CCAMLR

The integrated assessment of Patagonian toothfish, Dissostichus eleginoides, for the Heard and McDonald Islands (Division 58.5.2) was updated from WG-FSA-09/20. The main change other than updating total removals by sub-fishery and updating catch-at-age and catch-at-length proportions was the inclusion of random stratified trawl survey (RSTS) abundance-at-age for 2010 and 2011 and conversion of 2008 and 2009 RSTS abundance-at-length to abundance-at-age. This was possible due to the large number of otoliths collected and aged for each annual RSTS since 2008. Catch-at-length proportions for the commercial fisheries, both trawl and longline, were used for 2009 to 2011 since there were few fished aged for these years. A series of standardised longline CPUE data from one of the longline grounds (or subfishery) which has been consistently fished since 2003 was added for the first time. All three of the standardised CPUE series have minimal influence on the model parameter estimates due to the large degree of uncertainty about annual estimates but given this caveat they are useful in tracking observed and CASAL-estimated trends in catch rates.
A change of substantial consequence from the 2009 integrated assessment was the use of a value for natural mortality (M) of 0.155 whereas a value of 0.13 was used previously. Neither of these values of M was estimated in CASAL but the value of 0.155 was estimated externally to CASAL from catch-at-age and aged mark-recapture data as described in Candy et al. (2011). The consequence of using a higher M in the integrated assessment was a reduction in the estimate of B0 with a compensatory increase in R0. Using the same data as the 2009 assessment the reduction in B0 was 33.1% and the increase in R0 was 23.5%. For the updated assessment with M set to 0.155 the corresponding percentage change relative to the 2009 assessment were 25.8% and 36.9%, respectively. Since the trawl fishery, and to a lesser degree, the longline fishery catch relatively few fish that are at an age to begin spawning or older (i.e. mostly above age 14), the higher recruitment despite the higher M meant that a similar but slightly higher long-term yield was estimated for the updated assessment to that in 2009.
For the updated assessment, the long-term yield that satisfies the CCAMLR decision rules is 2 730 t.
 

In 2011 data on beach surveys, debris associated with seabird colonies, marine mammal entanglements and hydrocarbon soilings were received from South Africa, the United Kingdom, and Uruguay.  Non-fishing items such as packaging and wood remain the most common type of debris items found in beach surveys.  The fishing items found were mostly from longline origin. Plastic packaging bands continue to be found in beach surveys with closed bands found at Bird Island (1) and King George Island (3), despite Conservation Measure 26-01 requiring packaging bands to be cut up into 30 cm pieces.
The amount of debris in colonies of grey-headed albatrosses and black-browed albatrosses at Bird Island has increased recently, and the major category of items found was plastics.  The amount of fishing related items (fishing lines and hooks) found in wandering albatross colonies remains the foremost debris item found in each season.
The number of marine mammal entanglements increased in 2011 with packaging bands and fishing gear the main entangling materials.
There was only one new hydrocarbon soiling reported from King Edward Point in 2010.  
The reported hook loss from the longline catch and effort data shows that while it is a small percentage of the total hook set, it is a considerable amount of gear that is lost in the water.
 

Random stratified trawl surveys were completed in September 2010 and in March to May 2011 on the RV Southern Champion, adding to the time series of annual surveys in Division 58.5.2 that commenced in 1997. An earlier survey in April 2010 was not completed, but valid hauls from this, as well as the September 2010 survey were used in the stock assessment as they provided valuable additional information on abundance. Catches of D. eleginoides were at half or lower than in surveys from both years than the average catch for the previous four years (2006-2009).  Catches of C. gunnari were very low, with the 2011 catch, at less than 0.5 t, 15% of the earlier four year average, and the 2010 catch being 60% of the 2011 catch. In 2011 the abundance of L. squamifrons was higher, and C. rhinoceratus lower than the average. Macrourid catches have been stable over recent years, with a fall in 2011. Skate catches were just below and just above average for 2010 and 2011 respectively. A notable increase in the catch of invertebrates was reported in the 2010 survey, consisting mostly of poriferan sponges, anemones and sea stars. The 2010 catch was 2.5 times higher than the 2006-2009 average. Invertebrate bycatch returned in 2011 to a level more common in previous years, dominated by asteroids, anemones, ascidians and poriferans. This data will be incorporated into models being developed at the AAD to predict the location of vulnerable benthos. An analysis of numbers and biomass of young toothfish estimated from the survey area from 2001 to 2011 found no significant trends in abundance.

Surveys of mackerel icefish, Champsocephalus gunnari, was undertaken in Division 58.5.2 in the vicinity of Heard Island during September 2010 and April 2011, to provide information on the population dynamics of this species, and to provide a basis for an assessment of short-term annual yield in the 2011/2012 CCAMLR season. This paper provides a preliminary assessment of yield for the area of Division 58.5.2 to the west of 79o 20’ E using standard CCAMLR methods. A predicted in 2010, the strong 4+ cohort that dominated the population declined rapidly in late 2010. Two new cohorts are present in the population, leading to a situation that is unusual for this region, with four or five successive year classes all present simultaneously. A catch limit of 103 t is recommended for the 2011/12 season.

La Nouvelle-Zélande contribue activement au processus de planification des AMP de la CCAMLR et, avec les États-Unis, a soumis à l'atelier de la CCAMLR sur les AMP le document WS-MPA-25 (Sharp et Watters 2011), dans lequel figure le projet néo-zélandais de scénario d'aire marine protégée pour la région de la mer de Ross.  Le présent document décrit le scénario néo-zélandais et la méthode de planification par laquelle il a été établi, et fournit les informations complémentaires demandées par l'atelier sur les AMP de la CCAMLR à l'intention du Comité scientifique. 

In order to assess the level of confidence in the link made, as well as the time and effort  taken to make the link, the Secretariat introduced a tag recapture link status code to identify the level of effort involved in linking a tag recapture to its tagging event.  For the 2011 season 673 tags have been returned;  37% provide an exact match with tag numbers  held in the database, 22 % provide an exact match with tag numbers but had inconsistent ancillary data . For those tags that did not provide exact or unique matches only 63 (9%) could not be successfully linked using additional information.

An investigation into use the length-weight relationship of Dissostichus eleginoides and D. mawsoni to separate the two species was undertaken using data from the CCAMLR Scheme of Scientific Observation. Although the ability to discriminate the two species using length and weight measurement was inconclusive the process provided an opportunity to examine the variation in biometrics of both species by sex and by area and revealed some areas for future analysis.

A generic spatially-explicit age-structured model framework is in development that will enable to evaluate data collection protocols, assessment methods and management strategies. The model framework is programmed in R to promote transparency and interactions between researchers. It is based on the FLR framework and will incorporate links to external assessments programs such as CASAL. The model framework will have a number of modules representing the fish population dynamics, harvest by fishing fleets with different gear types or metiers, sampling of data, stock assessment, and implementation of fishery management decisions.
 

We used stable isotope and trace element chemistry from otoliths to test whether silverfish (Pleuragramma antarcticum) are distributed in independent, discrete populations in the Ross Sea, over the West Antarctic Peninsula, and around the South Orkneys; or whether the Southern Ocean circulation leads to connectivity. Otolith chemistry showed strong heterogeneity indicating four separate populations: i) in the Ross Sea, ii) on the southern Antarctic Peninsula in Marguerite Bay and off Charcot Island, iii) off Joinville Island, and iv) around the South Orkney Islands. This suggested that silverfish are not transported by the Antarctic Circumpolar Current, shelf processes on the West Antarctic Peninsula, or along the Weddell Front. However, the otolith chemistry combined with particle simulations suggested fish from Marguerite Bay may be advected along the southern Peninsula to Charcot Island by the Antarctic Coastal Current.