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FIGURE 10.10 Illustration of the cooperative international scientific research timetable for the Biological Investigations of Marine Antarctic Systems and Stocks (BIOMASS) program, which was created by the Scientific Committee on Antarctic Research. Basic and applied information (Fig. IV) about the Antarctic marine ecosystem were collected and analyzed through a series of integrated activities: scientific planning, technical preparation, seagoing experiments, other seagoing activities, shore based studies, data analysis, synthesis, and advice, workshops, and symposia. The First BIOMASS Experiment (FIBEX) and the Second BIOMASS Experiment (SIBEX) are shown. Modified from El-Sayed (1977).

with each other'' and ''with their physical environment.'' Moreover, instead of being arbitrarily defined south of 60° south latitude (Table 5.2), the Antarctic marine ecosystem was constrained within ecological boundaries ''south of the Antarctic Convergence'' (Figs. 8.3 and 10.4).

In Article II (the ecological backbone of CCAMLR), conservation was defined in terms of ''rational use'' with the objective of maintaining the ''ecological relationships between harvested, dependent and related populations.'' In addition, decreases in the ''size of any harvested population to levels below which ensure their stable recruitment'' would be prevented. Even the ''risk of changes in the marine ecosystem which are not potentially reversible over two or three decades'' would be prevented. Moreover, CCAMLR created an explicit goal of restoring depleted populations.

The concept of dependence, which is central to the ecosystem approach of Article II in CCAMLR, was expanded in the 1991 Protocol on Environmental Protection to the Antarctic Treaty (Protocol) to include ''dependent and associated ecosystems.'' In the same sense that marine and terrestrial ecosystems are associated around Antarctica (as demonstrated by the fur seals), there also are associ ations with ecosystems beyond the Antarctic region as noted in Annex II for birds and mammals that are ''indigenous to the Antarctic Treaty area or occurring there seasonally through natural migrations.'' In contrast to traditional marine resource management regimes, which focus on single species, CCAMLR and the Protocol have created ''ecosystem approaches'' for the rational use of all Antarctic living resources.

The principal challenges for managing ecosystems are related to accurately assessing species' demographics and variability. For example, populations of krill in the Antarctic marine ecosystem (Fig. 9.2) have been estimated to have a circumpolar biomass that ranges from less than 100 million to more than 7 billion tons, with an annual production that may exceed 1.3 billion tons. Clearly, such discrepancies preclude accurate MSY estimates. Moreover, the carrying capacities of populations also vary over time with changes in the ecosystem, indicating that optimal sustainable yields include environmental as well as species interactions.

In fact, the actual yield in a particular year can be quite variable, depending on environmental impacts that are unrelated to the fishery and affect natural mortality, growth, and recruitment processes throughout ecosystems (Fig. 10.11). To achieve this ecosystem objective, the CCAMLR Ecosystem Monitoring Program (CEMP) was created in 1984 to distinguish harvesting and environmental impacts on ''critical components of the ecosystem'' (Box 10.2)—acquiring information across the continuum from basic to applied research (Fig. IV).

FIGURE 10.11 Relationships between natural and human-induced environmental impacts that, along with targeted harvesting, influence population variations. Resulting population demographics (densities, size frequencies, and biomasses) influence the dynamics of ''dependent and associated ecosystems" and their feedbacks. Relevant figures are identified.

FIGURE 10.11 Relationships between natural and human-induced environmental impacts that, along with targeted harvesting, influence population variations. Resulting population demographics (densities, size frequencies, and biomasses) influence the dynamics of ''dependent and associated ecosystems" and their feedbacks. Relevant figures are identified.

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