catch limit for Dissostichus spp. is 25 tons for SSRU C and 35 tons for SSRU D. France notified its intention to achieve a robust stock assessment that would provide advice on a catch limit according to CCAMLR decision rules. This paper aims to present a research plan for 2015/2016 that takes into account the remarks made during the WG-FSA 2014. In SSRU 58.4.4D, tag recaptures are insufficient (the first tag recaptures were obtained in 2014), and consequently stock abundance (around 800 tonnes) has been estimated using the ‘CPUE seabed area analogy’ method. The biomass in division SSRU C was estimated during WG-FSA 2014 using a CASAL model constructed for D. eleginoides. The vulnerable biomass was estimated around 700 tonnes. CASAL model is updated with 2014 data but in the absence of an assessment using the CCAMLR decision rules, the catch limit should remain unchanged for 2015/16 to maximize the expectation of tag-recapture: SSRU C at 25 tons and SSRU D at 35 tons.

Antarctic ecosystems are dynamic and characterized by physically forced variability caused e.g. by fronts, eddies and ice. This creates a challenging dynamics for scientific sampling and monitoring. Realistic understanding of what can and cannot be achieved with the available sampling techniques and strategies is essential. This paper focuses on approaches for observing processes at the time-space scales at which they occur, which is essential for some of the management challenges of CCAMLR, for example the FBM.  

Sustainable management of fisheries resources requires quantitative knowledge and understanding of species distribution, abundance, and productivity-determining processes. Conventional sampling by physical capture is inconsistent with the spatial and temporal scales on which many of these processes occur. In contrast, acoustic observations can be obtained on spatial scales from centimetres to ocean basins, and temporal scales from seconds to seasons. The concept of marine ecosystem acoustics (MEA) is founded on the basic capability of acoustics to detect, classify, and quantify organisms and biological and physical heterogeneities in the water column. Acoustics observations integrate operational technologies, platforms, and models and can generate information by taxon at the relevant scales. The gaps between single-species assessment and ecosystem-based management, as well as between fisheries oceanography and ecology, are thereby bridged. The MEA concept combines state-of the-art acoustic technology with advanced operational capabilities and tailored modelling integrated into a flexible tool for ecosystem research and monitoring. Case studies are presented to illustrate application of the MEA concept in quantification of biophysical coupling, patchiness of organisms, predator–prey interactions, and fish stock recruitment processes. Widespread implementation of MEA will have a large impact on marine monitoring and assessment practices and it is to be hoped that they also promote and facilitate interaction among disciplines within the marine sciences.

The Secretariat has embarked on a major overhaul of CCAMLR data holdings and associated IT and data infrastructure. This work, which begun in 2013, includes developing an Enterprise Data Model, redeveloping the CCAMLR database, improving data quality assurance, and modernising the data work flow.

The user community can expect to notice significant improvements in data quality and database documentation as the new system is rolled out from late 2015. Consequential changes will be required in requested data extracts to reflect the new data model and nomenclature.

This paper provides an update on progress.

Subareas 58.6 and 58.7 are closed to fishing outside of the Exclusive Economic Zones (EEZs) around the Crozet (France) and Prince Edward (South Africa) Archipelagos. The current boundary between Subareas 58.6 and 58.7 bisects the South African EEZ around the Prince Edward Islands. Thus fishery statistics reported for Subarea 58.7 reflects only part of the fishery in the South African EEZ, whereas statistics for Subarea 58.6 reflects data for the fisheries in the French EEZ at the Crozet Archipelago and part of the South African EEZ combined. As a result statistics reported by Subarea are of no use for management of the fisheries in these two Subareas. We propose that the boundary between Subareas 58.6 and 58.7 be repositioned on the 44°E meridian so that it falls in the high seas between the French and South African EEZs, and corresponds to the existing boundary between SSRUs 58.6A and 58.6B.

A multi-year research plan as outlined in CM 41-04 (2012, 2013 & 2014) was initiated Statistical Subarea 48.6 by Japan and South Africa during the 2012/13 fishing season. Two vessels participated in the research project in each of the three fishing seasons and the progress achieved during the first 2.5 years is reported.

Between December 2012 and April 2015 a total of 291 Dissostichus eleganoides and 3273 D. mawsoni were tagged and released, and a total of 10 and 49 tagged D. eleganoides and D. mawsoni, respectively were recaptured. It is encouraging that 10 tagged D. mawsoni have been recaptured in the southern half of Subarea 48.6 already in the current season, more than total number for all previous seasons.

To date for the first three years of the research project biological data have been collected from 25 052 toothfish and length data from a total of 15 157 individuals from 18 different species.

Two-area population models for Antarctic toothfish in the Amundsen Sea Region were developed further as current single area models did not fully explain the patterns in the observed data on tag recaptures and age composition. Although the hypothesised stock structure spans SSRUs 88.2C–H, these models were limited to data collected in SSRU 88.2H as there were few data available to inform estimation of biomass in SSRUs 88.2C–G. Additional data resulting from a two-year research plan implemented in 2014/15 are expected to better inform the assessment of the entire stock including SSRUs 88.2C–G in the future.

Results showed that a two-area model with sex- and age-specific migrations from SSRUs 88.2C-G to SSRU 88.2H and back provided the best fits to the age and tag data collected in SSRU 88.2H. Furthermore, a resident population in 88.2H was not required to explain the patterns observed in the data, nor was annually-varying or density-dependent migration. Finally, using subsets of the data, or excluding small tagged fish, did not improve the fits to the data.

We recommend this model be further developed once additional age and tag data have been collected in SSRUs 88.2C–H as part of the two-year research plan. 

Appendix: CASAL files

Management Strategy Evaluation (MSE) has been acknowledged as the best practice to take account of uncertainties in the assessment of stocks and as a method to ensure robust management approaches. The Scientific Committee of CCAMLR has recommended MSE be used to determine the extent to which the management objectives for toothfish fisheries are being met. While the choice of management targets used by CCAMLR has been based on MSE simulations, formal MSE studies have yet to be fully implemented.

To date there have been a number of analyses and simulation studies reported for the assessment of toothfish that have evaluated the sensitivity of models and the resulting estimates of sustainable yields with respect to management objectives.

In this paper we develop approaches using operating and estimation models and show how they can be used to assist in identifying aspects of model and parameter misspecification that could then be evaluated using more computationally complex MSE approaches. We apply this to the assessment of Antarctic toothfish in the Ross Sea region with some example parameters and parameter values.

Our results can assist in prioritising further MSE analyses that fully account for the feedback mechanisms that the CCAMLRs decision rules provide. However, we note that different assessment models may be sensitive to different parameters and parameter values, and may require different approaches to MSE. We also note the importance of developing and maintaining data collections that can contribute to more accurate parameter specifications for any parameters identified as priorities through the MSE process.

We propose to conduct a scientific survey during the austral winter in the northern Ross Sea region to investigate spawning dynamics of Antarctic toothfish, as requested by the Scientific Committee in 2013. The longline survey is designed to cover key gaps in the knowledge of the life cycle of Antarctic toothfish (Dissostichus mawsoni) in the Ross Sea by collecting biological samples from a range of locations in Subarea 88.1 SSRUs B–C and begin in June 2016. The survey has two primary objectives, which are to investigate the spawning timing and locations of Antarctic toothfish in the northern Ross Sea region; and to investigate the maturity status, gonadosomatic index, histological characteristics, and condition of Antarctic toothfish during winter to further refine the developmental cycle. Other secondary objectives are to investigate the potential dispersion of eggs and larvae by studying the characteristics of Antarctic toothfish eggs with regards to buoyancy and to investigate the timing of the movement of Antarctic toothfish to and from the spawning grounds through an analysis of length and age composition of the catch, sex ratio, fish condition, and stable isotopes.

New Zealand FV Janas conducted research in two research blocks (882A_5 and 882B_4) as part of a multi-year and multi-member research plan using standardised longline gear to sample toothfish populations in the northern areas (60°‑ 66° S) of Subarea 88.2 SSRUs A–B. Sampling strategy and data collection adhered to standards set in CM 41-10 (2014). A total of 49.85 t of Antarctic toothfish and no Patagonian toothfish were caught. Toothfish catch rates, size, sex ratio, and reproductive maturity status were similar to existing data from SSRU 88.1C. In contrast, the gonadosomatic index and the sex-specific Fulton’s condition factor observed in the northern region of SSRU 88.2B were lower than those observed in SSRUs 88.1C, northern 88.2A, and 88.2H. The percentage of fish with empty stomachs was high, but prey diversity and quantities of prey items were similar to those reported from the northern Ross Sea. Bathymetry data were collected during the survey and during transit across research blocks and have been provided to the CCAMLR Secretariat.

A research proposal to continue the southern Ross Sea sub-adult toothfish survey for the next two years, 2016–2017, is presented. The survey will continue to focus primarily on estimating the relative abundance of sub-adult (<110 cm TL) toothfish in the core strata (A, B, C) in SSRUs 88.1J and 88.1L. This is a continuation of the time series of CCAMLR-sponsored research surveys of these strata carried out from 2012–2015.

It is also proposed that the survey be extended to include adult toothfish in McMurdo Sound following the recommendations of WG-FSA (SC-CAMLR-XXXIII, Annex7, para 5.108) and Terra Nova Bay where substantial numbers of larger sub-adult and adult toothfish were captured in the 2015 survey. As it is less critical to survey these larger sub-adult and adult toothfish on an annual basis, it is proposed that these two areas be surveyed in alternate years. Therefore, it is proposed to survey McMurdo Sound in 2016 and to survey Terra Nova Bay in 2017.

Survey timing and methods will remain the same as in previous years, and the number of sets will be retained at 45 sets for the core strata but reduced to 10 sets for the McMurdo/Terra Nova Bay strata making 55 sets in total. A nominal catch limit of 40 tonnes is requested for each survey. It is envisaged that the results of the 2016 survey, and trends in the time series, be presented to WG-FSA for review in 2016 and that a full review be completed and presented to WG-SAM and WG-FSA in 2017.