CCAMLR

Variability is a key feature of the pelagic ecosystems of the Southern Ocean and an important aspect of the variation is fluctuation in the abundance of krill, the major prey item of many of the higher predators. Direct impacts of variability in the large-scale physical environment, such as changes in ocean circulation, have been suggested as the main factor generating the observed fluctuations. So far, however, there has been little quantitative assessment of the importance of krill population dynamics in the observed variation. Here, analyses of a model of krill population development and predator diet data from South Georgia were used to examine seasonal changes in the population structure of krill. The krill population model was combined with a size-based selection function and used to generate expected length-frequency distributions in the predator diet through a summer season. Comparison of the model solutions with the predator diet data indicates that the model can reproduce the observed pattern of variation and emphasizes that adult population changes are a key aspect of the interannual fluctuations observed during some years. Low krill abundance was associated with reduced representation of the 3+ age group, whereas when krill were abundant the 3+ age class was the major age group present. The seasonal changes in the population structure in the predator diet involve a complex interaction of relative year class strength, timing of immigration, fluctuations in growth rates and dynamic predator selective effects. Development of the model to examine the interactive effects of changing krill growth and mortality rates will be a valuable next step. The dominance of the changes in krill population age structure underlines the fact that to understand the variability of the South Georgia ecosystem we must identify the major factors generating variability in population dynamics throughout the Scotia Sea.

This paper discusses the principles required to develop of small-scale management units and highlights a work program in this development. It provides the theoretical foundation for considering the scales of management units involving the integration of local populations of harvested species, foraging areas of predators, fishing grounds and the potential influences of the environment, including oceanography and metapopulation structure of the harvest species. The integration of these three components requires two different units: the “harvesting unit”, which is at the scale of the metapopulation of the harvested species, and the “predator unit”, which does not have to be a relatively self-contained ecosystem but should be sufficiently self-contained such that fishing in that unit does not inadvertently affect predators being monitored in other units. Harvesting units are defined and a number of additional divisions of CCAMLR statistical areas are proposed on ecological grounds to complete the division of the CCAMLR area. The South Atlantic region (Area 48) is used to illustrate how to define predator units. The derived conceptual model is then used to formulate a work program for the development of fisheries on prey species, notably krill, in other harvesting units. The manner in which predator units can be used to help the CCAMLR Ecosystem Monitoring Program provide strategic advice on the effects of fishing is discussed. In general, the early acquisition of information from within a harvesting unit on the distribution of local populations of krill, the potential foraging density of predators (i.e. abundance of predators, distribution of colonies and foraging range) and the potential fishing grounds will provide the means for circumscribing predator units as well as undertaking an assessment of long-term annual yield. It is proposed that the early development of the fishery could be concentrated in a small number of units to the extent that the fishing intensity in those units is equivalent to the intensity expected across all units once the TAC had been reached. Other units in which fishing was not occurring could be monitored as well. This process could help predetermine whether or not the TAC is likely to cause undesirable effects on predators in any of the predator units. In this way, the need for whether or not local restrictions on harvesting are necessary can be determined well in advance of the TAC being reached as well as the overall requirements for the monitoring program.

A proposal to arrange a CCAMLR course in survey design and execution at KMRS is put forward to propagate the experiences gained in planning and executing the CCAMLR 2000 krill survey. The proposed course would recruit teachers and students from member countries and illustrate both theoretical and practical aspects of krill survey work by planning and performing a “miniature survey” in Gullmarsfjorden with the Nordic Krill Meganyctiphanes norvegica as a model organism. It is argued that such an international course would help to assure that the collective wisdom of CCAMLR is maintained, developed and disseminated to younger scientist.

Scientific observations on fishes incidentally caught during commercial krill fisheries by F/V Niitaka Maru (3910t) were made from 16 December 2000 to 26 January 2001 in the vicinity of the South Shetland Islands. Among 103 net hauls quantitatively examined, by-catch fishes were found in 41 trawl catches. Lepidonotothen larseni was the most abundant in number and weight and occurred in 20.4% of hauls sampled for by-catch and 51.2% of those contained fish. P. antarcticum and C. gunnari were the second in abundance in number and weight respectively. Most hauls were dominated by one species which constitute 63.4% of hauls contained by-catch fish and a high degree of spatotemporal dissociation among juveniles of different species was recognized. The by-catch data of the present survey provided a clear picture of the negative correlation between abundance of by-catch fish and the krill CPUE. The relationship between towing time and estimated individual number of by-catch fish in each haul was obscure.

Cape Shirreff and San Telmo Islets (SSSI Nº32) shelter the largest breeding population of Antarctic fur seals, Arctocephalus gazella, in the South Shetland Archipelago. Since all censuses up to date have been single counts and do not allow the calculation of confidence limits, a protocol was developed for assessing uncertainties in the estimates of the counts (inter and intra-observer error) and put into practice during the 2000/2001 field season. Intra-observer error was between 0,15-1,74%CV, while inter-observer error was within 3% of the overall mean. The relationship between census error and pup numbers show a linear trend, however, some outliers (outside the 95%CI) could be identified and corresponded to beaches in which variation cannot be entirely attributed to inter-observer error. It can be suggested that topography, density, tides and meteorological conditions can affect pup censuses in a considerable way. These factors should all be assessed and taken into account when undertaking regional surveys of land-based predators in the future. Censuses developed at the SSSI have proved to be quite precise and this suggests that previously reported trends are not an artifact of counting error, thus supporting the hypothesis that the A. gazella population at SSSI Nº32 is reaching stability since more than 87% of K has already been attained.

A serological study was initiated to determine the presence of anti-Brucella antibodies on marine mammals of Antarctica. For this study, blood and extra vascular fluid samples was taken from 12 Weddell Seals (Leptonychotes weddellii) at the Site of Special Scientific Interest (SSSI) Nº 32 and CCAMLRa Ecosystem Monitoring Program (CEMP) site N° 2 “Cape Shirreff and San Telmo Islets” (62º 47’ S; 60º 27’ W), located on the Livingston Island (South Shetland Islands), Antarctica. Field work was carried out as part of Project 018 "Ecological studies on the Antarctic Fur Seal, Arctocephalus gazella" of the “Instituto Antártico Chileno” (INACH) and the laboratory analysis at the Departamento de Medicina Preventiva Animal, Facultad de Ciencias Veterinarias y Pecuarias of the Universidad de Chile.
The samples were tested by the conventional Rose Bengal test (RB) and two competitive enzymatic immunoassay: Compelisa®?(Veterinary Laboratories Agency, UK) and c-ELISA (FAO/IAEA, 1994). In five of the total samples studied, anti-Brucella antibodies were detected and the enzyme linked immunosorbent assays (Compelisa®) were the most sensible tests.
These results strongly confirm the presence of infections by bacteria of the genus Brucella in L. weddellii and point out the necessity of complementary studies to know the etiology and their infection epidemiology in this region of the world.

This paper describes the first detection of Brucella sp. antibodies in seals from the Antarctic territory. Sixteen antarctic fur seal (Arctocephalus gazella) and one Weddell seal (Leptonychotes weddellii) sera were tested by the Rose Bengal test (RBT), complement fixation test (CFT), immunodiffusion (AGID) and c-ELISA. Antibodies against Brucella sp. were detected with the RBT, the CFT and the c-ELISA in six of the seventeen samples involving the two animal species. It is concluded that a Brucella sp. described as affecting marine mammals in the Northern hemisphere could be also present in the Antarctic territory.

The US AMLR Program conducted large area surveys in the Elephant Island-South Shetland Island region during 18-30 January 2001 (Survey A, 101 stations) and 12 February-12 March 2001 (Survey D, 96 stations). Krill, salps and other zooplankton were collected at each station using a 180 cm Isaacs Kidd Midwater Trawl fitted with 505um mesh nets. Data obtained from these surveys were compared to assess seasonal variations in distribution, abundance and demography of Antarctic krill (Euphausia superba) and salps (Salpa thompsoni), and distribution and abundance of biomass dominant copepod species and other common zooplankton taxa. Comparisons were also made with data obtained during 1992-2000 AMLR field seasons to assess interannual variations. Mean and median krill abundance values in the Elephant Island area during the 2000/2001 field season were intermediate to highs in 1996 and lows in 1999. Increased abundance relative to 1999 resulted in part from recruitment of the 1998/99 and 1999/2000 year classes as indicated by modest proportions of juvenile and immature stages. Large proportions of advanced female maturity stages, substantial larval krill concentrations and more developed larval stages during February-March reflected normal seasonal spawning in 2000/2001. This is the third year in a row that spawning conditions have been favorable for krill recruitment success. Both large area surveys were characterized by wide spread distribution of abundant salps but extremely large concentrations like those of the 1993 and 1998 salp years were not encountered. Length frequency distribution of the dominant aggregate stage indicated a curtailed production season. A dramatic 60% abundance decrease between the two surveys was apparently due to loss of large aggregates from the upper water column. Within the 1993-2001 Elephant Island data set prolonged salp budding periods with pulses of late-season aggregate production preceded years with enhanced salp population size while curtailed budding periods preceded years with diminished salp populations. Assuming that these trends continue, reduced salp population size can be expected during the 2002 field season. Favorable krill spawning conditions in conjunction with reduced salp abundance improve the prospects of larval production and survival. Should winter sea ice development and spring bloom conditions also be favorable we may expect strong recruitment success of the 2000/2001 year class. Copepod abundance values in the Elephant Island area were among the highest observed over the past 20 years. This resulted from large concentrations of Calanoides acutus, Metridia gerlachei and Calanus propinquus and indicate enrichment in oceanic and coastal waters relative to other years.

There is a wealth of earlier papers on the topic of krill processing dominated by the works of Grantham (1977) “The Utilization of Krill”, Budzinski et al (1985), “The Possibilities of Processing and Marketing of Products Made from Antarctic Krill”, and from works produced by J. K McElroy (1980-82). Within these papers are the fundamentals of product yields and the framework for determining market prices for Krill Products.
Yield Estimates from round (Whole) Krill are as follows from McElroy (1980-82):
Whole Uncooked Krill- Frozen 100%
Whole Cooked Krill-Frozen 90%
Whole Uncooked Krill Centrifuged (Gutted) Frozen 80%
Krill Mince-centrifuged 60%
Krill Mince-Uncentrifuged 80%
Krill Tail Meat 15%
Krill Meal without Stickwater Recovery 15%
Krill Meal with Stickwater Recovery 21%.
In summary, krill production has some time of uncertainty ahead due to a shake out of the industry, with departure of older vessels and technology and uncertain markets for the mid term future for higher value human products.

The long-term objective of the U.S. AMLR field research program is to describe the functional relationships between Antarctic krill, their predators, and key environmental variables. Every year on-land studies of predator foraging ecology and reproductive success have been coordinated with large scale oceanographic surveys off the South Shetland Islands. Since 1996/97, U.S.-AMLR predator studies have taken place at Cape Shirreff, Livingston Island. This report summarizes the pinniped portion of predator studies for the 2000/01 austral summer.