CCAMLR

We report results of analyses of niche occupation among mesopredators in the Ross Sea region, Antarctica, considering three important components: 1) projected distribution and overlap across the surface of the ocean, 2) capacity to utilize differing amounts of the water column (foraging depth) and 3) diet. Species included were: Antarctic Minke Whale, Ross Sea Killer Whale (ecotype C), Crabeater Seal, Weddell Seal, Emperor Penguin, Adélie Penguin, Light-mantled Sooty Albatross, and Antarctic and Snow petrel. The apex predators, Leopard Seal and Killer Whale ecotype A/B, were not included because of their rarity and, therefore, lack of adequate sighting data on which to generate spatial models. We also did not have adequate data to model Arnoux’s Beaked Whales, Antarctic Toothfish nor Colossal Squid, which likely are also important mesopredators, particularly adult toothfish. We modeled mesopredator species distributions at a 5km/pixel scale, using environmental data and species presence localities from at-sea surveys and other sources. A machine learning, “maximum entropy” modeling algorithm (Maxent) was used to model spatial patterns of species’ probabilities of occurrence, and these data were used to identify areas of importance to species in a conservation prioritization framework (Zonation). Data on depth of diving and diet were taken from the literature. Three patterns of horizontal spatial use of the Ross Sea were apparent: 1) Shelf Break: restricted mostly to the shelf break, which includes outer continental shelf and slope (Light-mantled Sooty Albatross); 2) Shelf and Slope: full use of both the shelf and the slope (Ross Sea Killer Whale, Weddell Seal); and 3) Marginal Ice Zone (MIZ; pack ice surrounding the Ross Sea post-polynya): combinations in which the slope is the main habitat but western and eastern portions of the shelf (where sea ice is persistent) are used as well (Minke whale, Crabeater Seal, penguins, petrels). Diet composition overlapped extensively, but use of foraging space was well partitioned by depth of diving. Horizontally, the entire suite of mesopredators used the entire shelf and slope in a mosaic pattern although, not necessarily during the same season. Spatial modeling of species richness, supported by Zonation analysis, indicated the outer shelf and slope, as well as deeper troughs in the Ross Sea Shelf and Ross Island vicinity to be particularly important to the upper trophic level organisms of the Ross Sea. Our results substantially improve understanding of these species’ niche occupation previously only described using heuristic approaches.

This report provides the scientific basis, validating the results of the CCAMLR Bioregionalization Workshop (2007) as well as the report of ASOC (2010), for identifying the Ross Sea as one of 11 areas deserving close scrutiny for inclusion in a network of marine protected areas. CCAMLR (2007) identified the Ross Sea as an area of high biodiversity on the basis of its high physical heterogeneity; ASOC (2010) compared characteristics of the Ross Sea to areas designated under various international agreements instituted to preserve biodiversity. The CCAMLR (2007) subsequently was endorsed in the joint meeting of CCAMLR's Scientific Committee and the Environmental Protocol's Committee on Environmental Protection (ATCM XXXII-CEP XII, Final Report, 2009). Considered herein is the Ross Sea shelf and slope, which is a smaller portion of the area identified in CCAMLR (2007) as “Ross Sea shelf”. Waters overlying the Ross Sea continental shelf and slope comprise ~2.0% of the Southern Ocean, an area inconsequential in size from a global perspective. However, as shown by this summary of information — amassed from the national research programs especially of Italy, New Zealand, United Kindgom (during the “heroic” era), and United States — the Ross Sea not inconsequential is its biodiversity nor its disproportionate contribution to world populations of many well-known iconic Antarctic species. The data and information presented herein show that the Ross Sea:

The krill escapement mortality and the methods to determine it are closely connected with the need to have systematic observer coverage in the Antarctic krill fishery. Experiments to estimate krill escapement mortality should be introduced on all krill fishing vessels that carry scientific observers onboard. To provide krill escapement mortality experiments it is proposed that data on speed of trawling are added in form C1. It is proposed to add appropriate regulations to the Scientific Observers Manual and new suitable section to the Observer Cruise Report. The need to have observers collecting data on krill escapement mortality emphasizes the need to have a comprehensive observer program in place for the Antarctic krill fishery.

To support the implementation of both the precautionary and ecosystem approaches to the ongoing management of the Southern Ocean krill fishery, Norway would like SC-CAMLR and its Ecosystem Monitoring and Management Working Group to consider a proposal to obtain annual krill biomass information in CCAMLR sub-area 48.2.

Results of Russian krill fishery in the area 48.2 in the season of 2009 (March – beginning of June) on the cruise data of trawler “Maxim Starostin” are discussed in the paper. The vessel used the continuous fishing method. 21 trawlings with the total duration of 1113,5 hours were carried out during 71 fishing days. Mean catch per hour trawling is 5,6 t/h. Data on daily catch, catch per hour trawling, krill length composition and biologicall conditions along with description of hydrometeorological and ice conditions are given in the paper.

In accordance with conservation measures (CM) in force, Members are required to notify the Secretariat of encounters, and potential encounters with vulnerable marine ecosystems (VMEs). Notifications are made either under CM 22-07 in the case of encounters with potential VMEs during the course of bottom fishing, or under CM 22-06 in other cases such as during research surveys. The Secretariat received a total of 30 notifications of encounters with VMEs in 2008/09 arising from research surveys (CM 22-06); no new notification has been submitted so far in 2009/10. The encounters were notified from Subareas 48.1 (17 notifications) and 48.2 (11 notifications) and Division 58.4.1 (2 notifications), and the VMEs were observed using in-situ photography and benthic/bottom trawls. VME-indicator notifications have been submitted from the exploratory pot fishery for crab in Subarea 48.2 (1 notification), and the exploratory longline fisheries for Dissostichus spp. in Subareas 48.6 (1 notification), 88.1 (32 notifications) and 88.2 (19 notifications). A total of 53 notifications have been received, of which 29 were made in 2008/09 and 24 have been made so far in 2009/10. No notification has arisen from exploratory fisheries in Divisions 58.4.1, 58.4.2, 58.4.3a and 58.4.3b. Fifteen VME-indicator notifications reported  10 VME-indicator units recovered from single line segments. These notifications were made in Subareas 88.1 and 88.2, and resulted in the declaration of 15 risk areas. In addition, three VME fine-scale rectangles have been identified in these subareas.

Seven Members submitted notifications for a total 15 vessels for krill fisheries in Subareas 48.1, 48.2, 48.3 and 48.4 and Divisions 58.4.1 and 58.4.2 in 2010/11. There was no notification submitted for exploratory fisheries for krill in 2010/11. The total notified, expected level of catch of krill in 2010/11 is 410000 tonnes.

So far this season (2009/10), ten of the 11 krill fishing vessels licensed by Members (China, Japan, Korea, Norway, Poland, Russia) have fished in Area 48. The total catch reported to May 2010 was 108550 t, most of which has been taken from Subareas 48.1 and 48.2 between February and May. Approximately 40% of the catch has been taken by two vessels using the continuous fishing system. The forecast total catch of krill for the season is 150000-180000 t . In 2008/09, five Members fished for krill in Area 48 and reported a total catch of 125826 t; two vessels used the continuous fishing system. The largest catch of krill was taken from SSMU SOW (South Orkney West) in Subarea 48.2 (89184 t), and the remainder of the catch was taken predominantly in Subarea 48.1, notably 19691 t from SSMU APBSE (Antarctic Peninsula Bransfield Strait East) and 2745 t from SSMU APE (Antarctic Peninsula East). This is only the second time that fishing was reported from SSMU APE; previously, 25 t of krill was taken in 1995/96. The daily catching capacity of vessels in the fishery has increased markedly since 2003/04, with vessels using conventional trawls now capable of catching and processing up to 400 t of krill per day, and some vessels using the continuous fishing system have exceeded 800 t of krill per day.

This paper presents a time series of relevant data reported from scientific observations in the CCAMLR krill fishery: 1999/2000 to 2008/09.