Vessels operating in the krill fishery in CCAMLR’s Convention Area are required to directly estimate the green weight of krill caught (Conservation Measure 21-03, Annex B). This requirements was introduced for the 2012/13 seasons, and the estimation methods were revised at WG-EMM-13 and WG-EMM-14. Estimates of green weight and parameter values are reported in each vessel’s haul-by-haul catch and effort data (C1 data).

Vessels fishing in 2014/15 used five methods for the direct estimation of the green weight of krill caught: codend volume, holding tank volume, flow meter (method 2), flow scale and meal conversion.

This paper provides a preliminary summary of the data reported so far in 2014/15 (to May 2015).

Annual acoustic trawl surveys for krill monitoring have been carried out by the Institute of Marine research, Norway near the South Orkney Islands since 2011. The survey has been conducted early in the fishing season (January/February), using two different krill fishing vessels as platforms. The vessels were equipped with similar Simrad echo sounder systems suitable for quantitative assessments, but the frequencies operated varied between vessels and years. In addition, the survey coverage has varied between years in particular due to ice. In order to allow for comparison of distribution and abundance of krill near the South Orkneys among years, we here attempt to generate a coherent series of krill density estimates from the 5 years of surveys. We follow the CCAMLR protocol for biomass estimation as far as practically possible, given that we work with unconventional sets of frequencies for target strength estimation and target identification. In order to avoid variability due to differences in coverage, we also define a stratum within the survey area on the north side of the islands with full coverage in all years except 2013. The results show that except from the year 2015, krill densities were high, in the range 100-300 g/m² based on the 120 kHz recordings, and a total estimated biomass of ca. 8 million tons of krill within the stratum in the peak year 2014. There were also consistently higher values of acoustic backscatter on the north side of the islands where the fisheries occur, than on the south side. Values were particularly high in the north-west shelf area associated with underwater canyons. In 2012, and particularly in 2015, low proportions of the acoustic backscatter were allocated to krill. The low proportions are probably caused by shortcomings in the krill identification techniques when other pairs of frequencies than combinations of 38, 120 and 200 kHz are used.

Between 2001 and 2013 the number of breeding pairs of Adélie penguins (Pygoscelis adeliae) at breeding colonies in the southern Ross Sea more than doubled from about 235 000 to more than half a million. It has been suggested that predation release of Antarctic silverfish (Pleuragramma antarctica) due to fishing of one of its predators, Antarctic toothfish (Dissostichus mawsoni), could have contributed to the increase in Adélie penguin numbers. This paper brings together information on the biomass, consumption rates and diets of toothfish and Adélie penguins over the Ross Sea shelf as a first test of the predation release hypothesis. In particular, the examination of 422 Antarctic toothfish stomachs showed that they consume only a small proportion of silverfish (1.9–5.1% by mass) over the southern Ross Sea shelf. These Antarctic toothfish were sampled over three years, between 2011/12 and 2013/14. The mass of silverfish estimated as being released from predation by fishing (577 tWW/y) was equivalent to about 2% of the amount of silverfish consumed annually by Adélie penguins in this region. This result was inconsistent with predation release of silverfish due to the toothfish fishery being responsible for recent increases in the number of Adélie penguins breeding in the southern Ross Sea. Mixed trophic impact (MTI) analysis was used to look for alternative indirect pathways through the food-web by which changes to toothfish could affect Adélie penguins in the Ross Sea. The MTI analysis found only a weak link between changes in toothfish biomass and changes to the biomasses of silverfish and Adélie penguins. Essentially, Antarctic toothfish and Adélie penguins were not assessed as having overlapping diets over the Ross Sea shelf: Antarctic toothfish consume mainly small, bottom-dwelling fishes (especially icefish, and Trematomus spp.) while Adélie penguins consume crystal krill and silverfish in the water column. The large-scale trophic connection between toothfish and Adélie penguins over the Ross Sea shelf is hence weak. We encourage the development of further specific hypotheses of mechanisms by which fishing could affect Adélie penguins in the Ross Sea.

We present definitive evidence, derived from two independent methods (satellite tagging and photo-identification), that TCKW undergo long-distance travel from the southern Ross Sea to New Zealand waters and into subtropical regions (31°-35°S). This not only establishes ecosystem connectivity between the Ross Sea and New Zealand, but also emphasises the urgent need to re-evaluate the profile of potential threats faced by, and capacity for resilience in, this top predator. Together with Weddell seals, TCKW have been identified as one of the two top predator species in the Ross Sea most likely to be affected by the Ross Sea fishery for Antarctic toothfish, Dissostichus mawsoni, but critical knowledge gaps regarding abundance, diet, foraging habitat, and movement patterns limit our ability to assess or manage risk to TCKW.

New results from satellite transmitters deployed on TCKW in Terra Nova Bay suggest that TCKW may use small-scale areas in this highly productive ecosystem intensely for a period of days to weeks, but also undergo rapid long-distance travel along a northward transect towards New Zealand and the Kermadec Trench. Dive records from these tagged TCKW (n=4) indicate that whales perform deeper dives while in Terra Nova Bay (100-455 m) than on the northbound journey. A preliminary analysis of photo-ID data indicates that TCKW show a high degree of seasonal site fidelity, with whales inter-annually returning to areas of ecological significance, including New Zealand waters north and east of East Cape, the Kermadec Trench region, and highly productive Antarctic areas providing access to silverfish and toothfish (or other, yet unidentified prey resources).

The unexpectedly complex movement patterns and extremely broad spatial scale of movement exhibited by TCKW have important implications for our understanding of the ecology of this key Ross Sea predator, and for the precautionary spatial management of the Ross Sea regions, including monitoring of the existing ASPA #173 Silverfish Bay and the establishment and ongoing monitoring of the proposed Ross Sea Marine Protected Area.  These research priorities would be best addressed by multi-national collaborative efforts coordinated through the frameworks of IWC SORP and CCAMLR.

An integrated assessment model for Antarctic krill in FAO Subarea 48.1 that incorporates catch and length-composition data from the krill fishery with biomass indices and length-compositions from research surveys has been developed. The model uses statistical fits to these data to estimate the effects of the fishery on the krill population. The model estimates parameters representing krill population biology and the fishery during the period with data (1976 to 2014 in these models) and then applies these parameter values to future projections (2015-2034) at pre-specified levels of future catches. The model can compare predicted krill spawning biomass expected with projected future catches to the CCAMLR decision rules. An alternative pair of decision rules to those currently employed by CCAMLR are also applied to the projections. The alternative rules are based on comparing krill spawning biomass expected under projected future catch levels to spawning biomass expected without any fishing during the same future period. The CCAMLR rules are based on comparisons to estimated pre-exploitation spawning biomass instead of to projections with no fishing. Catch levels that meet the various decision criteria are identified and compared. Arbitrary time-series of future annual recruitments may be supplied to the model. Example estimates of spawning biomass for different future levels of catch, assuming recruitment in the future will be the same as recruitment estimated during the period for which survey and fishery data were available, are reported. The effects of using different data sources and weightings on the estimates of stock status during the estimation period are explored.

The importance of Unmanned Aerial Vehicles (UAVs) in remote sensing is rapidly growing. However, knowledge about their potential impact on wildlife is scant, especially in the Antarctic, where they are a new tool used in ecological research and monitoring.   

In this preliminary study we investigate potential effects of wildlife disturbance by UAVs. In austral summer 2014-2015 UAV overflights were conducted, in the Adelié penguin (Pygoscelis adeliae) colony at Pt. Thomas (Western Shore of Admiralty Bay, King George Island, Antarctic, subarea 48.1). The impact of electric and combustion engine UAV flying at the altitude of 300-350 m AGL (Above Ground Level) over the colony were compared to undisturbed colony, and to natural disturbance (skua Stercorarius sp. flying over nesting penguins). Penguin behavior was divided into: resting behavior, comfort behavior, vigilance/anxiety and aggression. Percentages of birds exhibiting different types of behavior, time spent on each type of behavior and number of different types of behavior displayed by one bird during the observation periods were compared. No differences were found between control and overflights by electric UAVs. During the overflight by UAV powered by combustion engine, symptoms of vigilance were noticed with penguins looking up and around for a few seconds when UAV was overhead. Similar symptoms of vigilance were observed when skua flew (aprox. 5 m AGL) over penguin colony without trying to attack nesting birds. No increase in aggressive behavior was observed during the overflights. Plans for a systematic monitoring of UAV impact on wildlife, as well as preliminary guidelines for the next field season were formulated.

Dynamic climate changes have become noticeable in recent decades, especially in the vulnerable region of Western Antarctic. The relatively simple food web of this area relies on krill - Euphausia superba. Presumably as a result of climatic fluctuations, a decrease in the numbers of this crustacean has been recorded, followed by an increase in the population of the gelatinous zooplankter Salpa thompsoni.

In the inquiry herein presented, population and morphometric analyses on Salpa thompsoni have been conducted. Specimens for this research were collected from the Drake Passage, using a Bongo net in the summer season of 2010.

It has been found that the horizontal distribution of this gelatinous zooplankter was significant irregular (Kruskal-Wallis test, p<0.001). In the northern part of the investigated area both blastozooids and oozooids were recorded, which confirms the dynamical performance of this species’ development. The central part of the Drake Passage was characterized by a dominance of blastozooids, with embryos found in different stages of development. Only in the region of South Shetland Island was the Salpidae population characterized by slowed, or even stopped reproduction.

The immense reproduction efficiency observed in the Salpa thompsoni population was mostly induced by beneficial thermal conditions. These observations may suggest that ongoing environmental changes in Western Antarctic will promote expansion of this species’ population.

An integrated, age-structured model was fitted to different combinations of survey data using two forms of selectivity (logistic or double-logistic) with time-constant or annually varying selectivity to investigate the population dynamics of Antarctic krill (Euphausia superba) near the Antarctic Peninsula. The data were from surveys conducted by the U.S. Antarctic Marine Living Resources Program around the South Shetland Islands from 1992 to 2011. Two indices of krill biomass based on (1) trawl-net samples and (2) hydroacoustic sampling were combined with length-compositions from the nets. Sixteen model configurations using different combinations of the two biomass surveys with the various options for modeling selectivities were examined. Parameters were estimated in phases with the sequential order of the phases randomized until an invertible Hessian matrix was obtained. Model consistency for the estimates of derived quantities was tested using simulated data. Annual trends in the estimates of total biomass, spawning biomass, and recruitment were similar among different configurations assuming time-constant selectivity, but the absolute scaling ranged widely depending on which biomass indices were used. All configurations with time-constant selectivities were able to reproduce the derived quantities of the operating model when fitted to simulated data. Annually varying selectivities produced more variable estimates of the trends in population biomass, but less variable estimates of scale, compared to time-constant configurations fitted to the same data. The models with annually varying selectivities did not produce invertible Hessian matrices, and four of these configurations could not reproduce the derived parameters of their operating model when fitted to simulated data. Using AIC, the model with logistic, time-constant selectivities was selected as the best configuration to fit both sources of biomass data. The two-stage approach of first randomizing the phase order until an invertible Hessian matrix is achieved and then verifying the reproducibility of the estimates of derived quantities using simulated data could be employed in any integrated stock assessment with parameters estimated in phases.

Unmanned Aerial Vehicles specially adapted for operation in polar regions were used to study distribution and size of three Pygoscelis penguin species on King George Island (Subarea 48.1) in the austral summer 2014/15 season. During photogrammetric flights the high-resolution images of the penguin breeding colonies were taken. Obtained images were used for estimation of population size and compared with the results of measurements taken at the same time from the ground level. During expedition eight successful photogrammetry missions (total distance 1500 km) were performed. Images were taken with digital SLR Canon 700D, Nikon D5300, Nikon D5100 with a 35mm objective lens. Flights altitude at 350 – 400 AGL (Above Ground Level), allowed images to be taken with a resolution GSD (ground sample distance) less than 5 cm. Precision estimation of individuals count was based on the photo interpretation of images. The use of UAV for monitoring of indicator species, enabled data acquisition from areas inaccessible by ground methods.