Makarov, R.R. (1990), Size compositions of males and females in the course of the life cycle of Euphausia superba

Earlier studies did not pay attention to differences in size composition of Euphausia superba populations by sex and its seasonal variability. In this paper variations in size and sex composition of samples from commercial catches are analyzed over the reproductive season, using samples from different years. The observed variations were related to stages of krill maturity during the reproductive cycle. Information on size composition by sex is considered to be vital for an understanding of krill population structure. It is suggested that duties of biologist-observers aboard commercial vessels should include not only measurement but also sex determination of adult krill.

Ichii, T. (1990), Homogeneity of body length composition of Antarctic krill within the commercial zone

The homogeneity of krill (Euphausia superba) length composition in commercial trawl catches (hauls) was investigated by comparing length compositions from different parts of the same haul. There was no significant difference (P>0.5) in 53 out of 60 hauls. Therefore it is concluded that sampling from one part of the haul provides a reasonable estimate of length composition in the entire haul. In contrast to small variations in length composition within the same haul, variation between different hauls was most noticeable in areas where krill length frequency compositions were bimodal.

Miller, D.G.M. (1990), On the intensity of sampling krill trawl catches

This paper uses actual krill length-frequency data in an attempt to address the problem of the determination of adequate sample size to obtain representative krill length-frequency distributions from commercial catches. The possible effect of two other factors (within-trawl variability and sample decomposition) which may influence length-frequency data quality is also considered. Attention is drawn to the following:

• all measurements of length from commercial krill; catches should be made, as far as possible, by a single observer/vessel;

• consideration still has to be given to the minimum length differences which should be detectable between catches. Account must be also taken of the desired biological characteristics which are to be discerned (e.g., length-with-age). At present, and in the interests of both statistical rigour and efficiency of measurement, it is proposed that length measurements made on commercial krill catches should be grouped into 2 mm size classes;

• biological implications associated with the detection of specific differences in length should be considered in conjunction with the need to collect information on maturity stages;

• for most purposes a minimum sample size of at least 100 animals/trawl is necessary to obtain statistically meaningful differences between samples; and

• the problem of how frequently commercial krill catches should be sampled still requires consideration.

Kasatkina, S.M. and V.I. Latogursky (1990), Distribution characteristics of krill aggregations in the fishing ground off Coronation Island in the 1989/90 season

Distributional characteristics of krill aggregations in the Coronation Island fishing ground were examined in relation to environmental factors, the biological condition of krill and the performance of the fishery. Investigations were carried out from October 1989 to February 1990. An echo sounder was used to assess the characteristics of krill aggregations. Krill was harvested by standard midwater trawls with a horizontal mouth opening of 33 m. All common types of krill aggregations were recorded in the Coronation Island area over the observation period. From November to February scattered forms of krill tended to combine into larger aggregations. Wind force had no direct or indirect influence on the types of krill aggregations or their density. The increased temperature towards the end of the season, however, assisted the development of phytoplankton which in turn led to an increase in krill concentration. The biological parameters of krill examined (stages of maturity, sex ratio and krill size) varied according to aggregation type. The results obtained should be regarded as preliminary since they were based on data from one season only. Distributional characteristics of krill aggregations varied significantly over time. It was therefore recommended that CPUE simulation studies take into account the actual distributional features of targeted aggregations and the catchability rates of the trawls used at different times in the life of the fishery.

Hampton, I. (1990), Measurements of differences in the target strength of Antarctic krill (Euphausia superba) swarms at 38 kHz and 120 kHz

Differences in the target strength of adult (36 to 60 mm) Antarctic krill (Euphausia superba) at 38 and 120 kHz have been inferred from differences in the mean back-scattering strength of swarms simultaneously insonified at these two frequencies in studies off the South Orkneys and Elephant Island in March 1990. Back-scattering strengths at 120 kHz ran consistently about 7 dB higher than at 38 kHz, a difference which was regarded as too large to be explained by possible experimental error, and which was therefore attributed to real differences in average target strength at these two frequencies. The results are in good agreement with recent experimental work on the target strength of encaged E. superba at 38 and 120 kHz but are in major conflict with the 120 kHz - to - 50 kHz target strength conversion factor used at the Post-FIBEX Acoustic Workshop in 1984.

Zimarev, Yu.V., S.M. Kasatkina and Yu.P. Frolov (1990), Midwater trawl catchability in relation to krill and possible ways of assessing gross catch

Research into midwater trawl catchability rates was carried out on the basis of data obtained from AtlantNIRO expeditions from 1983 to 1990 in the Scotia Sea. A methodology was developed for and applied to determining the rate of krill filtration through the trawl rope and netting and also the probability that krill will come into contact with various parts of the net as it passes through the trawl sides. Studies were based on the results of 250 hauls made with a 72/308 trawl. Catchability was worked out with the aid of fine-meshed chafers, hydroacoustic methods and theoretical calculations. A comparison of the experimental hydroacoustic assessment with the calculated one demonstrated that the theoretical model agreed well with the real situation. Analysis of the efficiency of midwater trawls in the krill fishery indicates that the potential exists for this efficiency to be increased.

Fedotov, A.C. (1990), Krill biomass assessment in Statistical Area 48 from the RV AtlantNIRO data - Autumn 1989/90

A krill biomass census survey was carried out at two fishing grounds in the South Sandwich and South Orkney Islands areas during a cruise by RV AtlantNIRO in March/April 1990. The survey was conducted in the upper 100 m layer using a modified Isaacs-Kidd trawl. Trawling speed was 3.2 to 3.6 knots. The total krill stock on the poorly studied site off the South Sandwich Islands was assessed at 3.8 million tonnes, most of which was concentrated in the waters of the Weddell Sea. In contrast to this site, the one off the South Orkney Islands is well-established in terms of both research and commercial harvesting. The overall krill stock here was estimated to be 1.1 million tonnes. Most of this stock was concentrated in the south-western part of the Coronation Island shelf.

Latogursky, V.I., R.R. Makarov and L.G. Maklygin (1990), Distribution, biomass and characteristics of the Euphausia superba fishery around South Georgia (Subarea 48.3)

Krill distribution in the South Georgia area and many aspects of its variability have been extensively described in scientific literature. A summary of recent findings is discussed in this paper. There has been less focus on data concerning krill biomass assessments. The existing uncertainty in krill biomass assessment can be largely attributed to high variability and the wide range of biomass values obtained which in turn leads to uncertainty in interpreting krill biomass for the area. It was therefore only possible to begin to explain the reasons for the variability in the scale of krill swarms and to attempt to determine more reliable values of its biomass after a number of census surveys had been conducted. Results of the nine most representative surveys conducted by Soviet scientists in the area from 1974 to 1988 are summarized in this paper. The most important survey data and biomass assessments have been tabulated and illustrated by various survey maps. It was found that the distribution of krill swarms corresponds largely with areas where currents turn into eddies. Among these areas, aggregations of krill were observed most often to the east of the island and around 37°W. When the water circulation system is unfavourable, which means the absence of eddy formations, krill do not usually form aggregations and its density is low. When water dynamics are favourable for krill aggregations its biomass around South Georgia is approximately 400-800 thousand tonnes. Unfavourable conditions correspond to a biomass of an order of magnitude less. Short-term fluctuations of krill biomass in the South Georgia area are extremely significant. Biomass may differ by as much as eight times in a month. It also usually decreases in spring, regardless of the type of water circulation. Annual differences in krill biomass are undoubtedly associated with the volume of krill brought here by waters of the Scotia Sea Secondary Front. More extensive studies incorporating trawl and acoustic surveys of different temporal and spatial scales are recommended in order to make reliable assessments of krill biomass.

Dolzhenkov, V.N. and V.P.Timonin (1990), Krill (Euphausia superba Dana) resources and distribution in the Wilkes Land area in the seasons 1986 to 1989

Results of krill (Euphausia superba Dana) resource surveys carried out along the Wilkes Land coast from 1986 to 1989 are presented in the paper. The surveys mainly focused on the search for exploitable krill aggregations. Two research vessels were simultaneously involved in the survey with one vessel conducting commercial krill fishing. The whole survey area from the coast to approximately 64°S between 130° and 150°E was subdivided into three subareas taking into account an area to the north of the edge of the continental slope. Each subarea was described in terms of the number of krill aggregations, regularity of their observations, krill density and total krill biomass. It was found that the above parameters are closely related to variability in oceanographic conditions and extent of the ice cover. If ice conditions are favourable, the subarea between 143° and 150°E was considered as the most valuable for the krill fishery. Krill aggregations were most frequently and regularly observed in the subarea. The mean annual density of krill in the subarea was 1 475 tonnes per square mile. The total biomass of krill in the Wilkes Land area was assessed as being about 1x10⁶ tonnes.

Bibik, V.A. and V.N. Yakovlev (1990), The status of krill (Euphausia superba DANA) resources in CCAMLR Statistical Divisions 58.4.2 and 58.4.3 from 1988 to 1990. Results of acoustic surveys

Since 1977 the YugNIRO Research Institute (Kerch, USSR) has carried out biological and ecological monitoring of krill resources in the central part of the Indian Ocean sector of the Antarctic (CCAMLR Statistical Divisions 58.4.2 and 58.4.3). Results of surveys conducted from 1988 to 1990 are discussed in the paper. It was found that the increase in krill biomass observed in the area in 1990 is linked with the abundant 1986 and 1987 year-classes and with a diminished rate of emigration of krill of these year-classes from the area in 1989/1990.

de la Mare, W.K. (1990), Factors to consider in developing management measures for krill

A brief review of the objectives of the Convention for the Conservation of Antarctic Marine Living Resources is given along with an outline of steps for the evolution of management procedures for krill fisheries. Various possible elements of procedures such as reactive, predictive, and feedback management, modelling, indicator species, pulse fishing, and the use of open and closed areas and seasons are outlined. Some interim management measures are suggested which could be implemented while a more generally applicable management is being developed.

Butterworth, D.S. (1990), Towards an initial operational management procedure for the krill fishery in Subareas 48.1, 48.2 and 48.3

An operational management procedure for krill (Euphausia superba) in Subareas 48.1, 48.2 and 48.3 requires a basis for the assessment of resource status, and an algorithm for specifying the levels of regulatory mechanisms (e.g., a catch control law) that depends on the results of the assessment. The development and selection of a procedure requires a basis for the simulation testing of procedures, and an operational definition of CCAMLR Article II to provide criteria against which to assess procedure performance. Suggestions are made under each of these headings. Assessment of resource status is provided by the CPUE ‘Composite Index’ proposed by the Workshop on the Krill CPUE Simulation Study. Annual TACs are restricted to an initial ceiling (C_c) for a five year period, with a reference CPUE level (CPUE_ref) calculated as the average CPUE over that time. Thereafter TACs may increase by C_r% per annum. However, this increase may be suspended or reversed in any year, depending on how many of the previous three years' CPUE values fall below a target level of 0.75 CPUE_ref. An operating model of krill dynamics in the region is developed for simulation testing purposes. A provisional operational interpretation of Article II is proposed: the primary objective is to prevent the expected lowest biomass of krill over a 20-year harvesting period from falling below 60% of its average unexploited level; subject to this constraint, accumulated catches should be as large as possible without substantial associated probability that TAC reductions may prove necessary during the 20-year period considered. Simulation tests, including one particular test of robustness to the assumptions of the operating model, are carried out to illustrate the overall process proposed; for this illustrative exercise, the choice of catch control law parameters would probably lie between (C_c=1 million tonnes; c_r=15%) and (C_c=2 million tonnes; c_r=10%). Suggestions for proceeding with further investigations of possible operational management procedures are made. It is proposed that possible alternative suggestions for such procedures should be made in a similar fashion to that set out in the paper. Suggestions by others for alternative forms and parameter values (or their probable ranges) for the krill dynamics operating model used for testing procedures are encouraged.

(Report of a Joint UK/USSR Workshop, 23 to 27 July 1990) (1990), Analysis of results from demersal fish surveys at South Georgia, undertaken by the United Kingdom and the USSR, January and February 1990

The report describes discussions and analyses of the data from a survey from MV Hill Cove in January 1990 and RV Akademik Knipovich in February 1990 around South Georgia. Both surveys were characterized by large numbers of small hauls interspersed with a few large catches. The small number of large catches cause a disproportionate increase in the estimated standing stock of Champsocephalus gunnari. The paper describes the ways in which these large hauls were considered in the analysis. No ideal method was found for incorporating the large hauls into the analysis.

Everson, I. and S. Campbell (1990), Toothfish, Dissostichus eleginoides, at South Georgia

The Dissostichus eleginoides fishery at South Georgia has expanded greatly in recent years. It has been claimed that the exploited fish are senescent and not contributing to the breeding population (CCAMLR-VIII, paragraph 106). Histological examination of the gonads of a small sample of fish taken from a commercial longliner in January 1990 indicates that the fish are sexually mature and, at the time of sampling, are approaching spawning condition.

Barrera-Oro, E. and E. Marschoff (1990), A declining trend in the abundance of Notothenia rossii marmorata and Notothenia gibberifrons observed in fjords in two sites in the South Shetland Islands

A declining trend observed in the abundance of Notothenia rossii marmorata and Notothenia gibberifrons in fjords in two sites in the South Shetland Islands (Subarea 48.1), is analyzed by a nested ANOVA and demonstrated as significant. The material for the current study was obtained with trammel nets at Potter Cove, King George/25 de Mayo I., over a period of eight years from 1983 to 1990 and in waters around Half-Moon I., Moon Bay, in 1989. The analysis was based on the proportion of catches of the abovementioned species in relation to Notothenia neglecta, a species with similar ecological habits in the fjords. Since sampling by this method did not utilize a consistent amount of effort between years, the analysis made use of standardized catch data by expressing the catches of N. rossii and N. gibberifrons in proportion to the catches of N. neglecta. A similar declining trend had been reported in the 1960s and 1970s for neighbouring sites in the South Shetland Islands. This phenomenon might be explained as a consequence of the depletion of the stocks due to commercial exploitation in the area in the early 1980s.

Everson, I. and C. Mitchell (1990), The fishery for Patagonotothen brevicauda guntheri in CCAMLR Subarea 48.3

Fine-scale data supplied to CCAMLR for 1987/88 showed that the catches of Patagonotothen brevicauda guntheri were five times greater in the South Georgia area than at Shag Rocks. Previous survey data and reports to the CCAMLR Working Group on Fish Stock Assessment indicated that this species was only ever caught at Shag Rocks. Therefore the South Georgia catches were almost certainly of another species. The small size of P.b. guntheri means that they can only be caught with net meshes so small that they would also catch undersized individuals of other, larger species. Survey results suggest that such fishing is likely to have a significant effect on other species. P.b. guntheri has been reported as a by-catch of other fisheries; this suggests that illegal nets were used.

Kochkin, P.N. (1990), Age determination of Champsocephalus gunnari Lönnberg, 1905 (Channichthyidae) taken in the South Georgia area in 1990

In January/February 1990 the UK and the USSR conducted two research cruises using the vessels RV Hill Cove and RV Akademik Knipovich to study the status of the Champsocephalus gunnari stock in the South Georgia area. In February 1990 the size composition of catches taken by Akademik Knipovich had three peaks corresponding to size groups of 16-18, 24-26 and 30-34 cm. Only vertebra samples (n=140) were used in age determination. Age groups from 1+ to 9+ were present in catches. Two peaks in size composition correspond with fish of the 1987 and 1985/86 year classes. The first small peak corresponds with the strong 1988 year class.

Bidenko, V.G. and I.G. Istomin (1990), Trawl bag selectivity in the Champsocephalus gunnari fishery

Experiments on trawl bag selectivity during fishing on pre-spawning concentrations of Champsocephalus gunnari were carried out in June 1990 in the South Georgia area concurrently with trawl surveys as part of the main biological and oceanic research program. The results presented here are based on 29 hauls and, due to the limited time available for experiments, should be considered as preliminary. L_50% was 24.8 cm and the selectivity factor was 3.10 for a mesh size of 80 mm. Comparison of these results with results from previous years demonstrates close similarity. A significant increase in modal length (up to 34-35 cm) as well as earlier sexual maturation of fish were noted. It was suggested that the use of Polish type chafers and a reinforced outer cover on trawl bags reduces the stress on the mesh threads and increases mesh openings therefore enhancing their selectivity properties. Further experiments are recommended in order to fully understand the mechanism involved.

Frolkina, G.A. and R.S. Dorovskikh (1990), On the instantaneous natural mortality rate of Champsocephalus gunnari, South Georgia (Subarea 48.3)

The instantaneous rate of natural mortality (M) of Champsocephalus gunnari in the South Georgia area was assessed using six different methods. Data on size composition of catches from 1964/65 to 1968/69 and the age/length key for the first half of 1972 were used in the calculations. The results provided a wide range of estimates for M. The discussion of the results suggested that M=0.56 should be used in stock assessment for C. gunnari in Subarea 48.3.

Gasiukov, P.S. (1990), Standardization of fishing effort for Champsocephalus gunnari in the South Georgia area (Subarea 48.3)

Traditional calculation of catch-per-unit-effort series is inflexible in its use of data types and has no estimate of accuracy. A standardized CPUE index for Champsocephalus gunnari fishing in Subarea 48.3 is derived using a multiplicative model and data from many different classes (countries, types of vessel, fishing gear, months and years). Multiple regression is used to solve the model and the resultant yearly standardized CPUE shows the same trends independent of the values selected to standardize the model. The mean coefficient of variation for the CPUE values was 0.399.

Kozlov, A.N., K.V. Shust and A.V. Zemsky (1990), Seasonal and inter-annual variability in the distribution of Electrona carlsbergi in the southern Polar Front area (the area to the north of South Georgia is used as an example)

From 1987 to 1989 VNIRO (USSR) conducted six trawl and acoustic surveys in the area to the north of South Georgia Is between 49° to 54°S and 25° to 40°W. The area is within the Polar Frontal Zone where mesopelagic fish from the family Myctophidae are found most frequently and regularly. Seasonal and inter-annual variability in distribution, density and biomass of the most abundant species of myctophids, Electrona carlsbergi, are analyzed and summarized in this paper. The species is also known to form large concentrations throughout the year. Results of surveys showed that the distribution and behaviour of E. carlsbergi are strongly related to environmental conditions in the area as well as to the availability and distribution of zooplankton. E. carlsbergi was found over the entire study area. The largest concentrations of the species, however, were found mainly along edges of the frontal zone where such fundamental environmental characteristics of water masses as currency dynamics, temperature and density, attain the highest level of variation. The most large-scale and dense concentrations of E. carlsbergi were observed in summer (December to February) when fish were distributed in the upper 50-100 m layer. The smallest and less dense concentrations were observed in the winter (June) at 200 m and deeper. The spring and autumn months were noted as transitional for parameters of vertical distribution and density of fish concentrations. Calculations of biomass of E. carlsbergi in the area indicated that its variability during the year is related to parameters of spatial and vertical distribution of fish. Interannual variability of E. carlsbergi biomass in the area was also observed.

Zemsky, A.V. and S.A. Zozulya (1990), A functional division of Electrona carlsbergi (Tåning, 1932) area of habitat in relation to the latitudinal zonation of the Southern Ocean

During the cruise of the RV Vozrozhdenie (VNIRO, USSR) in March/April 1990 an integrated study survey was conducted in the Southern Atlantic along two meridional transects at 17° and 20°W in the latitudes from 37°30' to 55°30'S. The survey was mainly focussed on studies of distribution of adult and pre-spawning Electrona carlsbergi and also on searching for possible spawning areas of the species. During the survey the following zones within the study area were identified as having different vertical structures of water masses: Subtropical Zone, Subtropical Frontal Zone, Sub-Antarctic Zone, Polar Frontal Zone and Antarctic Zone. Samples of E. carlsbergi were analysed by length composition, sex ratio and maturity stages in relation to the location where samples had been taken. The following division of the E. carlsbergi area of habitat was suggested after the analysis: feeding area - Polar Frontal Zone; reproduction area - Sub-Antarctic Zone and Subtropical Frontal Zone. The centre of the species' area of habitat is in the Sub-Antarctic Zone because the greatest range of fish length and stages of gonad maturity has been observed in this zone.

Mazhirina, G.P. (1990), On reproduction of Electrona carlsbergi (Tåning)

This paper presents results from histological examinations of gonads of Electrona carlsbergi from the Atlantic sector of the Southern Ocean. From materials available it has been ascertained that E. carlsbergi spawns in the notal waters. Maturation of females begins when body length reaches 76 to 78 mm. Vitellogenesis is synchronous. Vitelline eggs have a diameter from 150 to 650 μm; in hydrated oocytes it is up to 900 μm. Maturation of ovaries is continuous, and spawning is serial. The spawning season is long and coincides with summer/autumn in the Southern Hemisphere.

Gerasimova, O.V. (1990), Feeding and food intake of Electrona carlsbergi (Tåning, 1932) Myctophidae

In summer and autumn Electrona carlsbergi feeds mainly on copepods. Daily food intake estimated by various methods was from 3.7 to 5.6% of fish body weight. The amount of food consumed by E. carlsbergi during the year in the waters to the south of the Antarctic Convergence is about 15 times fish body weight.

Filin, A.A., K.V. Gorchinsky and V.M. Kiseleva (1990), Biomass of myctophids in the Atlantic sector of the Southern Ocean as estimated by acoustic surveys

Acoustic surveys carried out in the summer and autumn of 1987-1989 estimated the biomass of myctophids in the Atlantic sector of the Southern Ocean between 48° and 56° and from 8° to 48°W to be approximately 1.7x10⁶ tonnes. Over the greater part of the surveyed area the fish were sparsely distributed. Dense concentrations consisting predominantly of one myctophid species, Electrona carlsbergi, were found only in some limited areas. The bulk of the surveyed biomass of myctophids was found to be within the Antarctic Convergence area.

Sabourenkov, E.N. (1990), Mesopelagic fish of the Southern Ocean - summary results of recent Soviet studies

Since 1963, Soviet research on Antarctic mesopelagic fish has been carried out as a part of the general multi-disciplinary program of research on Antarctic biological resources. Studies concentrate primarily on the following four most abundant species: Electrona carlsbergi, Electrona antarctica, Krefftichthys (Protomyctophum) anderssoni and Gymnoscopelus nicholsi. The data obtained so far are sufficient to allow a description of the general ecology and distribution of these species. Some data are available on their feeding, reproduction and age/length composition. The paper summarizes recently published results of these studies. A general description of mesopelagic myctophids is followed by more detailed information on individual species. Some details of the biological characteristics of these species are summarized in tables with details on area, season and source of data. Some data, e.g. length composition of samples, are also illustrated in figures. The importance of studies on the role of myctophids in the Antarctic ecosystem is highlighted.

Everson, I. and S. Campbell (1990), Areas of seabed within selected depth ranges in CCAMLR Subarea 48.3, South Georgia

Areas of seabed within 50 m depth contours down to 250 m, between 250 and 500 m and deeper than 500 m have been estimated from nautical charts. The results are presented by CCAMLR fine-scale reporting areas.

de la Mare, W.K. and A. Constable (1990), Refinements to the strategy for managing depleted fish stocks based on CCAMLR objectives

A method of calculating fishing mortalities which will allow depleted fish stocks to recover to levels near those giving greatest net annual increment within two to three decades is illustrated. These fishing mortalities are based on probabilistic descriptions of the future states of a depleted stock, and take into account uncertainty in assessments. Sample calculations show that applying a policy of F_0.1 will not always lead to stock recovery in two to three decades, and hence that additional management policies are required for depleted stocks. The implications of these studies for defining the terms 'depleted' and 'target levels for recovery' are briefly discussed.

Rodhouse, P.G. (1990), A preliminary assessment of the stock of the ommastrephid squid Martialia hyadesi in the Scotia Sea based on data from predators

Cephalopod fisheries world-wide mainly target species from two families, Loliginidae and Ommastrephidae. Fisheries for the latter have been characterized by dramatically fluctuating annual catches and frequent switches to exploit new target species. It is likely, therefore, that exploitation of the sub-Antarctic ommastrephid species Martialia hyadesi; will be attempted in the future. This squid is an important component of the diet of several species of albatross and the southern elephant seal and is probably taken in significant quantities by several other Southern Ocean vertebrate predators. Estimated annual consumption by known predators in the Scotia Sea is 326 098 to 330 642 tonnes, 94% of which is taken by southern elephant seals, and the other species may take at least a further 51 400 tonnes. M. hyadesi probably has a life span of two years and a circumpolar distribution, but its biology and ecology are still virtually unknown. Given the commercial potential of the Southern Ocean stock of M. hyadesi and its significant role in the diet of some vertebrate predators, the species is clearly important within the context of the aims of CCAMLR and should attract greater research effort in the future.

Croxall, J.P. and T.D. Williams (1990), The gentoo penguin as a candidate species for the CCAMLR Ecosystem Monitoring Program

Based on dietary and other biological information collected over several years at Bird Island, South Georgia and at the South Shetland Islands (both within Integrated Study Regions (ISRs) of the CCAMLR Ecosystem Monitoring Program), we suggest (and provide a full bibliography of supporting literature) that the gentoo penguin meets the specified criteria qualifying species for inclusion in the CEMP. The extensive dependence of this species in these ISRs on Euphausia superba, (including in winter), its residence in the ISRs in winter and its early attainment of sexual maturity are all features of special relevance to the CEMP.

Croxall, J.P., C. Ricketts and A.G. Wood (1990), Food consumption by predators in a CCAMLR integrated study region

A detailed description of the structure and mode of operation of a model for estimating food consumption of seabird predators is provided. This model is a development of earlier ones used in the South Georgia Integrated Study Region and incorporates new features, allowing for seasonal variation in predator weight (and hence energy requirements), diet composition and prey energy content. Specimen outputs are provided, illustrating the changes produced by using these new sub-models. Results of initial sensitivity analyses indicate particular sensitivity to estimation of metabolic energy requirements. The system is directly applicable also to fur seals and could be modified to incorporate phocid seal data, when available. Prey categories are readily modifiable to sub-divide krill into sexes and maturity stages. With existing empirical data on breeding population size, diet, activity-specific energy requirements and foraging ranges, it is possible to make realistic estimates of krill consumption of penguins and fur seals during their breeding seasons within specified areas.

Vagin, A.V. and V.V. Popov (1990), Observation of seabirds in the Southern Ocean in 1988/89

This paper examines the numerical and species distribution of birds in the sub-Antarctic area of the Southern Ocean to the south of 60°S. Thirty minute observations were made daily during daylight hours at 8:00; 12:00, 16:00 and 20:00 ship-time, while sailing between Antarctic stations and while en route to ports of call. Maps summarize the distribution of 14 bird species as well as of the individual species: Antarctic, snow, and cape petrels and the southern fulmar. Ice distribution patterns prevailing over the study period are discussed as is the wide variability of numerical and species distribution in each oceanic sector of Antarctica.

Scolaro, J.A., Z.B. Stanganelli, H. Gallelli and D.F. Vergani (1990), Sexing of adult Adélie penguins by discriminant analysis of morphometric measurements

Discriminant analysis of eight morphometric measurements was used to determine the sex of Adélie penguins. A sample of 46 adult birds was taken for measurement from the breeding population at Stranger Point (King George/25 de Mayo Is., South Shetland Islands). The sex of each bird had been determined earlier by means of observing the birds' breeding behaviour (first incubation shift). It was found that the combination of flipper breadth, bill depth and length of the middle toe gave the most accurate sex discrimination (87% correct). Using measurements of flipper breadth and bill depth only also gave good results (80% correct).

Marschoff, E. and B. Gonzalez (1990), Optimization of survey sampling design in the detection of interannual variability and prey size selectivity in the diet of penguins

Based on the preliminary results of a survey of prey size in Adélie penguins, sampling designs intended for the detection of inter-annual variations in mean prey size and penguin size-related selectivity were analyzed in order to find the optimal allocation of observations at each level in nested ANOVA designs. The optimal numbers of penguins and krill to be used in the detection of inter-annual variability in the parameters concerned are recommended and a required sampling protocol is suggested.

A table of minimal numbers of penguins to be sampled as a function of number of sampling dates and magnitude of the variance component is given, under the assumptions of balanced design and the variance component of ‘penguin-by-date’ interaction equal to the variance component of ‘penguin-within-dates’ obtained from a previous study in Bahía Esperanza.

Restrictions have been fixed in accordance with the recommendations of the fourth meeting of WG-CEMP: minimum inter-annual variation for mean prey size is fixed at 10%; the test power is taken as 0.9 and Type I errors fixed at 0.1.

Cost values of manpower required are based on Argentinian logistics.

Agnew, D.J. (1990), Investigations of required sampling regimes for environmental parameters

The sensitivity of different sampling regimes in identifying inter-annual changes in environmental parameters was investigated using environmental data from Davis Station, Antarctica, from 1985 to 1987. Strong daily, depressional (4 to 5 days) and yearly cycles were seen in temperature, wind speed and pressure. Sampling daily maxima and minima would be sufficient to detect a 2 to 3°C change in monthly mean temperature over two years with a significance α of 0.05 and a power P of 0.8. Sampling wind speed continuously or as daily maxima and minima would be sufficient to detect a 10 to 20% change in monthly mean log-transformed wind speed α of 0.05 and P of 0.9.