CCAMLR

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.

Nueva Zelandia ha contribuido activamente al proceso de planificación de AMP de la CCRVMA, y junto con Estados Unidos presentó al Taller sobre AMP de la CCRVMA el documento de trabajo WS-MPA-25 (Sharp y Watters 2011), con el borrador de Nueva Zelandia de un sistema de AMP para la región del Mar de Ross. Este documento presenta el bosquejo de Nueva Zelandia y el método de planificación utilizado para desarrollar el sistema, y proporciona la información complementaria solicitada por el Taller sobre AMP de la CCRVMA, para que sea considerado por el Comité Científico.

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.

The present paper presents the brief results of the research in reproductive biology of the Antarctic greinadier M. whitsoni in the Ross Sea. It was stated that the eggs were released by batches. It was supposed that the similar character of spawning might be for some other Antarctic fish species. Some peculiar features of the reproductive biology Moray cod M. evseenkoi, Antarctic toothfish D. mawsoni and other fishes are provided.

In 2010, two toothfish species, Patagonian (D. eliginoides) and Antarctic (D.mawsoni) toothfish, were registered during the fishery on Dissosyichus spp. on the shelf edge and slope of Bouvet Island. Their commercial concentrations were found also on the neighboring underwater plateaus surrounding the island. The vertical distribution of two species was differentiated distinctly, with the crossover point at depth of 1300 m. For both species the size and weight compositions were studied; indices of stomach fullness and qualitative diet composition as well as maturation stages of gonads and their weight were determined; gonadosomatic indices (GSI) were calculated. The sex ratio in catches and vertical distribution of toothfish in the fishing area were analyzed also.     
 

In 2010 on the southern slope of Bouvet Island, I found L. kempi at still greater depth in the course of fishery for toothfish onboard of 1 Insung Korean longliner. In the first case, mature specimens with absolute length (TL) of 39–45 cm and weight of 0.8–1.3 kg
were found in stomachs of Antarctic toothfish caught at depths of 1500–1900 m. In the second case at 54°32′7 S and 03°46′8 W, three specimens of striped-eyed rock cod were caught (one female and two males) at a depth of 2033 m.