The subject of research was geostrophic circulation of water masses, spatial distribution of krill density, intensity of water flows (m³/s) and krill biomass (g/m³) transported by water flow at various spatial-temporal scales in the Scotia Sea. According the discussion at WG-EMM-2018 (paragraph 2.24-2.27), particular attention is paid to the special field studies across time to improve understanding of krill biomass dynamic. It has been shown that the formation of transport of krill in the Scotia Sea requires both favorable dynamic conditions and krill influx from the Antarctic Pacific and the Weddell Sea.
The data obtained demonstrate that the dynamics of krill biomass in a given area is more dependent on the intensity and structure of krill transport over, and is not determined by the state of the local stock of krill and, especially, by the effect of the fishery on krill resources. The variability of fishery indices, also to a greater degree, is a reflection of the spatio-temporal variability of the processes of krill flux through the area of operation of the fleet.
Risk assessment of fishery management requires adequate data on variability of biomass distribution and population structure of krill under the influence of its drift at various spatial-temporal scales.
Abstract:
The key issues for development of krill fishery management schemes based on the ecosystem approach and proposal to generate baseline data in the context of addressing these problems are considered.
Abstract:
The issues are discussed on estimating spatial-temporal distribution of krill length composition in Subarea 48.1 as the essential information for stock assessment and developing management advice.
Abstract:
Methodical aspects of a large-scale international survey in 2019 are discussed in the context of stated objectives. The main sources of uncertainty in the results of the 2019 survey are shown.
Abstract:
Accurate census counts are fundamental to population management, but can be challenging to obtain in remote polar environments. The standard approach for income breeding pinnipeds, such as the Antarctic fur seal (Arctocephalus gazella), is to annually survey pup production. Fur seal population dynamics in the South Shetland archipelago are largely driven by two breeding colonies, Cape Shirreff and the Saint Telmo Islands. Although annual counts have been undertaken at Cape Shirreff since the 1990’s, logistical challenges have prevented surveys of the St Telmo Islands since 2008. Over the last decade unmanned aerial systems (UAS), or drones, have become indispensable tools for wildlife monitoring. We used a medium-range vertical takeoff and landing (VTOL) UAS to obtain pup counts from the St Telmo Islands during the 2018-19 field season. The APH-28 provided a minimally-invasive, robust, and accurate (error rates <2%) survey tool. The corrected 2019 census count from the St Telmo Islands was 333, which represents a 79% reduction since the most recent survey in 2008, and a 90% reduction from the peak of recent production in 1997. Given the historical importance of Cape Shirreff and St Telmo to the AFS population dynamics in the South Shetlands archipelago, these declines emphasize the need to synoptically survey all known and potential breeding sites across the South Shetland Islands as soon as is practicable.
Abstract:
India is getting prepared to take up studies on Krill associated ecosystem studies in the Western Indian Ocean sector of the Southern Ocean, through in-situ ship survey in the area during Austral summer 2019-20. The proposed objectives are to to understand the distribution and biomass of krill in the western Indian Ocean Sector of the Southern Ocean, to relate larval/adult krill with the prevailing oceanographic/environmental set-up, to examine the spatial pattern of the resource and the forcing and response functions that regulate the distribution, ultimately, to explain the impact due to change in climate or long term variations. Special emphasis will be given on the regional ecosystem processes encountered along the two meridional transects which National Centre for Polar and Ocean Research (NCPOR), India is being monitored regularly.
Abstract:
While fishery-dependent data represents the preferential way to collect geographically spreadtime series of data to study the Antarctic toothfish, it is limited to areas where commercial fishing is permitted either by management or vessel operational constraints. The use of Baited Remote Underwater Video (BRUV) allows a solution to this problem. Thanks to the collaboration between New Zealand and Italy, from 2015 to 2018 a series of BRUV samplings have been carried out from the fast ice of McMurdo Sound and Terra Nova Bay, in the southwestern Ross Sea. Here we report a methodological approach to obtain from the videos recorded information on abundance and size distribution related to a series of predictive variables, including an approach to account for bias in counting the number of individuals attracted to the bait. Because we are now focussed on developing the method, the results are preliminary. The aim of the paper is to disseminate to the Members the methodology that we have used. Once refined, our hope is that it could provide a mechanism for other Members to extend the area of data collection and better understand Antarctic toothfish distribution in shelf areas under the ice.
Abstract:
Resource competition often results in mechanisms that ameliorate its effects, typically through the partitioning of resource exploitation either temporally or spatially. Understanding the spatial and temporal overlap between predators that exploit the same resource then is fundamental to understanding the impacts one predator can have on another. The fishery for Antarctic krill operates along the west Antarctic Peninsula and the Scotia Sea, and while there are calls for its expansion there is a concern that any increase in catch levels should not result in long-lasting or irreparable damage to the ecosystem. Considering the fishery as another krill predator then, it follows that understanding how it functionally overlaps with other krill predators such as seals, whales and seabirds is critical. Similarly, characterizing the competitive interactions between these species is key to disentangling the drivers of functional responses of each species. We highlight this by collecting at-sea habitat use of adult male Antarctic fur seals which move into the Bransfield Strait and southern Scotia Sea during the austral summer and remain there throughout the winter. We identify considerable spatial and temporal overlap with breeding Chinstrap penguins in the Bransfield Strait at a time when fishing effort is minimal, as well as when effort is at is maximum at the South Orkney Islands. We recommend that this overlap should be considered in understanding the functional response of penguins and suggest that male AFS could be a useful monitoring taxon given its lack of post-breeding spatial constraint, its numerical abundance and the relative ease by which data could be collected.
Abstract:
Norwegian Polar Institute led a cruise to the Kong Håkons VII Hav 28th February -10 April 2019. Our focus area was the ocean south of 65°S east of 0° meridian and 13.5° E (Fig 1) with a focus on Astrid ridge. Our focus was to map and describe the whole ecosystem. During transit, we registered birds, seals and whales systematically and registered krill and fish abundances using echo sounder. At different depths, we ran ROV transects filming and retrieving samples for later species identification. The ROV transects made up the basis of our intensive study areas. Each intensive study area contained in addition to the ROV transect, benthic sampling with appropriate gear, fish and krill trawling, long line and 3-4 CDT station with extensive water sampling for primary production and water chemistry. We rad oceanographic sections across and along the Astrid ridge and at 6,2° E. Due to heavy ice we did get to 69.5° S and depths of about 1100m.
Crossing the deep ocean along 86.1°S we encountered an extensive algae bloom in the deep trench separating Astrid ridge and Maud rise. Associated with the algae bloom we had large concentrations of krill, humpback whales and birds. We found some large concentrations of krill in the pack ice over Astrid ridge with few whales around. Far south on Astrid ridge we encountered some flocks Emperor penguins and Antarctic petrel and Snow petrels were abundant. Of the seals, mainly Crabeater seals was seen and no Weddell seals was spotted.
On Astrid ridge the ROV and bottom trawls found that Echinoderms and shrimps were dominating the transect. Holothuroids were especially abundant and included at least five different species. We set three longlines and got only four tootfish, all at Maud rise. The results from the CTD samples are still being analyzed and no conclusions are made.
Most of the samples are still being processes so any results must be used with caution.
Abstract:
Preliminary results from the International Synoptic Krill Survey in Area 48, 2019, are presented. Of the six vessels that participated in the survey, this report provides methods and preliminary results from four (vessels from the Association of Responsible Krill harvesting companies (ARK), Norway, Ukraine, and the United Kingdom), covering 8719 n. miles of acoustic transects and occupying 149 sampling stations. Acoustic transects and trawling were carried out as per survey procedures developed in 2018, which were based on the methods and procedures used in the CCAMLR 2000 krill acoustic survey. Backscatter from krill were delineated using the 'swarms' method and integrated to produce distribution maps of krill NASC (nautical area scattering coefficient). A preliminary spatial cluster analysis of krill length distributions was undertaken to assist with calculating the acoustic target strength values needed to convert krill NASC to biomass. Further integration of data from all survey vessels and standardisation of analysis procedures are planned to be done in conjunction with the upcoming SG-ASAM meeting in August 2018.