Australia (1982–1984), An approach to a management strategy for the Antarctic marine ecosystem

A number of options for a management strategy ranging from total protection to harvesting at specific levels are discussed. These options are based on certain assumptions on the state of the system and consideration of past exploitation and present condition of stocks, Experimental fishing is suggested to obtain necessary information on responses within the ecosystem. Three areas of research priority are indicated and the design of experiments to assist management are proposed.

Butterworth, D.S. (1982–1984), Antarctic ecosystem management

This document describes a framework within which an initial strategy could be developed for managing commercial exploitation of the marine living resources of the Southern Ocean. More particularly, practical approaches are suggested for managing the exploitation of krill and fish in accordance with the objectives and requirements of Article II of the Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR). Quantitative predictions, and hence multi­species models, are necessary for assessing any indirect impact that might arise through the exploitation of either krill or fish, and they are necessary also if management is to be aimed at restoring depleted populations. The knowledge for these models is not available at present. Consequently, the report makes recommendations for (1) the type of research that is needed to improve the situation, and (2) interim management action that is regarded as practicable. The research includes (a) identifying those components (species) of the ecosystem that most significantly influence the dynamics of the system, (b) estimating their demographic status in subsystems, and (c) conducting perturbation experiments in certain of these subsystems. With regard to interim management action, it is recommended that (a) management areas should be delimited, (b) target levels for stock-size should be agreed and (c) both direct and indirect methods should be employed to monitor these stocks. In particular, early attempts should be made to model the fishing operation.

Bengtson, J.L. (1982–1984), Monitoring indicators of possible ecological changes in the Antarctic marine ecosystem

Fisheries assessment directed ecological studies and ecological monitoring are necessary to provide the information required for ecosystem management. Monitoring of indicator species to indirectly detect ecological trends in the Antarctic marine ecosystem is proposed. The most suitable indicator species for the Antarctic ecosystem are krill predators. Crabeater seals, Antarctic fur seals, chinstrap and Adelie penguins appear to have characteristics which offer the greatest potential as possible indicators of krill harvest-related changes in the ecosystem.

The paper briefly reviews the history and present status of Antarctic fisheries. To introduce the topic of the potential effects of harvest-related perturbations, some hypothetical impacts of past and future fisheries are presented. A section on the design of Antarctic monitoring programs discusses variation in the ecosystem, the detection of changes, the selection of indicator species, experimental design, and the application of various technologies to ecological monitoring.

Beddington, J.R. and W.K. de la Mare (1982–1984), Marine mammal fishery interactions: Modelling and the Southern Ocean

There are a number of possible ways that the interaction between krill and its marine mammal predators can be viewed. A decision to manage is in part based on the belief that marine mammals can affect the yield of fisheries and the fisheries, as their food supply can affect the dynamics of marine mammals. The problems of interpreting the precise scientific meaning of the management criteria of Article II of the CCAMLR Convention are discussed. The likely behaviour of different components of the ecosystem is considered in the light of the following simple theoretical models: krill-whales, krill-whales-seals, krill-cephalopods­ sperm whales. Practical difficulties of interpreting the current status of marine mammals from existing data are considered with special reference to possible competitive release resulting from the depletion of baleen whales. The different ways to acquire necessary information for management are mentioned including statistically designed perturbation experiments and monitoring of indicator species. Three classes of models can be used to assess mammal fisheries interactions. Theoretical models give guidance as to what sort of phenomena to look for, strategic simulation models indicate how to look for them and estimation models are the tools which summarise the observations for practical purposes. Such a process can be recursive. It is emphasised that modelling cannot substitute for experimentally rigorous observation and conversely, unguided observation provides only data, not insight.

Gulland, J. (1982–1984), Comments and questions on ecosystem management

The objectives of the Commission as set out in Article II of the Convention are briefly discussed and the two approaches to ecosystem analysis reviewed. The top-down approach, following the flow of energy from primary production through to the animals of interest give-s a broad understanding of how the system works, and rough estimates of the potential yield at various trophic levels. It is not very useful in formulating specific management advice e.g., whether a catch of the same order of magnitude as the potential yield is too high or not. For providing advice the bottom-up approach is more useful, starting with examining the dynamics of the stocks of individual species, especially those currently being exploited.

"Ecosystem management" in the Antarctic will therefore depend on having a good understanding of the dynamics of each important species. The present knowledge of the behaviour of different stocks under exploitation, and of the basic parameters (growth, mortality, etc.) is reviewed. These range from fairly good for whales, through moderate for fish and krill, to poor or non-existent for squid. The most serious inadequacy is probably the lack of good methods of monitoring changes in krill abundance. Most catch per unit data for krill reflect local density rather than overall abundance. 

The forms of interaction between species are discussed, and related to the work of modelling and data collection. It is suggested that of the various types of models, strategic simulation models which help address the right questions are, in the current state of knowledge, the most valuable.

Argentina (1982–1984), Conservation and management strategy for the Antarctic marine ecosystem

General consideration is given to the present status of the Antarctic ecosystem. Concern is expressed about the risks which might result from harvesting in a marine ecosystem still not correctly evaluated. Attention is drawn to the possible impact of such activities on adjacent and dependent ecosystems. Three possible goals for the rational management of the Antarctic marine living resources are considered taking into account practical possibilities of achievement; risk to the stability and diversity of the system; economic feasibility and benefits for humanity. The first two goals are the restoration of the ecosystem to pre­-exploitation level, and the conservation of the ecosystem at the present level. The third goal reflects the objectives of Article II of the CCAMLR Convention. This goal is considered the most appropriate. It is concluded that the current state of knowledge of the Antarctic Marine Ecosystem does not permit elaboration of a multispecies model. There is however sufficient information to allow use of a range of single-species models which may assist in predicting changes and laying down a basis for sound management. The single­ species models adapted for this purpose could then be used in the development of or as components of multi­species ecosystem models. Some immediate management actions are proposed.

Shimadzu, Y. (1982–1984), A review on the Antarctic ecosystem models

Some published articles on the Antarctic krill biomass estimates and ecosystem models by Japanese scientists were reviewed. The concept and treatment of Lotka-Volterra type model by Yamanaka (1983) and Nagata (1983) were compared and some future modifications were discussed. While a network model such as developed by Doi (1879) is able to deal with many components in the Antarctic eco­system simultaneously, it was felt a further review was needed to develop this model.

Sabourenkov, E. (1982–1984), Ecosystem monitoring and management - Summary of papers presented at the third meeting of the scientific committee

This paper is an attempt to summarise and identify agreement of points raised in a number of scientific papers on ecosystem management presented for the consideration of the Scientific Committee at its first three meetings. All points are collated according to the following major questions:

• Interpretation of the objectives of the Convention;
• General concept of Antarctic Ecosystem;
• Present state and existing trends in the ecosystem;
• Management approaches;
• Modelling;
• Indicator species monitoring;
• Plan of action.

Australia (1982–1984), Ecosystem management: Proposal for undertaking a coordinated fishing and research experiment at selected sites around Antarctica

This paper is presented to provide a basis for discussion of the experimental management approach. The experimental approach should enable management guidelines to be based on the best available scientific advice derived from experience and scientific research. Several criteria are suggested as a guide in selecting suitable sites for management experiments. An example experiment site, Prydz Bay, is discussed in detail. The proposed experiment in the Prydz Bay is in two phases, each of five years duration. During the first phase the level and type of fishing effort should be held constant while the ecology of the site is documented, population levels and trends of the target and key consumer species assessed and complementary research undertaken to further refine a conceptual and quantitative ecological model of the experimental site. In the second phase of the experiment the system could be manipulated through planned variation to the fishing pressure and, possibly, by the co-harvesting of selected consumer species. The effects of this manipulation would be studied to establish relationships between key members of the community and the results used to develop a plan of management for that sub-system.

U.S.A. (1982–1984), Detection of the possible indirect effects of harvesting and associated activities on the Antarctic marine ecosystem

The purpose of this paper is to indicate a number of possibilities and to facilitate development of an agreed plan for selecting, assessing and monitoring species, populations, and individual characteristics that will be likely sensitive indicators of possible indirect effects of harvesting and associated activities in the Convention Area. Harvesting is considered as a form of predation which can result in changes in stock status not only of target species but dependent and related species as well. There is a list of criteria to select appropriate indicators of harvest-related changes. Observation of by-catch during fishing operations and sightings of birds and mammals by observers aboard vessels engaged in fishing, research or other activities might be useful as a source of information for assessing possible indirect effects of harvesting and related activities in the Convention Area. It is suggested that penguins and pinnipeds have the greatest potential as possible indicators of krill availability. Some practical steps to identify possible indicator species and necessary research and monitoring programs are proposed.

Green-Hammond, K.A., D.G. Ainley, D.B. Siniff, and N. Scott Urguhart (1982–1984), Selection criteria and monitoring requirements for indirect indicators of changes in the availability of Antarctic krill applied to some pinniped and seabird information

Antarctic krill, Euphausia superba, is the dominant herbivore in the Antarctic marine food web and a principal component in the diets of: fin, blue, hump­back and minke whales; crabeater seals and Antarctic fur seals; Adelie, chinstrap, macaroni and rock-hopper penguins; several other species of seabirds; and several species of fishes and squid. Some of these species are eaten in turn by sperm whales, killer whales, leopard seals, and other higher order pre­dators. Thus, if it is not developed and managed properly, the fishery for E. superba could affect many dependent species and the basic structure and dynamics of the Antarctic marine food web, as well as the distribution, abundance or productivity of krill itself.

Bengtson, J.L. and R.M. Laws (1982–1984), Trends in crabeater seal age at maturity: An insight into Antarctic marine interactions

The crabeater seal, Lobodon carcinophaqus, is a species which appears to be useful as an indicator of marine. community interactions. Crabeater seals eat krill almost exclusively, live up to 40 years of age, have a circumpolar distribution and a large standing stock. The age at which crabeater seals reach sexual maturity is a parameter which might reflect changes in krill availability. Abundant food and relatively faster growth rates may lead to attaining sexual maturity earlier, decreased food availability would presumably have an opposite effect. The data on age at maturity previously published are reviewed in the light of recent material from the Antarctic Peninsula and an expanded sample. from Marguerite Bay. A correlation is demonstrated between Baleen whale catch data and seal maturity data from the study area. The age of sexual maturity in crabeater seals apparently decreased as a result of whaling and subsequently increased when whaling ceased. The causes of observed changes are likely to be related to complex interactions within the marine ecosystem. This study demonstrated the value of one aspect of crabeater seals as an indicator species. It is important that sampling of crabeater seals continue for monitoring studies of the Antarctic marine ecosystem.

Sissenwine, M.P. (1982–1984), Modelling: The application of a research tool to Antarctic marine living resources

Modelling is an integral part of fisheries research throughout the world. The significant advances resulting from modelling studies directed at the North Sea and Georges Bank (North-West Atlantic) are considered. The North Sea model is a multi-species extension of the Beverton and Holt yield per recruit model. The Georges Bank model describes a static energy budget of this area. Several models have already been applied to marine living resources of the Antarctic. The pelagic ecosystem of the Ross Sea has been simulated. Behaviour of biological systems exploited simultaneously at two or more trophic levels (e.g. baleen whales and krill) has been studied by means of heuristic models. Numerous modelling investigations have been related to assessment and management of whale stocks. Several examples of specific research and management problems for the Antarctic which may be treated by modelling are provided. Modelling should be an integral part of research on Antarctic marine living resources.

Lubimova, T. G., R.R. Makavov, V.V. Maslennikov, V.V. Shetsovand and K.V. Shust (1982–1984), The ecological peculiarities, stocks and role of E. superba in the trophic structure of the Antarctic ecosystem

Soviet data on the abundance and geographical distribution of krill in the Southern Ocean are analytically reviewed. The location of heavy krill concentrations around Antarctica is discussed on the basis of the peculiarities of its biology and environmental conditions. Krill consumption by the major groups of predators is assessed taking into account the results of Soviet investigations as well as data published in other countries. An allowable catch of 25-30 million tons of krill is suggested on the basis of direct sampling in areas of krill concentration. Such annual catch of krill is considered safe for the status of stocks of krill and dependent consumers.