Zaucha, J. (1987), Preliminary appraisal of Antarctic fish selection by the 32/36 bottom trawl combined with various codends

Selectivity properties of single and doubler-layer twine codends (mesh size 120 mm) and single-layer tape codends with a mesh size of 60 and 100 mm were determined. It was found that the selectivity properties of twine codends are unsatisfactory in the case of Antarctic icefish, bumphead notothenia, and Scotia Sea icefish. This was primarily caused by the heavy net material used for their construction, incorrectly chosen mesh size, and certain morphological features of some Antarctic fish, which make it difficult for them to escape from the codend. Selectivity properties of both tape codends were much better. It was found that an optimum mesh size of this codend for selection of Antarctic icefish and bumphead notothenia ranges from 60 to 100 mm. For other Antarctic fish, especially Scotia Sea icefish and South Georgia icefish the determination of a proper mesh size of trawls used in fishing for them requires further research. It should first of all cover twine codends with a mesh size of 80 mm, currently used on factory trawlers, as well as codends with a structure resembling tape codends.

Everson, I. (1987), Areas of seabed within selected depth ranges in the South-West Atlantic and Antarctic Peninsula regions of the Southern Ocean

Data were tabulated for FAO sub-areas: 48.1 (East), 48.1 (West), 48.2, 48.3, 48.4, 48.5 and 88. Total areas and sea areas were given for these categories. Areas estimated from admiralty charts were expressed as percentages for the following depth ranges: 0-50, 50-100, 150-250, 250-500 and >500m; 0-150, 0-250, 0-500, >50, >150, and >500m. Extra detailed information was presented for subdivisions 50, 51, and 52 of sub-area 48.3.

Gherasimchook, V.V., V.N. Brodin, A.V. Kljausov, I.B. Russelo, P.V. Tishkov and N.B. Zaremba (1987), Brief report of the joint Soviet-Australian expedition of the USSR FRV Professor Mesyatsev to the Australian fishing zone around the territory of Heard and McDonald Islands, May-August, 1987

The results of the first joint Soviet-Australian expedition to the AFZ around Heard and McDonald Islands are briefly reported. Environmental conditions of the shelf area of Heard were favourable for the formation of commercial aggregations of Champsocephalus gunnari during the austral winter. Stability of the aggregation is discussed in relation to the environmental conditions. The unique character of Heard’s population of C. gunnari was determined according to a number of biological and morphological parameters. A preliminary stock assessment of the detected aggregation of C. gunnari is given.

North, A.W. (1987), Distribution of fish larvae at South Georgia: horizontal, vertical, and temporal distribution and early life history relevant to monitoring year-class strength and recruitment

Four studies on the early life history stages of Antarctic fish at South Georgia are reported. In winter and summer fish larvae and early juveniles were present over the continental shelf and abundant near the coast, but rare in oceanic waters. During winter in the 265 m deep fiord of Cumberland East Bay the early stages of many species were found throughout the water column. In summer only four species of larvae were abundant, they were found in the upper 100 m of the water column, especially the top 2 m layer at certain times of day. In both seasons some species showed daily vertical migration.

The findings are discussed in relation to surveys for sampling the early stages of fish at South Georgia, with special reference to the early life history of Champsocephalus gunnari.

Gabriel, W.L. (1987), Results of fish stock assessment survey, South Georgia region, November - December 1986

Biomasses and length compositions of eight stocks from South Georgia are described based on results of a stratified random bottom trawl survey. A total of 124 tows were undertaken between 29 November and 17 December 1986 by the R.V. Professor Siedlecki using a Polish B-454 otter trawl. Biomass was estimated based on stratified swept-area calculations. Estimates of biomass of Notothenia rossii and Patagonotothen brevicauda guntheri were an order of magnitude lower than observe by Kock in 1985. Abundance of Dissostichus eleginoides and Pseudochanichthys georgianus appeared lower in 1986/87 than 1984/85, although not by an order of magnitude. Abundances of Notothenia gibberifrons and Chaenocephalus aceratus as estimated by this study and Kock were roughly equal. Abundance estimates of Champsocephalus gunnari were larger in 1986/87 than 1984/85, probably due to good recruitment of 1983/84 and 1984/85 year classes. Coefficients of variation ranged from 67.9% (Notothenia squamifrons) to 12.6% (C. aceratus).

Mucha, M. and W. Ślósarczyk (1987), Analysis of changes in biomass of fish stocks in the South Georgia area in 1976/77-1986/87

The swept area method was used to estimate biomass density changes in the stocks of five fish species (Champsocephalus gunnari, Chaenocephalus aceratus, Pseudochaenichthys georgianus, Notothenia gibberifrons and Notothenia rossii marmorata) in the South Georgia area in the seasons 1976/77-1986/87. In most of the seasons analysed, the estimates covered a near-bottom layer in about 1/6 of the area of the island shelf. 

Assessment results point to considerable variations in fish biomass density, in the studied period. Estimates of fish stocks biomass ranged from 43 to 158 thousand tons. The changes in the biomass level are first of all a result of periodical fluctuations in the biomass density of C. gunnari stock. High biomass density appeared with 2-4 year intervals after recruiting an abundant year-class to the exploited stock. The biomass of other bottom species is more stable, especially in the case of N. gibberifrons. Recently, an increase in the C. aceratus stock has been observed and, at the same time, there has been a gradual decline in the P. georgianus stock.

Kizner, Z.I. (1987), The error of the biomass estimate as a function of survey parameters and the statistics of a density field of krill aggregations

Simple relationships expressing the dependence of relative sampling error in a biomass estimate (from a survey) on the statistical characteristics of the fish concentration density field and on parameters of the survey itself, have been derived with the help of mathematical statistics and methods of calculus of probabilities. The biomass estimate is determined as the product of the average density for the region under examination and the area of this region. For a hydroacoustic survey, the anisotropy parameters correlation radius along transects and coefficient of variation serve as field characteristics on which the error depends. The direction of the survey with respect to the axis of the correlation ellipse and the frequency of transects (sections) serve as survey parameters. The relationships described here can be used in practice for both a posteriori estimation of the error made when calculating the biomass, and for survey planning on the basis of a priori estimates of the statistical characteristics of the concentration density field. These might provide a basis for the operative control of surveys.

Hennemuth, R.C., K.D. Bisack and G. Duhamel (1987), Simulation of recovery rates of fish stocks in the South Georgia and Kerguelen Islands areas

The benefits of conservation measures are generally based on the rebuilding of the depleted stocks and improvement in yields. It is desirable that such measures be based on the expected rate of recovery relative to rates of fishing.

A simulation model based on a probabilistic recruitment function was developed to provide long-term projections of the magnitude and rate of recovery of important fish stocks. While annual recruitment is the primary factor affecting recovery, the age of first recruitment is also an important consideration.

The simulated yields correspond, on the average, with the past observations. The simulations may prove useful in comparing observed performance of regulations to the expected outcomes from the simulations.

Gulland, J.A. (1987), Beyond MSY: a consideration of definitions of management objectives

The concept of ‘Maximum Sustainable Yield’ (MSY) has provided a useful guideline for resource management under the assumptions of a simple population model and simple objectives. This paper explores different guidelines under more realistic population models, taking account of the objectives set out in Article II of the CCAMLR Convention. The criteria will depend on whether the main concern is with recruitment or growth overfishing. Account also needs to be taken of the uncertainties associated with any assessment. Suggestions are made for the provision of advice to the Commission for the finfish and krill fisheries.

Rodhouse, P.G. (1987), Cephalopod research in the Antarctic

Cephalopods are a major component of the Antarctic marine food web and it seems inevitable that they will be the subject of future commercial exploitation. Research is being carried out at BAS on the species composition and distribution of Antarctic cephalopods, their production and biomass, population dynamics and trophic relations. However, there is insufficient information at present for CCAMLR to formulate effective policy for management of Antarctic cephalopods. In view of the rapidity that cephalopod fisheries can develop there is need for co-ordinated international research effort. Any commercial fishing for cephalopods should be fully monitored, research should be concentrated on population biology and trophic relations of cephalopods and a central reference collection of Antarctic cephalopods should be established. The Cephalopod International Advisory Council (CIAC) should receive the support of CCAMLR.

Ichii, T. (1987), Observations of fishing operations on a krill trawler and distributional behaviour of krill off Wilkes Land during the 1985/86 season

Japanese krill fishing operations were observed on board a commercial vessel and the actual operation described in detail. ‘Fish-finder’ was most useful in detecting swarms, while sonar was used to judge the towing direction. The size of fished swarms ranged from 100 m to 10 km with different distributions occurring in different fishing areas. While catch per towing time reflects within-swarm density, catch per day was thought to be a good index to measure abundance of a concentration. Comparison of such an index across time and space may prove difficult due to problems of standardization when data from different vessels are to be used.

Siegel, V. (1987), Age and growth of Antarctic euphausiacea (crustacea) under natural conditions

Five species of Antarctic euphausiid crustaceans were studied from the Antarctic Peninsula and the south-eastern Weddell Sea. Life spans range from two years for Euphausia frigida to six years for the krill Euphausia superba. Growth in length and weight was calculated by non-linear regressions. No difference in growth of krill was observed between the Antarctic Peninsula area and the eastern Weddell Sea. Former opinions that differ are discussed. Seasonal growth was re-analyzed for the species Euphausia triacantha, and a three-year life span proposed. Male Euphausia crystallorophias have a shorter life span than females, while their growth rate is similar. A short description of the life cycle and generation time of each species is given. In general, Antarctic euphausiids seem to remature and spawn at least twice and in some cases three times during their life, except for E. frigida which spawns only once.

(Published in Marine Biology, 96: 483-495 (1987))

Morris D.J., J.L. Watkins, C. Ricketts, F. Buchholz, and J. Priddle (1987), An assessment of the merits of length and weight measurements of Antarctic krill Euphausia superba

Published relationships of various length measurements as predictors of wet or dry weight in Antarctic krill Euphausia superba Dana are standardised with new data on the relationships of three length measurements to wet and dry weight as functions of sex, maturity stage and moult stage. The range of coefficients and exponents for these relationships are examined and an example given to indicate the potential such variation has for introducing error into estimates of biomass based on acoustic data. An alternative approach is examined in which length and additional biological data are assessed in terms of decreases in the residual variance of relationships. We have identified key sources of variability where relatively small increases in the effort of analysis result in large improvements in the precision of prediction. Surprisingly, the stage of the moult cycle of the animal has little effect upon length-weight relationships. The use of categories of sex and maturity stage, however, has marked effect upon the residual variance. Again surprisingly, the simple division of krill into male and female categories is of little practical use in improving the precision of any prediction of mass. However, the separation of gravid females, either from male or non-gravid female krill or, from adult male and other krill does result in a marked improvement in the precision of prediction. Example equations are provided.

(In press: British Antarctic Survey Bulletin No. 79 (May 1988)).

Everson, I. (1987), Can we satisfactorily estimate variation in krill abundance?

Knowledge of abundance and rates of change of abundance are basic requirements for fisheries models. Catch per unit effort (CPUE) has traditionally been used in demersal fisheries assessments as an estimator of abundance. It is less satisfactory for pelagic fisheries. Evidence is given that CPUE estimated from data reported to the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) does not provide a realistic index of krill abundance.

Recognising that there is a large natural year to year variation in krill abundance it is important that this be quantified and separated from fishery induced variation. The timescale for such information is discussed in the light of the needs of fishery management.

(In press in: Sahrhage, D. (ed). Antarctic Ocean and Resources Variability.
Springer. Berlin, Heidelberg, New York, Tokyo).

Everson, I. (1987), Prey monitoring surveys: a discussion of the characteristics necessary in prey surveys

The CCAMLR Ecosystem Monitoring Programme requires information on prey distribution to relate to changes in predator demography. The paper discusses the constraints imposed on such surveys and outlines some possible designs.

Marschoff, E.R., J.G. Visbeek and L.R. Fontana (1987), The utilization of seabird censuses for krill monitoring

The possibility of using bird observations made at sea as a means of monitoring krill in the Antarctic Ocean is explored. No variation source directly linked with krill was identified by means of correspondence analysis. Contour plotting, profile analysis and tests for equality of covariance matrices proved capable of detecting changes in bird abundance and/or species composition, associated with three levels of krill abundance.

A vector close to multi-normality was obtained, thus suggesting that refinements of the technique will allow the discrimination of krill levels by means of bird counts thereby providing an efficient tool for statistical tests of significance. The most promising approach seems to be the application of discriminant analysis.

Further developments of the method are possible only with greater databases, calling for international cooperation on the subject.

Bengtson, J.L., L.M. Ferm, T.J. Härkönen, E.G. Schaner and B.S. Stewart (1987), Survey of Antarctic fur seals in the South Shetland Islands, Antarctica, during the 1986/87 austral summer

A survey of Antarctic fur seals in the South Shetland Islands, Antarctica, during the 1986/87 austral summer indicated that this species is continuing its population recovery and recolonization of rookery sites following 19th Century commercial exploitation. Twelve fur seal pupping sites were identified, some of which had not previously been reported. The largest pupping sites are at Telmo Island and Cape Shirreff, on the north coast of Livingston Island. Total fur seal pup production in the South Shetland Islands in 1986/87 is estimated to be approximately 4000 individuals. Notes on other pinniped species observed during the survey are presented. The optimal sites for combined fur seal and penguin monitoring activities, as part of the CCAMLR Ecosystem Monitoring Program, are recommended as Seal Island, Elephant Island; Stigant Point, King George Island; and Cape Shirreff/Telmo Island, Livingston Island.

Bengtson, J.L. (1987), Long-term trends in the foraging patterns of female Antarctic fur seals at South Georgia

The number of feeding trips to sea made by female Antarctic fur seals during lactation may reflect the relative availability of local prey resources. Experimental work utilizing tetracycline-marked teeth confirmed that the feeding trip/suckling cycles of females are reflected as starving/suckling layers in the teeth of their pups. A collection of unmarked Antarctic fur seal teeth from Bird Island, South Georgia, was analyzed to estimate: 1) birth year of individuals, and 2) the number of feeding trips made by an individual’'s mother during lactation.

This analysis showed that between 1962 and 1981 the mean number of feeding trips made by female fur seals varied markedly. From 1962 to 1979 there were several significant increasing and decreasing trends in the mean number of feeding trips, with 1979 being the year with the fewest trips made during the entire 20 year period.

(In press in: Sahrhage, D. (ed). Antarctic Ocean and Resources Variability.
Springer. Berlin, Heidelberg, New York, Tokyo).

Croxall, J.P., T.S. McCann, P.A. Prince and P. Rothery (1987), Reproductive performance of seabirds and seals at South Georgia and Signy Island, South Orkney Islands, 1976-1987: implications for Southern Ocean monitoring studies

Aspects of the reproductive performance over the last decade of black-browed, grey-headed and wandering albatrosses, gentoo and macaroni penguins and Antarctic fur seals, at Bird Island, South Georgia and for Adélie and chinstrap penguins at Signy Island, South Orkney Islands, are summarised and reviewed. Breeding success of the wandering albatross, which breeds in winter and eats fish and squid, has remained constant, while population size has declined gradually but significantly. The other species at South Georgia, which breed in summer and feed extensively on krill, have shown major fluctuations in some or all of breeding population size, breeding success, foraging trip duration and offspring growth rate. 1977-78 and 1983-84 were summers of particularly poor reproductive performance by almost all species; circumstantial evidence relating this to reduced availability of krill is discussed. The fluctuations in reproductive performance of the krill-eating, summer-breeding penguins at Signy Island are not synchronised with those at South Georgia; they correlate best (especially for chinstraps, which suffered badly in 1980-81 and 1982-83) with the date of ice break-out in late spring. Numerous parameters of albatross, penguin and fur seal biology are reviewed in terms of their sensitivity and suitability for detecting changes in the marine environment.

(In press in: Sahrhage, D. (ed). Antarctic Ocean and Resources Variability.
Springer. Berlin, Heidelberg, New York, Tokyo).

Shuford, W.D. and L.B. Spear (1987), Surveys of breeding penguins and other seabirds in the South Shetland Islands, Antarctica, January-February 1987*

Surveys conducted as part of the Antarctic Marine Living Resources Program in 1987 provided data on the number, size, and location of penguin and Antarctic blue-eyed shag colonies and the breeding status of other seabirds in the South Shetland Islands, Antarctica. We encountered several species at many more sites than previously reported, thus increasing the known breeding localities of sheathbills and skuas by threefold, chinstrap penguins by twofold, and Cape petrels and shags by 50%. Our minimum estimate of 1 620 000 breeding chinstrap penguins, the most abundant penguin in the study area, is about 2.5 times greater than the previous estimate. Although there appears to have been about 40% overall increase in the chinstrap population in the last 20-30 years, about three-fourths of the difference between our counts and previous ones is due to more complete coverage of available nesting habitat in 1987. For the same reason, at least in part, other species of breeding seabirds were also found to be more abundant than previously reported.

(* Published in: NOAA Technical Memorandum NMFS Antarctic Marine Living Resources Program (AMLR))

Vergani, D.F., M.N. Lewis and Z.B. Stanganelli (1987), Observations on haul-out patterns and trends in the breeding populations of southern elephant seal at Península Valdés (Patagonia) and Stranger Point (25 de Mayo - King George I.)

Southern elephant seal, Mirounga leonina, populations at Península Valdés (Patagonia) and 25 de Mayo-King George I. were studied during the breeding season from 1979 to 1987. Two main objectives were taken into consideration: haul-out pattern and the female population trend. In both places, the intrinsic population growth rate is positive. In 1982, at Stranger Point, a sharp decrease of the female component of the population was observed (r=-56.54%). The recovery of the population at Stranger Point, and the global increase at Península Valdés, indicate the good condition of these populations.

Bester, M.N. and D.G.M. Miller (1987), Southern elephant seals and CCAMLR

This paper describes research findings of primarily South African (including some French and Australian results) studies on the southern elephant seal (Mirounga leonina) in the Kerguelen province of the Southern Ocean. Sub-populations of this species have declined at Kerguelen, Marion, Prince Edward and Heard Islands. Population studies during the animals’ terrestrial phase have failed to explain this observed decline which has also been recently confirmed for the Macquarie Island stock. The availability of food, competition with rapidly growing fur seal populations and competition with fishing fleets have all been suggested as possible causes of the elephant seal’s decline in the region. Such explanations assume that a communal feeding ground, not yet identified, exists and that this exerts some common influence on the species’ population dynamics. As such, study of both the elephant seal’s spatial and temporal distribution during its pelagic phase is extremely important. Recent South African research in this field has been initiated and it is hoped that this will help to elucidate the reasons for the observed decline of M. leonina in the southern Indian Ocean.

Hill, R.D. (1987), Archival and satellite-linked data recorders

This paper provides an overview of currently-available data recorders for use in research on marine animals. These recorders are deployed on freely swimming animals and gather data on aspects of an animal’'s diving behaviour. The records can be recovered in one of two ways: the data recorder must either be recovered intact, or the data recorder must be capable of disseminating its data via a radio link, such as the ARGOS satellite system. Recorders can be further subdivided into raw-data and processed-data recorders. Raw-data recorders keep a complete record of the diving parameters of interest and thus produce extensive records, whereas processed-data recorders only report summary statistics which may be quite brief. Due to the limited data-handling capacity of the ARGOS satellite system, most satellite-linked recorders will necessarily report processed data.

Kuechle, V.B. (1987), Telemetry monitoring of ecological resources

Current status of telemetry and location monitoring are discussed. Limitations on weight, communication range and service life are indicated. A general description of attachment methods and their limitations is given. Three automatic tracking system options are described. Several data recording methods are available including paper recorders and data recording using microprocessors with semiconductor memory. Satellite monitoring using the Argos/Tiros system and satellite transmission of data are also covered.

Chittleborough, R.G. (1987), A rationale for conservation areas within Antarctic waters

The application of potential conservation measures listed in Article IX 2 of the Convention requires ‘the designation of regions and sub-regions based on the distribution of populations of Antarctic marine living resources’ (Article IX 2 (b)). In order to select meaningful boundaries for such areas, first priority has been given to surface circulation of southern waters and the distribution of krill. This has been supplemented by (limited) information on the distribution of major consumers including baleen whales, seals and penguins. A possible relationship between general flowline features of the Antarctic ice cap and ragional dynamics of the Southern Ocean ecosystem is also suggested.

From the evidence available, the following six potential conservation areas are proposed:

70°W - 15°W
15°W - 40°E
40°E - 90°E
90°E - 150°E
150°E - 160°W
160°W - 70°W

Examples are given of options available for management approaches within these major conservation areas.